Implement kCTF strategy

This implementation is pretty scuffed, but its more exploratory than anything else.

.gitignore

@@ -1 +0,0 @@
-node_modules

README.md

@@ -14,6 +14,6 @@ This is the impost monorepo, containing the following packages:
 - `@impost/lib`: A library that can be used to generate, solve, and verify
   proofs.
 
-It also contains a `solver` package, which is the Zig PoW solver that
-`@impost/lib` is built on top of, an example of how to use the solver in
-example-app
+It also contains a `solver` package, which is the PoW solver written in Zig,
+`@impost/lib` is built on top of, an example of how to use the solver in a
+nuxt 3 project.

example-app/.example.env

@@ -1 +1 @@
-IMPOST_HMAC_SECRET=xxx # openssl rand -base64 32
+YAPTCHA_HMAC_SECRET=xxx # openssl rand -base64 32

example-app/README.md

@@ -1,10 +1,10 @@
-# IMPOST
+# YAPTCHA
 
 Yet Another Pow capTCHA.
 
 ## What is this
 
-IMPOST is a proof of work based challenge-response system that is designed to
+YAPTCHA is a proof of work based challenge-response system that is designed to
 ward off spam and abuse.
 
 <!-- TODO: -->

example-app/app/pages/index.vue

@@ -9,7 +9,14 @@ if (!challengeData) {
 }
 
 function solved(ev: CustomEvent) {
-    console.log("Impost Solved:", ev.detail.solution);
+    console.log("Solved:", ev.detail.solution);
+    // $fetch('/api/pow/challenge', {
+    //     method: 'POST',
+    //     body: JSON.stringify({
+    //         challenge: ev.detail.challenge,
+    //         solution: ev.detail.solution,
+    //     }),
+    // });
 }
 
 function formsubmit(ev: Event) {
@@ -19,9 +26,9 @@ function formsubmit(ev: Event) {
 
 <template>
     <div class="flex justify-center items-center h-screen w-screen ">
-        <form @submit="formsubmit" action="/"
+        <form @submit.prevent="formsubmit"
             class="p-5 rounded-2xl bg-dark-9 border-coolGray-600 border flex flex-col gap-2">
-            <impost-captcha name="impost" challengeUrl="/api/pow" auto="onsubmit"
+            <pow-captcha challengeUrl="/api/pow" auto="onsubmit"
                 :challengejson="JSON.stringify(challengeData!.challenge)" @impost:solved="solved" />
             <input class="bg-blue-7 text-white font-semibold px-4 py-2.5 border-0 rounded-md" type="submit"
                 value="Submit" />

example-app/app/pages/index.vue.old

@@ -0,0 +1,411 @@
+<script setup lang="ts">
+import { type WorkerRequest, type SolutionMessage, WorkerResponseType, WorkerMessageType, ChallengeStrategy, type Challenge } from '~/types/pow';
+import WASMSolverUrl from "~/utils/solver.wasm?url";
+import ChallengeWorker from '~/utils/worker?worker';
+
+let shared_atomics = new SharedArrayBuffer(12);
+
+let workers: Worker[] = [];
+let workers_initialized = false;
+if (import.meta.client) {
+    try {
+        // const num_workers = 1;
+        const num_workers = navigator.hardwareConcurrency;
+
+        for (let i = 0; i < num_workers; i++) {
+            workers.push(new ChallengeWorker());
+        }
+    } catch (error: any) {
+        console.error("Failed to create worker:", error);
+    }
+}
+
+let autoSolve: Ref<boolean> = ref(false);
+watch(autoSolve, async () => {
+    if (autoSolve.value) {
+        while (autoSolve.value) {
+            if (solving.value) {
+                await new Promise(resolve => setTimeout(resolve, 100));
+                continue;
+            }
+
+            await getChallenge();
+            await solveChallenge();
+            if (!autoSolve.value) {
+                break;
+            }
+
+            await new Promise(resolve => setTimeout(resolve, 100));
+        }
+    }
+});
+
+let total_solved: Ref<number> = ref(0);
+let total_solving_for: Ref<number> = ref(0);
+
+function pluralize(value: number, string: string) {
+    return value === 1 ? string : `${string}s`;
+}
+
+let challenge_loading: Ref<boolean> = ref(false);
+let challenge_loading_indicator: Ref<string> = ref('');
+let challenge: Ref<Challenge | null> = ref(null);
+
+let nonce: Ref<string | null> = ref(null);
+let solved: Ref<boolean> = ref(false);
+let solving_for: Ref<string> = ref('0');
+
+const number_formatter = new Intl.NumberFormat('en-US', {
+    notation: 'compact',
+    compactDisplay: 'short',
+    maximumFractionDigits: 2,
+});
+
+// the hashrate of all the runs
+let hashrate_array: Ref<Array<number>> = ref([]);
+let hashrate = computed(() => {
+    if (hashrate_array.value.length === 0) {
+        return 0;
+    }
+
+    return hashrate_array.value.reduce((a, b) => a + b, 0) / hashrate_array.value.length;
+});
+
+let solving = ref(false);
+let solveTime: Ref<number> = ref(0);
+
+let solveTimeout: Ref<any | null> = ref(null);
+
+let challenge_error: Ref<string | null> = ref(null);
+
+let difficulty: Ref<number> = ref(0);
+
+let { data } = await useFetch('/api/pow/difficulty');
+
+if (data.value) {
+    difficulty.value = data.value.difficulty;
+}
+
+const MESSAGE_TIMEOUT = 3000;
+
+async function getChallenge() {
+    challenge_error.value = null;
+    challenge_loading_indicator.value = '';
+    challenge.value = null;
+    nonce.value = null;
+    challenge_loading.value = true;
+
+    const spinners = ['⠋', '⠙', '⠹', '⠸', '⠼', '⠴', '⠦', '⠧', '⠇', '⠏'];
+    let spinner_index = 0;
+    const loading_interval = setInterval(() => {
+        challenge_loading_indicator.value = spinners[spinner_index]!;
+        spinner_index = (spinner_index + 1) % spinners.length;
+        console.log(spinners[spinner_index]);
+    }, 100);
+
+    try {
+        const new_challenge = await $fetch('/api/pow/challenge');
+        challenge.value = new_challenge.challenge;
+    } catch (error: any) {
+        console.error("Failed to get challenge:", error);
+        challenge_error.value = `Failed to get challenge: ${error.message}`;
+    } finally {
+        challenge_loading.value = false;
+        clearInterval(loading_interval);
+    }
+}
+
+async function initWorkers() {
+    if (workers_initialized) {
+        throw createError("Workers already initialized");
+    }
+
+    workers_initialized = true;
+
+    const module = await WebAssembly.compileStreaming(fetch(WASMSolverUrl));
+
+    const atomics_view = new Int32Array(shared_atomics);
+    Atomics.store(atomics_view, 0, 0);
+    Atomics.store(atomics_view, 1, 0);
+
+    console.debug(`Initializing ${workers.length} workers`);
+
+    let worker_promises: Promise<void>[] = [];
+    for (let i = 0; i < workers.length; i++) {
+        const worker = workers[i]!;
+
+        worker_promises.push(new Promise<void>((resolve, reject) => {
+            const message_handler = (event: MessageEvent<SolutionMessage>) => {
+                if (event.data.type === WorkerResponseType.Error) {
+                    console.error("Worker error:", event.data.error);
+                    reject(event.data.error);
+                }
+
+                if (event.data.type === WorkerResponseType.Ok) {
+                    resolve();
+                }
+
+                reject(new Error("Unexpected message from worker"));
+            };
+
+            const error_handler = (error: ErrorEvent) => {
+                console.error("Worker error:", error);
+                reject(error);
+            };
+
+            worker.addEventListener('message', message_handler);
+            worker.addEventListener('error', error_handler);
+
+            worker.postMessage({
+                type: WorkerMessageType.Init,
+                module: module,
+                sab: shared_atomics,
+            } as WorkerRequest);
+        }));
+    }
+
+    const timeoutMs = 10 * 1000;
+    const timeoutPromise = new Promise((_, reject) => {
+        setTimeout(() => {
+            reject(new Error(`Function timed out after ${timeoutMs}ms`));
+        }, timeoutMs);
+    });
+
+    await Promise.race([
+        Promise.all(worker_promises),
+        timeoutPromise,
+    ]);
+
+    console.log("All workers initialized");
+}
+
+async function getChallengeSolution(worker: Worker, request: { strategy: ChallengeStrategy.LeadingZeroes, target: string, difficulty: number } | { strategy: ChallengeStrategy.TargetNumber, target: string, salt: string }): Promise<SolutionMessage> {
+    return new Promise<SolutionMessage>((resolve, reject) => {
+        const message_handler = (event: MessageEvent<SolutionMessage>) => {
+            worker.removeEventListener('message', message_handler);
+            worker.removeEventListener('error', error_handler);
+
+            resolve(event.data);
+        };
+
+        const error_handler = (error: ErrorEvent) => {
+            worker.removeEventListener('error', error_handler);
+            worker.removeEventListener('message', message_handler);
+            console.error("Worker error:", error);
+
+            reject(error);
+        };
+
+        worker.addEventListener('message', message_handler);
+        worker.addEventListener('error', error_handler);
+
+        switch (request.strategy) {
+            case ChallengeStrategy.LeadingZeroes:
+                worker.postMessage({
+                    strategy: ChallengeStrategy.LeadingZeroes,
+                    target: request.target,
+                    difficulty: request.difficulty,
+                } as WorkerRequest);
+                break;
+            case ChallengeStrategy.TargetNumber:
+                worker.postMessage({
+                    strategy: ChallengeStrategy.TargetNumber,
+                    target: request.target,
+                    salt: request.salt,
+                } as WorkerRequest);
+                break;
+        }
+    });
+}
+
+async function solveChallenge() {
+    if (!challenge.value?.target) {
+        return;
+    }
+
+    if (!workers_initialized) {
+        try {
+            await initWorkers();
+        } catch (error: any) {
+            console.error("Failed to initialize workers:", error);
+            return;
+        }
+    }
+
+    const atomics_view = new Int32Array(shared_atomics);
+    Atomics.store(atomics_view, 0, 0);
+    Atomics.store(atomics_view, 1, -1);
+
+    solved.value = false;
+    challenge_error.value = null;
+    solving.value = true;
+    solveTime.value = 0;
+    solving_for.value = '0';
+
+    let startTime = performance.now();
+
+    let solving_for_interval = setInterval(() => {
+        solving_for.value = ((performance.now() - startTime) / 1000).toFixed(1);
+    }, 100);
+
+    function cleanup() {
+        clearTimeout(solveTimeout.value);
+        solveTimeout.value = setTimeout(() => {
+            solveTime.value = 0;
+        }, MESSAGE_TIMEOUT);
+
+        solved.value = false;
+        solving.value = false;
+        clearInterval(solving_for_interval);
+    }
+
+    try {
+
+        let request: { strategy: ChallengeStrategy.LeadingZeroes, target: string, difficulty: number } | { strategy: ChallengeStrategy.TargetNumber, target: string, salt: string };
+
+        switch (challenge.value.strategy) {
+            case ChallengeStrategy.LeadingZeroes:
+                request = {
+                    strategy: ChallengeStrategy.LeadingZeroes,
+                    target: challenge.value.target,
+                    difficulty: challenge.value.difficulty,
+                };
+                break;
+            case ChallengeStrategy.TargetNumber:
+                request = {
+                    strategy: ChallengeStrategy.TargetNumber,
+                    target: challenge.value.target,
+                    salt: challenge.value.salt,
+                };
+                break;
+        }
+
+        let worker_promises: Promise<SolutionMessage>[] = [];
+        for (let worker of workers) {
+            // dispatch to all workers, func is async so it will not block
+            worker_promises.push(getChallengeSolution(worker, request));
+        }
+
+        let solution = await Promise.race(worker_promises);
+
+        if (solution.type === WorkerResponseType.Error) {
+            throw createError(solution.error);
+        }
+
+        if (solution.type === WorkerResponseType.Ok) {
+            throw createError("spurious solution");
+        }
+
+        console.log(shared_atomics.slice(8, 12));
+
+        nonce.value = Atomics.load(atomics_view, 1).toString();
+
+        solveTime.value = Math.floor(performance.now() - startTime);
+        total_solved.value += 1;
+        total_solving_for.value += solveTime.value;
+        // since nonce is the number of iterations we have completed, we can divide that by how long it took in second
+        // to get H/s
+        hashrate_array.value.push(+Atomics.load(atomics_view, 1) / (solveTime.value / 1000));
+        clearTimeout(solveTimeout.value);
+
+        await $fetch('/api/pow/challenge', {
+            method: 'POST',
+            body: {
+                challenge: challenge.value.target,
+                nonce: nonce.value,
+            }
+        });
+
+        solved.value = true;
+
+        solveTimeout.value = setTimeout(() => {
+            solveTime.value = 0;
+            solved.value = false;
+        }, MESSAGE_TIMEOUT);
+
+        switch (challenge.value.strategy) {
+            case ChallengeStrategy.LeadingZeroes:
+                console.debug("Solved challenge with difficulty", challenge.value.difficulty, "in " + solveTime.value + "ms");
+                break;
+            case ChallengeStrategy.TargetNumber:
+                console.debug("Solved challenge with salt", challenge.value.salt, "in " + solveTime.value + "ms");
+                break;
+        }
+
+        solving.value = false;
+        clearInterval(solving_for_interval);
+    } catch (error: any) {
+        challenge_error.value = `Failed to solve challenge: ${error.message}`;
+        console.error(error);
+        cleanup();
+    }
+}
+
+async function setDifficulty(difficulty: number) {
+    const response = await $fetch('/api/pow/difficulty', {
+        method: 'PUT',
+        body: {
+            difficulty,
+        }
+    });
+
+    console.log(response);
+}
+
+</script>
+
+<template>
+    <div class="flex justify-between" v-if="hashrate_array.length !== 0">
+        <span>Your average Hashrate: {{ number_formatter.format(hashrate) }} H/s</span>
+        <span>You have solved {{ total_solved }} {{ pluralize(total_solved, "challenge") }} in
+            {{ number_formatter.format(total_solving_for / 1000) }}s</span>
+        <span>Your Hashrate on the last challenge: {{ number_formatter.format(hashrate_array.at(-1)!) }} H/s</span>
+    </div>
+    <p v-else>You have not solved any challenges yet</p>
+    <p>Challenge: <span v-if="challenge_loading">{{ challenge_loading_indicator }}</span>
+        <span v-else>{{ challenge }}</span>
+    </p>
+    <p>Nonce: {{ nonce }}</p>
+    <button @click="getChallenge()" :disabled="solving || challenge_loading">
+        Get Challenge
+    </button>
+    <button @click="solveChallenge()" :disabled="solving || challenge === null || nonce !== null">
+        <span v-if="!solving">Solve Challenge</span>
+        <span v-else>Solving challenge for {{ solving_for }}s...</span>
+    </button>
+    <div>
+        <div v-if="solveTime && !challenge_error" class="min-h-[1rem]">
+            <span v-if="solved">Challenge solved in {{ solveTime }}ms!</span>
+            <span v-else>Validating solution...</span>
+        </div>
+        <div v-else-if="challenge_error">{{ challenge_error }}</div>
+        <p v-else class="empty-p"><!-- Empty so there is no content shift when there is text or isnt --></p>
+    </div>
+
+    <div class="flex flex-row w-fit">
+        <label for="autoSolve">Auto solve</label>
+        <input class="w-min" type="checkbox" v-model="autoSolve" id="autoSolve"></input>
+    </div>
+
+    <div class="flex flex-col w-fit">
+        <label for="difficulty">Difficulty</label>
+        <input class="w-min" type="number" min="1" max="64" v-model="difficulty" @change="setDifficulty(difficulty)"
+            id="difficulty"></input>
+    </div>
+</template>
+
+<style scoped>
+button {
+    min-width: 140px;
+    padding: 0.25rem 0.375rem;
+}
+
+.empty-p {
+    margin: 0;
+
+    &::after {
+        content: "-";
+        visibility: hidden;
+    }
+}
+</style>

example-app/app/utils/worker-name.ts

@@ -0,0 +1,6 @@
+const adjectives = ['swift', 'silent', 'hidden', 'clever', 'brave', 'sharp', 'shadow', 'crimson', 'bright', 'quiet', 'loud', 'happy', 'dark', 'evil', 'good', 'intelligent', 'lovely', 'mysterious', 'peaceful', 'powerful', 'pure', 'quiet', 'shiny', 'sleepy', 'strong', 'sweet', 'tall', 'warm', 'gentle', 'kind', 'nice', 'polite', 'rough', 'rude', 'scary', 'shy', 'silly', 'smart', 'strange', 'tough', 'ugly', 'vivid', 'wicked', 'wise', 'young', 'sleepy'];
+const nouns = ['fox', 'river', 'stone', 'cipher', 'link', 'comet', 'falcon', 'signal', 'anchor', 'spark', 'stone', 'comet', 'rocket', 'snake', 'snail', 'shark', 'elephant', 'cat', 'dog', 'whale', 'orca', 'cactus', 'flower', 'frog', 'toad', 'apple', 'strawberry', 'raspberry', 'lemon', 'bot', 'gopher', 'dinosaur', 'racoon', 'penguin', 'chameleon', 'atom', 'particle', 'witch', 'wizard', 'warlock', 'deer']
+
+export function getWorkerName() {
+    return `${adjectives[Math.floor(Math.random() * adjectives.length)]}-${nouns[Math.floor(Math.random() * nouns.length)]}`;
+}

example-app/app/utils/worker.ts

@@ -0,0 +1,170 @@
+// This worker just sits on another thread and waits for message to solve
+// challenges so that we dont block the render thread
+
+import {
+    type WorkerRequest,
+    type SolutionMessage,
+    WorkerMessageType,
+    WorkerResponseType,
+    ChallengeStrategy,
+} from "~/types/pow";
+
+const worker_name = getWorkerName();
+let solver: SolverModule | null = null;
+
+let atomic_nonce: Int32Array | null = null;
+let atomic_solution: Int32Array | null = null;
+
+async function loadWasmSolver(module: WebAssembly.Module) {
+    if (atomic_nonce === null || atomic_solution === null) {
+        throw createError("Atomics not initialized");
+    }
+
+    console.debug(`[${worker_name}]: Loading WASM solver`);
+
+    solver = await WebAssembly.instantiate(module, {
+        env: {
+            __get_solution: () => Atomics.load(atomic_solution!, 0),
+            __set_solution: (value: number) => Atomics.store(atomic_solution!, 0, value),
+            __cmpxchg_solution: (expected: number, replacement: number) => Atomics.compareExchange(atomic_solution!, 0, expected, replacement),
+            __fetch_add_nonce: (value: number) => Atomics.add(atomic_nonce!, 0, value),
+            __log: (ptr: number, len: number) => {
+                const string_data = new Uint8Array(solver!.exports.memory.buffer, ptr, len);
+                console.log(`[${worker_name}]: ${new TextDecoder().decode(string_data)}`);
+            },
+        }
+    }) as unknown as SolverModule;
+    console.debug(`[${worker_name}]: WASM solver loaded`);
+}
+
+onmessage = async (event: MessageEvent<WorkerRequest>) => {
+    if (event.data.type === WorkerMessageType.Init) {
+        console.log(`[${worker_name}]: Initializing...`);
+
+        atomic_nonce = new Int32Array(event.data.sab, 0, 1);
+        atomic_solution = new Int32Array(event.data.sab, 4, 1);
+
+        try {
+            await loadWasmSolver(event.data.module);
+        } catch (error: any) {
+            console.error(`[${worker_name}]: Failed to load WASM solver:`, error);
+            postMessage({
+                type: WorkerResponseType.Error,
+                error: `Could not load WASM solver: ${error.message}`,
+            } as SolutionMessage);
+            return;
+        }
+
+        if (!solver) {
+            console.error(`[${worker_name}]: Failed to load WASM solver`);
+            postMessage({
+                type: WorkerResponseType.Error,
+                error: "Failed to load WASM solver",
+            } as SolutionMessage);
+            return;
+        }
+
+        postMessage({
+            type: WorkerResponseType.Ok,
+        } as SolutionMessage);
+        return;
+    }
+
+    if (!solver) {
+        postMessage({
+            type: WorkerResponseType.Error,
+            error: "WASM solver not loaded",
+        } as SolutionMessage);
+        return;
+    }
+
+    const { strategy } = event.data;
+
+    const encoder = new TextEncoder();
+
+    let solution: number;
+    let target: string = event.data.target;
+    let target_bytes, target_ptr;
+    let memory;
+    switch (strategy) {
+        case ChallengeStrategy.LeadingZeroes:
+            const { difficulty } = event.data;
+            console.debug(`[${worker_name}]: recieved ${strategy} challenge: ${target}, difficulty: ${difficulty}`);
+
+            target_bytes = encoder.encode(target);
+
+            target_ptr = solver.exports.malloc(target_bytes.length);
+            if (target_ptr === 0 || target_ptr === null) {
+                console.error(`[${worker_name}]: Failed to allocate memory for challenge string`);
+                postMessage({
+                    type: WorkerResponseType.Error,
+                    error: "Failed to allocate memory for challenge string",
+                } as SolutionMessage);
+                return;
+            }
+
+            memory = new Uint8Array(solver.exports.memory.buffer);
+            memory.set(target_bytes, target_ptr);
+
+            solution = solver.exports.solve_leaading_zeroes_challenge(
+                target_ptr,
+                target.length,
+                difficulty,
+            );
+            console.debug(`[${worker_name}]: WASM solver found nonce: ${solution}`);
+            break;
+        case ChallengeStrategy.TargetNumber:
+            const { salt } = event.data;
+            console.debug(`[${worker_name}]: recieved ${strategy} challenge: ${target}, salt: ${salt}`);
+
+            const salt_bytes = encoder.encode(salt);
+            target_bytes = encoder.encode(target);
+
+            const salt_ptr = solver.exports.malloc(salt_bytes.length);
+            if (salt_ptr === 0 || salt_ptr === null) {
+                console.error(`[${worker_name}]: Failed to allocate memory for salt string`);
+                postMessage({
+                    type: WorkerResponseType.Error,
+                    error: "Failed to allocate memory for salt string",
+                } as SolutionMessage);
+                return;
+            }
+
+            target_ptr = solver.exports.malloc(target_bytes.length);
+            if (target_ptr === 0 || target_ptr === null) {
+                console.error(`[${worker_name}]: Failed to allocate memory for target string`);
+                postMessage({
+                    type: WorkerResponseType.Error,
+                    error: "Failed to allocate memory for target string",
+                } as SolutionMessage);
+                return;
+            }
+
+            memory = new Uint8Array(solver.exports.memory.buffer);
+            memory.set(salt_bytes, salt_ptr);
+            memory.set(target_bytes, target_ptr);
+
+            solution = solver.exports.solve_target_number_challenge(
+                target_ptr,
+                target_bytes.length,
+                salt_ptr,
+                salt_bytes.length,
+            );
+            console.debug(`[${worker_name}]: WASM solver found nonce: ${solution}`);
+
+            break;
+    }
+
+    // we are just assuming that if its less than -1, its the min i32
+    if (solution < 0) {
+        return postMessage({
+            type: WorkerResponseType.Error,
+            error: "failed to solve challenge",
+        } as SolutionMessage);
+    }
+
+    postMessage({
+        type: WorkerResponseType.Solution,
+        nonce: solution === -1 ? null : solution.toString()
+    } as SolutionMessage);
+};

example-app/config.toml

@@ -1,7 +1,10 @@
-strategy = "target_number"
+strategy = "kctf"
 
 [leading_zeroes]
-difficulty = 2
+difficulty = 4
 
 [target_number]
-max_number = 192
+max_number = 10000
+
+[kctf]
+difficulty = 100

example-app/nuxt.config.ts

@@ -19,7 +19,7 @@ export default defineNuxtConfig({
             }
         },
     },
-    modules: ['@unocss/nuxt', ['nuxt-ssr-lit', { litElementPrefix: 'impost-' }]],
+    modules: ['@unocss/nuxt', ['nuxt-ssr-lit', { litElementPrefix: 'pow-' }]],
 
     nitro: {
         moduleSideEffects: ["@impost/widget"],
@@ -28,9 +28,17 @@ export default defineNuxtConfig({
         },
     },
 
+    imports: {
+        transform: {
+            // only necessary in the monorepo since vite is going out to the
+            // source of the widget and transforming it and clobbering it.
+            exclude: [/impost/],
+        }
+    },
+
     vue: {
         compilerOptions: {
-            isCustomElement: (tag) => tag.startsWith('impost-'),
+            isCustomElement: (tag) => tag.includes('pow-'),
         },
     },
 

example-app/package.json

@@ -1,5 +1,5 @@
 {
-    "name": "example-app",
+    "name": "hello-nuxt",
     "private": true,
     "type": "module",
     "scripts": {
@@ -9,13 +9,15 @@
         "preview": "nuxt preview"
     },
     "dependencies": {
-        "@impost/lib": "workspace:*",
-        "@impost/widget": "workspace:*",
+        "@lit/reactive-element": "^2.1.1",
         "js-toml": "^1.0.2",
+        "lit-element": "^4.2.1",
+        "lit-html": "^3.3.1",
         "nuxt": "latest",
         "nuxt-ssr-lit": "1.6.32",
-        "vue": "^3.5.25",
-        "zod": "^4.1.12"
+        "zod": "^4.1.12",
+        "@impost/lib": "^0.1.0",
+        "@impost/widget": "^0.1.0"
     },
     "devDependencies": {
         "@types/node": "^24.10.0",

example-app/server/api/pow/challenge.get.ts

@@ -6,19 +6,28 @@ import { CHALLENGE_TIMEOUT_MS, outstandingChallenges } from '~~/server/utils/pow
 
 export default defineEventHandler(async () => {
     let challenge_config;
+    // switch (config.strategy) {
+    //     case ChallengeStrategy.LeadingZeroes:
+    //         challenge_config = {
+    //             parameters: { expires_at: CHALLENGE_TIMEOUT_MS },
+    //             strategy: config.strategy,
+    //             difficulty: config.leading_zeroes?.difficulty!,
+    //         };
+    //         break;
+    //     case ChallengeStrategy.TargetNumber:
+    //         challenge_config = {
+    //             parameters: { expires_at: CHALLENGE_TIMEOUT_MS },
+    //             strategy: config.strategy,
+    //             max_number: config.target_number.max_number,
+    //         };
+    //         break;
+    // }
     switch (config.strategy) {
-        case ChallengeStrategy.LeadingZeroes:
+        case ChallengeStrategy.kCTF:
             challenge_config = {
                 parameters: { expires_at: CHALLENGE_TIMEOUT_MS },
                 strategy: config.strategy,
-                difficulty: config.leading_zeroes?.difficulty!,
-            };
-            break;
-        case ChallengeStrategy.TargetNumber:
-            challenge_config = {
-                parameters: { expires_at: CHALLENGE_TIMEOUT_MS },
-                strategy: config.strategy,
-                max_number: config.target_number.max_number,
+                difficulty: config.kctf.difficulty,
             };
             break;
     }
@@ -31,10 +40,10 @@ export default defineEventHandler(async () => {
         });
     }
 
-    outstandingChallenges.set(challenge.salt, {
+    outstandingChallenges.set(challenge.challenge, {
         challenge, timeout: setTimeout(() => {
-            console.log("Challenge timed out:", challenge.salt);
-            outstandingChallenges.delete(challenge.salt);
+            console.log("Challenge timed out:", challenge.challenge);
+            outstandingChallenges.delete(challenge.challenge);
         }, CHALLENGE_TIMEOUT_MS)
     });
 

example-app/server/api/pow/challenge.post.ts

@@ -4,38 +4,42 @@ import * as z from 'zod';
 import { outstandingChallenges } from '~~/server/utils/pow';
 
 const challengeSchema = z.object({
-    challenge: z.string(),
-    nonce: z.string()
+    challenge: z.string().startsWith("s."),
+    solution: z.string().startsWith("s.")
 })
 
 // post handler that takes in the challenge, and the nonce
 export default defineEventHandler(async (event) => {
+    console.log(await readBody(event));
     const body = await readValidatedBody(event, challengeSchema.safeParse);
 
     if (!body.success) {
-        const errors = z.treeifyError(body.error);
-        const error_message = Object.entries(errors.errors).map(([key, value]) => `${key}: ${value}`).join('\n');
-
         throw createError({
             statusCode: 400,
-            statusMessage: error_message
+            statusMessage: 'Validation failed'
         })
     }
 
-    let { challenge, nonce } = body.data;
+    let { challenge, solution } = body.data;
 
-    const outstanding_challenge = outstandingChallenges.get(body.data.challenge)!;
-    // always delete the challenge on a solve attempt
-    clearTimeout(outstanding_challenge.timeout);
-    outstandingChallenges.delete(challenge);
+    const outstanding_challenge = outstandingChallenges.get(challenge);
+    if (outstanding_challenge === undefined) {
+        throw createError({
+            statusCode: 400,
+            statusMessage: 'Challenge not found'
+        })
+    }
 
     // check if the challenge is valid
-    let challenge_valid = await validate_challenge(outstandingChallenges.get(challenge)!.challenge, {
-        challenge,
-        nonce,
-    });
+    const challenge_valid = await validate_challenge(outstanding_challenge.challenge, solution);
+
+    console.log("CHALLENGE VALID", challenge_valid);
 
     if (challenge_valid) {
+        // clear the challenge
+        clearTimeout(outstandingChallenges.get(challenge)!.timeout);
+        outstandingChallenges.delete(challenge);
+
         return {
             message: 'Challenge solved'
         };

example-app/server/utils/config.ts

@@ -3,26 +3,31 @@ import { load } from 'js-toml';
 import z from 'zod';
 import { ChallengeStrategy } from "@impost/lib";
 
-const LeadingZeroesSchema = z.object({
-    strategy: z.literal(ChallengeStrategy.LeadingZeroes),
-    leading_zeroes: z.object({
-        difficulty: z.number().int().min(1).max(64),
+// const LeadingZeroesSchema = z.object({
+//     strategy: z.literal(ChallengeStrategy.LeadingZeroes),
+//     leading_zeroes: z.object({
+//         difficulty: z.number().int().min(1).max(64),
+//     }),
+// });
+
+// const TargetNumberSchema = z.object({
+//     strategy: z.literal(ChallengeStrategy.TargetNumber),
+//     target_number: z.object({
+//         max_number: z.number().int().min(1).max(100_000),
+//     }),
+// });
+
+const kCTFSchema = z.object({
+    strategy: z.literal(ChallengeStrategy.kCTF),
+    kctf: z.object({
+        difficulty: z.number().int().min(1),
     }),
 });
 
-const TargetNumberSchema = z.object({
-    strategy: z.literal(ChallengeStrategy.TargetNumber),
-    target_number: z.object({
-        max_number: z.number().int().min(1).max(100_000),
-    }),
-});
-
-
 export type Config = z.infer<typeof Config>;
 
 export const Config = z.discriminatedUnion('strategy', [
-    LeadingZeroesSchema,
-    TargetNumberSchema,
+    kCTFSchema,
 ]);
 
 export let config: Config;

justfile

@@ -0,0 +1,30 @@
+wasm-opt-args := "--strip-debug --strip-dwarf --enable-tail-call --enable-bulk-memory -Oz"
+zig-build-args := "--release=fast -Dtarget=wasm32-freestanding -Dcpu=generic+bulk_memory+bulk_memory_opt+simd128+tail_call"
+
+npm-runner := "npm"
+
+[working-directory: "example-app"]
+playground: build
+    {{npm-runner}} run dev
+
+build: build-widget
+
+[working-directory: "solver"]
+build-wasm:
+    zig build {{zig-build-args}}
+    wasm-opt {{wasm-opt-args}} --enable-simd -o zig-out/bin/solver.wasm zig-out/bin/solver.wasm
+    # The server does not support simd, so we disable it here
+    wasm-opt {{wasm-opt-args}} --disable-simd -o zig-out/bin/validator.wasm zig-out/bin/validator.wasm
+
+[working-directory: "packages/lib"]
+build-lib: build-wasm
+    {{npm-runner}} install
+    {{npm-runner}} link
+    {{npm-runner}} run build
+
+[working-directory: "packages/widget"]
+build-widget: build-lib
+    {{npm-runner}} install
+    {{npm-runner}} link @impost/lib
+    {{npm-runner}} link
+    {{npm-runner}} run build

package.json

@@ -1,17 +0,0 @@
-{
-    "name": "impost-monorepo",
-    "version": "0.0.0",
-    "private": true,
-    "scripts": {
-        "build": "pnpm build:all",
-        "build:all": "pnpm build:solver && pnpm build:lib && pnpm build:widget",
-        "build:solver": "pnpm --filter solver build",
-        "build:lib": "pnpm --filter lib build",
-        "build:widget": "pnpm --filter widget build",
-        "dev:example": "pnpm --filter example-app dev"
-    },
-    "devDependencies": {
-        "typescript": "^5.0.0"
-    },
-    "packageManager": "pnpm@10.21.0+sha512.da3337267e400fdd3d479a6c68079ac6db01d8ca4f67572083e722775a796788a7a9956613749e000fac20d424b594f7a791a5f4e2e13581c5ef947f26968a40"
-}

packages/lib/src/index.ts

@@ -1,28 +1,44 @@
+import { UUID } from "uuidv7";
+
 export enum ChallengeAlgorithm {
     Argon2id = "argon2id",
 }
 
 export enum ChallengeStrategy {
+    kCTF = "kctf",
     LeadingZeroes = "leading_zeroes",
     TargetNumber = "target_number",
 }
 
 // In this case, the client will repeatedly hash a number with has until it 
 // finds a hash thaat starts with *difficulty* leading zeroes
-export interface ChallengeLeadingZeroes {
-    algorithm: ChallengeAlgorithm;
-    strategy: ChallengeStrategy.LeadingZeroes;
-    salt: string; // random string
+// export interface ChallengeLeadingZeroes {
+//     algorithm: ChallengeAlgorithm;
+//     strategy: ChallengeStrategy.LeadingZeroes;
+//     salt: string; // random string
+//     difficulty: number;
+// }
+
+// // In this case, the server generates a random number, and the client will hash
+// // the salt (a random string) + a random number until it finds a hash that is equal to challenge
+// export interface ChallengeTargetNumber {
+//     algorithm: ChallengeAlgorithm;
+//     strategy: ChallengeStrategy.TargetNumber;
+//     salt: string; // random string
+//     target: string; // hash of salt + random number
+// }
+
+export interface InnerChallengekCTF {
+    strategy: ChallengeStrategy.kCTF;
+    salt: UUID; // UUIDv7
     difficulty: number;
 }
 
-// In this case, the server generates a random number, and the client will hash
-// the salt (a random string) + a random number until it finds a hash that is equal to challenge
-export interface ChallengeTargetNumber {
-    algorithm: ChallengeAlgorithm;
-    strategy: ChallengeStrategy.TargetNumber;
-    salt: string; // random string
-    target: string; // hash of salt + random number
+export interface ChallengekCTF {
+    strategy: ChallengeStrategy.kCTF;
+    challenge: string;
 }
 
-export type Challenge = ChallengeLeadingZeroes | ChallengeTargetNumber;
+export type InnerChallenge = InnerChallengekCTF;
+
+export type Challenge = ChallengekCTF;

packages/lib/src/solver.ts

@@ -1,11 +1,12 @@
-import WASMSolverUrl from '../../solver/zig-out/bin/solver.wasm?url&inline';
-import { ChallengeStrategy, type Challenge, type ChallengeLeadingZeroes, type ChallengeTargetNumber } from '.';
+import WASMSolverUrl from '../../../solver/zig-out/bin/solver.wasm?url&inline';
 
 type WasmExports = Record<string, Function> & {
     "malloc": (byte_count: number) => number | null;
     "free": (ptr: number | null, byte_count: number) => void;
-    "solve_leaading_zeroes_challenge": (challenge_ptr: number, challenge_len: number, difficulty: number) => number;
-    "solve_target_number_challenge": (challenge_ptr: number, challenge_len: number, target_ptr: number, target_len: number) => number;
+    // "solve_leaading_zeroes_challenge": (challenge_ptr: number, challenge_len: number, difficulty: number) => number;
+    // "solve_target_number_challenge": (challenge_ptr: number, challenge_len: number, target_ptr: number, target_len:
+    // number) => number;
+    "solve": (value_ptr: number, value_len: number) => number,
     "memory": WebAssembly.Memory;
 }
 
@@ -31,75 +32,35 @@ export async function init_solver(env: SolverEnv, module: WebAssembly.Module): P
     }) as unknown as SolverModule;
 }
 
-export function solve_challenge(solver: SolverModule, challenge: Challenge): number {
-    switch (challenge.strategy) {
-        case ChallengeStrategy.LeadingZeroes:
-            return solve_leaading_zeroes_challenge(solver, challenge);
-        case ChallengeStrategy.TargetNumber:
-            return solve_target_number_challenge(solver, challenge);
-        default:
-            throw new Error("Invalid challenge strategy");
-    }
-}
+export function solve(solver: SolverModule, challenge: string): string {
+    console.log(challenge);
 
-function solve_leaading_zeroes_challenge(solver: SolverModule, challenge: ChallengeLeadingZeroes): number {
-    const { salt, difficulty } = challenge;
     const encoder = new TextEncoder();
+    const challenge_buf = encoder.encode(challenge);
 
-    const salt_bytes = encoder.encode(salt);
-
-    const salt_ptr = solver.exports.malloc(salt_bytes.length);
-    if (salt_ptr === 0 || salt_ptr === null) {
+    const challenge_ptr = solver.exports.malloc(challenge_buf.length);
+    if (challenge_ptr === 0 || challenge_ptr === null) {
         throw new Error("Failed to allocate memory for challenge string");
     }
 
     const memory = new Uint8Array(solver.exports.memory.buffer);
-    memory.set(salt_bytes, salt_ptr);
+    memory.set(challenge_buf, challenge_ptr);
 
-    const ret = solver.exports.solve_leaading_zeroes_challenge(
-        salt_ptr,
-        salt_bytes.length,
-        difficulty,
-    );
+    const ret = solver.exports.solve(challenge_ptr, challenge_buf.length);
 
-    if (ret < 0) {
+    console.log("RET", ret);
+
+    if (ret <= 0) {
         throw new Error("Failed to solve challenge");
     }
 
-    return ret;
-}
-
-function solve_target_number_challenge(solver: SolverModule, challenge: ChallengeTargetNumber): number {
-    const { salt, target } = challenge;
-    const encoder = new TextEncoder();
-
-    const salt_bytes = encoder.encode(salt);
-    const target_bytes = encoder.encode(target);
-
-    const salt_ptr = solver.exports.malloc(salt_bytes.length);
-    if (salt_ptr === 0 || salt_ptr === null) {
-        throw new Error("Failed to allocate memory for salt string");
-    }
-
-    const target_ptr = solver.exports.malloc(target_bytes.length);
-    if (target_ptr === 0 || target_ptr === null) {
-        throw new Error("Failed to allocate memory for target string");
-    }
-
-    const memory = new Uint8Array(solver.exports.memory.buffer);
-    memory.set(salt_bytes, salt_ptr);
-    memory.set(target_bytes, target_ptr);
-
-    const ret = solver.exports.solve_target_number_challenge(
-        target_ptr,
-        target_bytes.length,
-        salt_ptr,
-        salt_bytes.length,
-    );
-
-    if (ret < 0) {
-        throw new Error("Failed to solve challenge");
-    }
-
-    return ret;
+    const length = new DataView(solver.exports.memory.buffer, ret, 2).getUint16(0, true);
+    const solution = new TextDecoder().decode(solver.exports.memory.buffer.slice(ret + 2, ret + 2 + length));
+
+    console.log("SOLUTION", solution);
+    console.log("LENGTH", length);
+
+    solver.exports.free(ret, 2 + length);
+
+    return solution;
 }

packages/lib/src/validator.ts

@@ -1,12 +1,11 @@
-import { ChallengeAlgorithm, ChallengeStrategy, type Challenge, type ChallengeLeadingZeroes, type ChallengeTargetNumber } from '.';
-import WASMValidatorUrl from '../../solver/zig-out/bin/validator.wasm?url&inline';
+import { ChallengeStrategy, type Challenge, type InnerChallenge } from '.';
+import WASMValidatorUrl from '../../../solver/zig-out/bin/validator.wasm?url&inline';
+import { uuidv7obj } from 'uuidv7';
 
 type WasmExports = Record<string, Function> & {
     "malloc": (byte_count: number) => number | null;
     "free": (ptr: number | null, byte_count: number) => void;
-    "validate_leading_zeroes_challenge": (challenge_ptr: number, challenge_len: number, nonce_ptr: number, nonce_len: number, difficulty: number) => number;
-    "validate_target_number_challenge": (target_ptr: number, target_len: number, nonce_ptr: number, nonce_len: number, salt_ptr: number, salt_len: number) => number;
-    "hash": (challenge_ptr: number, challenge_len: number, nonce_ptr: number, nonce_len: number) => bigint;
+    "validate": (challenge_ptr: number, challenge_len: number, solution_ptr: number, solution_len: number) => boolean;
     "memory": WebAssembly.Memory;
 }
 
@@ -14,159 +13,92 @@ export interface ValidatorModule extends WebAssembly.Instance {
     exports: WasmExports;
 }
 
-function array_to_base64(buffer: ArrayBuffer): string {
-    return btoa(String.fromCharCode(...new Uint8Array(buffer)));
-}
-
-async function generate_leading_zeroes_challenge(parameters: Object, difficulty: number): Promise<ChallengeLeadingZeroes> {
-    let parameters_str = Object.entries(parameters).map(([key, value]) => `${key}=${value}`).join("&");
-    let salt = `${array_to_base64(crypto.getRandomValues(new Uint8Array(32)).buffer)}?${parameters_str}`;
-
-    let challenge: ChallengeLeadingZeroes = {
-        algorithm: ChallengeAlgorithm.Argon2id,
-        strategy: ChallengeStrategy.LeadingZeroes,
-        salt,
-        difficulty,
-    };
-
-    return challenge;
-}
-
-async function generate_target_number_challenge(parameters: Object, max_number: number): Promise<ChallengeTargetNumber | null> {
-    // in target number config, since we need to generate a target hash, we
-    // need to hash the salt + nonce, so the client knows what the target is
-    const validator = (await WebAssembly.instantiateStreaming(fetch(WASMValidatorUrl))).instance as unknown as ValidatorModule;
-
-    let parameters_str = Object.entries(parameters).map(([key, value]) => `${key}=${value}`).join("&");
-    let salt = `${array_to_base64(crypto.getRandomValues(new Uint8Array(32)).buffer)}?${parameters_str}`;
-    let random_number = new DataView(crypto.getRandomValues(new Uint8Array(4)).buffer).getUint32(0, true) % max_number;
-
-    const encoder = new TextEncoder();
-    const salt_bytes = encoder.encode(salt);
-    const random_number_bytes = encoder.encode(random_number.toString());
-
-    const salt_ptr = validator.exports.malloc(salt_bytes.length);
-    const random_number_ptr = validator.exports.malloc(random_number_bytes.length);
-
-    if (salt_ptr === 0 || salt_ptr === null || random_number_ptr === 0 || random_number_ptr === null) {
-        console.error("Failed to allocate memory for challenge string");
-        return null;
+function array_to_base64(buffer: ArrayBufferLike): string {
+    let binary = '';
+    const bytes = new Uint8Array(buffer);
+    for (var i = 0; i < bytes.byteLength; i++) {
+        binary += String.fromCharCode(bytes[i]);
     }
-
-    const memory = new Uint8Array(validator.exports.memory.buffer);
-    memory.set(salt_bytes, salt_ptr);
-    memory.set(random_number_bytes, random_number_ptr);
-
-    let target_blob: bigint = validator.exports.hash(salt_ptr, salt_bytes.length, random_number_ptr, random_number_bytes.length);
-    let target_ptr = Number(target_blob & BigInt(0xFFFFFFFF));
-    let target_len = Number(target_blob >> BigInt(32));
-
-    validator.exports.free(salt_ptr, salt_bytes.length);
-    validator.exports.free(random_number_ptr, random_number_bytes.length);
-
-    // do NOT use `memory` here, by this time it has almost definitely been resized and will cause errors to touch
-    let target_slice = new Uint8Array(validator.exports.memory.buffer.slice(target_ptr, target_ptr + target_len));
-    const target = new TextDecoder().decode(target_slice);
-
-    let challenge: ChallengeTargetNumber = {
-        algorithm: ChallengeAlgorithm.Argon2id,
-        strategy: ChallengeStrategy.TargetNumber,
-        salt,
-        target
-    };
-
-    return challenge;
+    return btoa(binary);
 }
 
-export interface LeadingZeroesChallengeConfig {
+export interface kCTFChallengeConfig {
     parameters: Object;
-    strategy: ChallengeStrategy.LeadingZeroes;
+    strategy: ChallengeStrategy.kCTF;
     difficulty: number;
 }
 
-export interface TargetNumberChallengeConfig {
-    parameters: Object;
-    strategy: ChallengeStrategy.TargetNumber;
-    max_number: number;
-}
+export type ChallengeConfig = kCTFChallengeConfig;
 
-export type ChallengeConfig = LeadingZeroesChallengeConfig | TargetNumberChallengeConfig;
+const VERSION = "s";
+
+async function encode_challenge(challenge: InnerChallenge, parameters: Object = {}): Promise<string> {
+    if (challenge.strategy !== ChallengeStrategy.kCTF) {
+        throw new Error("Unsupported challenge strategy");
+    }
+
+    if (challenge.difficulty < 1) {
+        throw new Error("Difficulty must be at least 1");
+    }
+
+    const difficulty_buf = new Uint8Array(4);
+    const view = new DataView(difficulty_buf.buffer);
+    view.setUint32(0, challenge.difficulty, false);
+
+    const difficulty_str = array_to_base64(difficulty_buf.buffer);
+    const salt_str = array_to_base64(challenge.salt.bytes.buffer);
+
+    // the parameters str is expected to be sliced out of the challenge via the widget before it sends it to the wasm solver.
+    let parameters_str = Object.entries(parameters).map(([key, value]) => `${key}=${value}`).join("&");
+    if (parameters_str.length > 0) {
+        parameters_str = "?" + parameters_str;
+    }
+
+    return `${VERSION}.${difficulty_str}.${salt_str}${parameters_str}`;
+}
 
 export async function generate_challenge(config: ChallengeConfig): Promise<Challenge | null> {
-    let challenge: Challenge | null = null;
-    switch (config.strategy) {
-        case ChallengeStrategy.LeadingZeroes:
-            challenge = await generate_leading_zeroes_challenge(config.parameters, config.difficulty);
-            break;
-        case ChallengeStrategy.TargetNumber:
-            challenge = await generate_target_number_challenge(config.parameters, config.max_number);
-            break;
+    if (config.difficulty < 1) {
+        throw new Error("Difficulty must be at least 1");
     }
 
-    if (challenge === null) {
-        return null;
+    const challenge: InnerChallenge = {
+        strategy: ChallengeStrategy.kCTF,
+        salt: uuidv7obj(),
+        difficulty: config.difficulty,
     }
 
-    return challenge;
+    return {
+        strategy: ChallengeStrategy.kCTF,
+        challenge: await encode_challenge(challenge),
+    };
 }
 
-export async function validate_challenge(challenge: Challenge, challenge_solution: { challenge: string, nonce: string }): Promise<boolean> {
-    const validator = (await WebAssembly.instantiateStreaming(fetch(WASMValidatorUrl))).instance as unknown as ValidatorModule
-
+export async function validate_challenge(challenge: Challenge, challenge_solution: string): Promise<boolean> {
+    const validator = (await WebAssembly.instantiateStreaming(fetch(WASMValidatorUrl), {
+        env: {
+            __log: (str_ptr: number, str_len: number) => console.log(new TextDecoder().decode(new Uint8Array(validator.exports.memory.buffer, str_ptr, str_len))),
+        }
+    })).instance as unknown as ValidatorModule
     const encoder = new TextEncoder();
+    const challenge_buf = encoder.encode(challenge.challenge);
+    const solution_buf = encoder.encode(challenge_solution);
 
-    let err;
-    let memory;
-    let nonce_bytes, nonce_ptr;
-    let target_bytes, target_ptr;
-    switch (challenge.strategy) {
-        case ChallengeStrategy.LeadingZeroes:
-            target_bytes = encoder.encode(challenge_solution.challenge);
-            nonce_bytes = encoder.encode(challenge_solution.nonce);
+    const challenge_ptr = validator.exports.malloc(challenge_buf.length);
+    const solution_ptr = validator.exports.malloc(solution_buf.length);
 
-            target_ptr = validator.exports.malloc(challenge_solution.challenge.length);
-            nonce_ptr = validator.exports.malloc(challenge_solution.nonce.length);
-
-            if (target_ptr === 0 || target_ptr === null || nonce_ptr === 0 || nonce_ptr === null) {
-                console.error("Failed to allocate memory for challenge string");
-                return false;
-            }
-
-            memory = new Uint8Array(validator.exports.memory.buffer);
-            memory.set(target_bytes, target_ptr);
-            memory.set(nonce_bytes, nonce_ptr);
-
-            err = validator.exports.validate_leading_zeroes_challenge(target_ptr, target_bytes.length, nonce_ptr, nonce_bytes.length, challenge.difficulty);
-
-            validator.exports.free(target_ptr, target_bytes.length);
-            validator.exports.free(nonce_ptr, nonce_bytes.length);
-            break;
-        case ChallengeStrategy.TargetNumber:
-            target_bytes = encoder.encode(challenge.target);
-            const salt_bytes = encoder.encode(challenge.salt);
-            nonce_bytes = encoder.encode(challenge_solution.nonce);
-
-            const salt_ptr = validator.exports.malloc(salt_bytes.length);
-            target_ptr = validator.exports.malloc(target_bytes.length);
-            nonce_ptr = validator.exports.malloc(nonce_bytes.length);
-
-            if (salt_ptr === 0 || salt_ptr === null || target_ptr === 0 || target_ptr === null || nonce_ptr === 0 || nonce_ptr === null) {
-                console.error("Failed to allocate memory for challenge string");
-                return false;
-            }
-
-            memory = new Uint8Array(validator.exports.memory.buffer);
-            memory.set(salt_bytes, salt_ptr);
-            memory.set(target_bytes, target_ptr);
-            memory.set(nonce_bytes, nonce_ptr);
-
-            err = validator.exports.validate_target_number_challenge(target_ptr, target_bytes.length, nonce_ptr, nonce_bytes.length, salt_ptr, salt_bytes.length);
-
-            validator.exports.free(salt_ptr, salt_bytes.length);
-            validator.exports.free(target_ptr, target_bytes.length);
-            validator.exports.free(nonce_ptr, nonce_bytes.length);
-            break;
+    if (challenge_ptr === 0 || challenge_ptr === null || solution_ptr === 0 || solution_ptr === null) {
+        console.error("Failed to allocate memory for challenge string");
+        return false;
     }
 
-    return err === 0;
+    const memory = new Uint8Array(validator.exports.memory.buffer);
+    memory.set(challenge_buf, challenge_ptr);
+    memory.set(solution_buf, solution_ptr);
+
+    const is_valid = validator.exports.validate(challenge_ptr, challenge.challenge.length, solution_ptr, challenge_solution.length);
+    validator.exports.free(challenge_ptr, challenge.challenge.length);
+    validator.exports.free(solution_ptr, challenge_solution.length);
+
+    return is_valid;
 }

packages/lib/vite.config.ts

@@ -18,7 +18,7 @@ export default defineConfig({
                 preserveModules: false
             }
         },
-        minify: true
+        sourcemap: true
     },
     resolve: {
         alias: {

packages/solver/package.json

@@ -1,11 +0,0 @@
-{
-    "name": "solver",
-    "description": "Zig WASM POW solver, not an actual node package, just using this so that pnpm will build it for me",
-    "version": "0.1.0",
-    "private": true,
-    "scripts": {
-        "build": "pnpm run build:wasm && pnpm run minify",
-        "build:wasm": "zig build --release=fast -Dtarget=wasm32-freestanding -Dcpu=generic+bulk_memory+bulk_memory_opt+simd128+tail_call",
-        "minify": "wasm-opt --strip-debug --strip-dwarf -O4 -o zig-out/bin/solver.wasm zig-out/bin/solver.wasm && wasm-opt --strip-debug --strip-dwarf -O4 -o zig-out/bin/validator.wasm zig-out/bin/validator.wasm"
-    }
-}

packages/solver/src/solver.zig

@@ -1,155 +0,0 @@
-const std = @import("std");
-const builtin = @import("builtin");
-
-const Allocator = std.mem.Allocator;
-const utils = @import("utils.zig");
-
-const argon2 = @import("argon2.zig");
-
-var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
-var allocator = gpa.allocator();
-
-extern fn __get_solution() i32;
-extern fn __set_solution(value: i32) void;
-extern fn __cmpxchg_solution(old: i32, new: i32) i32;
-extern fn __fetch_add_nonce(value: i32) i32;
-extern fn __log(str_ptr: usize, str_len: usize) void;
-
-fn log(comptime level: std.log.Level, comptime scope: @TypeOf(.EnumLiteral), comptime fmt: []const u8, args: anytype) void {
-    if (comptime builtin.target.cpu.arch != .wasm32) {
-        std.log.defaultLog(level, scope, fmt, args);
-        return;
-    }
-
-    const log_level_str = switch (level) {
-        .err => "Error: ",
-        .warn => "Warning: ",
-        .info => "Info: ",
-        .debug => "Debug: ",
-    };
-
-    const formatted = std.fmt.allocPrint(allocator, fmt, args) catch return;
-    const log_str = std.fmt.allocPrint(allocator, "{s}{s}", .{ log_level_str, formatted }) catch return;
-    allocator.free(formatted);
-    __log(@intFromPtr(log_str.ptr), log_str.len);
-    allocator.free(log_str);
-}
-
-pub const std_options: std.Options = .{ .logFn = log };
-var hex_encoder = utils.HexEncoder{};
-
-export fn malloc(byte_count: usize) ?*u8 {
-    const ptr = allocator.alloc(u8, byte_count) catch return null;
-    return @ptrCast(ptr.ptr);
-}
-
-export fn free(ptr: ?*anyopaque, byte_count: usize) void {
-    if (ptr) |p| {
-        const cast_ptr: [*]u8 = @ptrCast(p);
-        allocator.free(cast_ptr[0..byte_count]);
-    }
-}
-
-// returns nonce on success, -1 on failure
-// to get the error, call get_solve_error
-export fn solve_leaading_zeroes_challenge(challenge_ptr: [*]u8, challenge_len: usize, difficulty: u32) i32 {
-    const challenge_slice = challenge_ptr[0..challenge_len];
-
-    if (difficulty < 1 or difficulty > 64) {
-        std.log.err("Invalid difficulty for leading zeroes\n", .{});
-        return -1;
-    }
-
-    const max_nonce_iterations: u64 = 1_000_000_000;
-
-    // 64 + 9 digits for nonce since the max nonce is 999_999_999 (not 1 billion since nonce < max_nonce_iterations)
-    var input_buffer: []u8 = allocator.alloc(u8, challenge_len + 9) catch {
-        std.log.err("Failed to allocate memory for challenge\n", .{});
-        return -1;
-    };
-    // dont leak memory :pepega:
-    defer allocator.free(input_buffer);
-
-    @memcpy(input_buffer[0..challenge_len], challenge_slice);
-
-    var nonce = __fetch_add_nonce(1);
-
-    while (nonce < max_nonce_iterations) : (nonce = __fetch_add_nonce(1)) {
-        if (__get_solution() != -1) {
-            // solution has already been found, no point in continuing
-            return 0;
-        }
-
-        const nonce_str = std.fmt.bufPrint(input_buffer[challenge_len..], "{d}", .{nonce}) catch {
-            std.log.err("Failed to allocate memory for nonce\n", .{});
-            return -1;
-        };
-
-        const argon2_key = argon2.hash(allocator, input_buffer[0..challenge_len], input_buffer[challenge_len .. challenge_len + nonce_str.len]) catch {
-            std.log.err("Failed to hash argon2 key\n", .{});
-            return -1;
-        };
-
-        _ = hex_encoder.encode(argon2_key);
-        if (!hex_encoder.countZeroes(difficulty)) {
-            continue;
-        }
-
-        // Found a solution!
-        if (__cmpxchg_solution(-1, nonce) == -1) {
-            // we found a solution, and we are the first to do so
-            return nonce;
-        } else {
-            // we found a solution, but we are not the first to do so
-            return 0;
-        }
-    }
-
-    return -1;
-}
-
-export fn solve_target_number_challenge(target_ptr: [*]u8, target_len: usize, salt_ptr: [*]u8, salt_len: usize) i32 {
-    const target_slice = target_ptr[0..target_len];
-    const salt_slice = salt_ptr[0..salt_len];
-
-    // TODO: take in max number
-    const max_nonce_iterations: usize = 1_000_000_000;
-    const max_digits = std.math.log10(max_nonce_iterations);
-
-    var input_buffer: []u8 = allocator.alloc(u8, salt_len + max_digits) catch {
-        return -1;
-    };
-    defer allocator.free(input_buffer);
-
-    @memcpy(input_buffer[0..salt_len], salt_slice);
-
-    var nonce = __fetch_add_nonce(1);
-    while (nonce < max_nonce_iterations) : (nonce = __fetch_add_nonce(1)) {
-        if (__get_solution() != -1) {
-            return 0;
-        }
-
-        const nonce_str = std.fmt.bufPrint(input_buffer[salt_len..], "{d}", .{nonce}) catch {
-            return -1;
-        };
-
-        const argon2_key = argon2.hash(allocator, input_buffer[0..salt_len], input_buffer[salt_len .. salt_len + nonce_str.len]) catch {
-            return -1;
-        };
-
-        const hex_slice = hex_encoder.encode(argon2_key);
-
-        if (std.mem.eql(u8, target_slice, hex_slice)) {
-            // Found a solution!
-            if (__cmpxchg_solution(-1, nonce) == -1) {
-                // we found a solution, and we are the first to do so
-                return nonce;
-            } else {
-                // we found a solution, but we are not the first to do so
-                return 0;
-            }
-        }
-    }
-
-    return -1;
-}

packages/solver/src/utils.zig

@@ -1,43 +0,0 @@
-const std = @import("std");
-const Allocator = std.mem.Allocator;
-
-pub const HexEncoder = struct {
-    scratch: [64]u8 = undefined,
-    scratch_set: bool = false,
-
-    const Self = @This();
-
-    pub fn encode(self: *Self, bytes: []const u8) []u8 {
-        self.scratch_set = true;
-
-        const hex_chars = "0123456789abcdef";
-        var i: usize = 0;
-        while (i < bytes.len) : (i += 1) {
-            self.scratch[i * 2] = hex_chars[(bytes[i] >> 4)];
-            self.scratch[i * 2 + 1] = hex_chars[bytes[i] & 0x0F];
-        }
-
-        return &self.scratch;
-    }
-
-    // counts the number of leading hexidecimal zeroes in the scratch buffer
-    // which is set by encode
-    pub fn countZeroes(self: *Self, zeroes: usize) bool {
-        if (!self.scratch_set) {
-            return false;
-        }
-
-        if (zeroes > 64 or zeroes == 0) {
-            return false;
-        }
-
-        var i: usize = 0;
-        while (i < zeroes) : (i += 1) {
-            if (self.scratch[i] != '0') {
-                return false;
-            }
-        }
-
-        return true;
-    }
-};

packages/solver/src/validator.zig

@@ -1,76 +0,0 @@
-const std = @import("std");
-const Allocator = std.mem.Allocator;
-
-const argon2 = @import("argon2.zig");
-const utils = @import("utils.zig");
-
-var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
-var allocator = gpa.allocator();
-
-var hex_encoder = utils.HexEncoder{};
-
-export fn malloc(byte_count: usize) ?*u8 {
-    const ptr = allocator.alloc(u8, byte_count) catch return null;
-    return @ptrCast(ptr.ptr);
-}
-
-export fn free(ptr: ?*anyopaque, byte_count: usize) void {
-    if (ptr) |p| {
-        const cast_ptr: [*]u8 = @ptrCast(p);
-        allocator.free(cast_ptr[0..byte_count]);
-    }
-}
-
-export fn validate_leading_zeroes_challenge(challenge_ptr: [*]u8, challenge_len: usize, nonce_ptr: [*]u8, nonce_len: usize, difficulty: u32) i32 {
-    const challenge_slice = challenge_ptr[0..challenge_len];
-    const nonce_slice = nonce_ptr[0..nonce_len];
-
-    if (difficulty < 1 or difficulty > 64) {
-        return -1;
-    }
-
-    const argon2_key = argon2.hash(allocator, challenge_slice, nonce_slice) catch return -2;
-
-    _ = hex_encoder.encode(argon2_key);
-    if (!hex_encoder.countZeroes(difficulty)) {
-        return -3;
-    }
-
-    return 0;
-}
-
-export fn validate_target_number_challenge(target_ptr: [*]u8, target_len: usize, nonce_ptr: [*]u8, nonce_len: usize, salt_ptr: [*]u8, salt_len: usize) i32 {
-    const target_slice = target_ptr[0..target_len];
-    const salt_slice = salt_ptr[0..salt_len];
-    const nonce_slice = nonce_ptr[0..nonce_len];
-
-    const argon2_key = argon2.hash(allocator, salt_slice, nonce_slice) catch return -2;
-    const hex_slice = hex_encoder.encode(argon2_key);
-
-    if (!std.mem.eql(u8, target_slice, hex_slice)) {
-        return -3;
-    }
-
-    return 0;
-}
-
-export fn hash(challenge_ptr: [*]u8, challenge_len: usize, nonce_ptr: [*]u8, nonce_len: usize) u64 {
-    const challenge = challenge_ptr[0..challenge_len];
-    const nonce = nonce_ptr[0..nonce_len];
-    const argon2_key = argon2.hash(allocator, challenge, nonce) catch return 0;
-    const hex_slice = hex_encoder.encode(argon2_key);
-
-    // bs to get the compiler to not whine about hash_slice.len being a u5 annd thus cannot be shifted by 32
-    var ret: u64 = hex_slice.len;
-    ret <<= 32;
-    ret |= @intFromPtr(hex_slice.ptr);
-    return ret;
-}
-
-// pub fn main() void {
-//     const challenge = "4d7220e22a1ea588fea60000ab8874194e4c6ffd71077adbae915826c73dbf48";
-//     const nonce = "4302";
-//     const difficulty = 3;
-
-//     std.log.info("{d}", .{validate_challenge(@constCast(challenge[0..].ptr), challenge.len, @constCast(nonce[0..].ptr), nonce.len, difficulty)});
-// }

packages/widget/package-lock.json

@@ -8,9 +8,6 @@
             "name": "@impost/widget",
             "version": "0.1.0",
             "license": "BSL-1.0",
-            "dependencies": {
-                "comlink": "^4.4.2"
-            },
             "devDependencies": {
                 "@types/node": "^20.11.24",
                 "lit": "^3.1.2",
@@ -1657,11 +1654,6 @@
             "dev": true,
             "license": "MIT"
         },
-        "node_modules/comlink": {
-            "version": "4.4.2",
-            "resolved": "https://registry.npmjs.org/comlink/-/comlink-4.4.2.tgz",
-            "integrity": "sha512-OxGdvBmJuNKSCMO4NTl1L47VRp6xn2wG4F/2hYzB6tiCb709otOxtEYCSvK80PtjODfXXZu8ds+Nw5kVCjqd2g=="
-        },
         "node_modules/compare-versions": {
             "version": "6.1.1",
             "resolved": "https://registry.npmjs.org/compare-versions/-/compare-versions-6.1.1.tgz",

packages/widget/package.json

@@ -23,7 +23,6 @@
         "lit-element": "^3.1.2"
     },
     "devDependencies": {
-        "@impost/lib": "workspace:*",
         "@types/node": "^20.11.24",
         "lit": "^3.1.2",
         "lit-element": "^3.1.2",
@@ -31,7 +30,6 @@
         "tslib": "^2.6.2",
         "typescript": "^5.3.3",
         "vite": "npm:rolldown-vite@latest",
-        "vite-plugin-dts": "^4.5.4",
-        "comlink": "^4.4.2"
+        "vite-plugin-dts": "^4.5.4"
     }
 }

packages/widget/src/entry.ts

@@ -1 +1 @@
-export * from './captcha';
+export * from './pow-captcha';

packages/widget/src/pow-captcha.ts

@@ -1,15 +1,13 @@
 import { LitElement, html, css, isServer, type PropertyValues } from 'lit';
 import { customElement, property, state } from 'lit/decorators.js';
-import { type Challenge } from '@impost/lib';
+import { type ChallengeSolveRequest, type SolutionMessage, WorkerMessageType, type WorkerRequest, WorkerResponseType } from './types/worker';
+import { type Challenge, ChallengeStrategy } from '@impost/lib';
 import { get_wasm_module } from '@impost/lib/solver';
-import * as Comlink from 'comlink';
 
-import SolverWorker from './solver-worker?worker&inline';
+import ChallengeWorker from './solver-worker?worker&inline';
 
-type SolverWorkerAPI = Comlink.Remote<typeof import("./solver-worker")>;
-
-@customElement('impost-captcha')
-export class ImpostCaptcha extends LitElement {
+@customElement('pow-captcha')
+export class PowCaptcha extends LitElement {
     static override styles = css`
     :host {
         display: block;
@@ -23,6 +21,9 @@ export class ImpostCaptcha extends LitElement {
         background-color: var(--impost-widget-background-color, #070408);
         border-radius: var(--impost-widget-border-radius, 8px);
     }
+    .impost-error-icon {
+        color: var(--impost-widget-error-icon-color, #FF8117);
+    }
     .impost-main {
         display: flex;
         align-items: center;
@@ -65,13 +66,13 @@ export class ImpostCaptcha extends LitElement {
     .impost-footer div a:hover {
         text-decoration: none;
     }
+    .hidden {
+        display: none;
+    }
   `;
 
-    /// ================================================
-    ///                   Configuration
-    /// ================================================
-
 
+    // one of: "load", "focus", "submit", "off"
     @property({ type: String })
     auto: "onload" | "onfocus" | "onsubmit" | "off" = "off";
 
@@ -81,22 +82,12 @@ export class ImpostCaptcha extends LitElement {
     @property({ type: String })
     challengejson: string = '';
 
-    @property({ type: Boolean })
-    showHashrate: boolean = false;
-
-    /// ================================================
-    ///                     Internals
-    /// ================================================
-
     // needed to allow for multiple widgets on the same page if you wanted to
     // do that for some reason
-    private uid: string = Math.floor(Math.random() * 100000).toString();
-
-    private _internals: ElementInternals | null = null;
-    static formAssociated = true;
+    uid: string = Math.floor(Math.random() * 100000).toString();
 
     @state()
-    private solution: string | null = null;
+    private solution: string = '';
 
     @state()
     private challengeData: Challenge | null = null;
@@ -107,26 +98,15 @@ export class ImpostCaptcha extends LitElement {
     @state()
     private disabled: boolean = true;
 
-    @state()
-    private hashRate: number = 0;
-
-
     // stores the nonce and solution atomics
     private sab: SharedArrayBuffer = new SharedArrayBuffer(8);
 
-    private solverWorkers: SolverWorkerAPI[] | null = null;
-    private nativeWorkers: Worker[] | null = null;
-
-    private solveStartTime: number | null = null;
-    private hashRateInterval: number | null = null;
+    private solverWorkers: Worker[] | null = null;
 
     override connectedCallback() {
         super.connectedCallback();
-        this._internals = this.attachInternals();
         this.fetchChallenge();
 
-        console.log(this._internals.form);
-
         this.initWorkers();
 
         switch (this.auto) {
@@ -138,23 +118,7 @@ export class ImpostCaptcha extends LitElement {
                 break;
             case 'onsubmit':
                 if (this.parentElement?.nodeName === 'FORM') {
-                    this.parentElement.addEventListener('submit', async (ev) => {
-                        if (this.status === 'solved') {
-                            return;
-                        }
-
-                        ev.preventDefault();
-
-                        await this.solveChallenge();
-
-                        const form = this.parentElement as HTMLFormElement;
-
-                        if (form.requestSubmit) {
-                            form.requestSubmit();
-                        } else {
-                            form.submit();
-                        }
-                    });
+                    this.parentElement.addEventListener('submit', () => this.solveChallenge());
                 }
                 break;
         }
@@ -168,15 +132,10 @@ export class ImpostCaptcha extends LitElement {
 
     override disconnectedCallback() {
         super.disconnectedCallback();
-        if (this.hashRateInterval !== null) {
-            clearInterval(this.hashRateInterval);
-            this.hashRateInterval = null;
-        }
 
-        for (const worker of this.nativeWorkers || []) {
+        for (const worker of this.solverWorkers || []) {
             worker.terminate();
             this.solverWorkers = null;
-            this.nativeWorkers = null;
         }
     }
 
@@ -195,7 +154,6 @@ export class ImpostCaptcha extends LitElement {
             return;
         }
 
-        // challenge data must be provided by the user when using SSR
         if (isServer) {
             return;
         }
@@ -207,21 +165,16 @@ export class ImpostCaptcha extends LitElement {
             })
             .catch(error => {
                 console.error('Error fetching challenge:', error);
-                this.status = 'error';
+                console.error('Failed to fetch challenge');
             });
     }
 
     async initWorkers() {
         this.solverWorkers = [];
-        this.nativeWorkers = [];
 
-        const num_workers = navigator.hardwareConcurrency;
+        const num_workers = 1;
         for (let i = 0; i < num_workers; i++) {
-            const nativeWorker = new SolverWorker();
-            const comlinkWorker = Comlink.wrap<SolverWorkerAPI>(nativeWorker);
-
-            this.nativeWorkers.push(nativeWorker);
-            this.solverWorkers.push(comlinkWorker);
+            this.solverWorkers.push(new ChallengeWorker());
         }
 
         const atomics_view = new Int32Array(this.sab);
@@ -231,120 +184,213 @@ export class ImpostCaptcha extends LitElement {
         let wasm_module = await get_wasm_module();
         let worker_promises: Promise<void>[] = [];
         for (let i = 0; i < this.solverWorkers.length; i++) {
-            const solver = this.solverWorkers[i]!;
-            worker_promises.push(solver.init(wasm_module, this.sab)); // Direct call to exposed `init` method
+            console.log('Worker', i);
+            const worker = this.solverWorkers[i]!;
+
+            worker_promises.push(new Promise<void>((resolve, reject) => {
+                const message_handler = (event: MessageEvent<SolutionMessage>) => {
+                    console.log('Worker', i, 'got message', event.data);
+
+                    if (event.data.type === WorkerResponseType.Error) {
+                        console.error("Worker error:", event.data.error);
+                        reject(event.data.error);
+                    }
+
+                    if (event.data.type === WorkerResponseType.InitOk) {
+                        resolve();
+                    }
+
+                    reject(new Error("Unexpected message from worker"));
+                };
+
+                const error_handler = (error: ErrorEvent) => {
+                    console.error("Worker error:", error);
+                    reject(error);
+                };
+
+                worker.addEventListener('message', message_handler);
+                worker.addEventListener('error', error_handler);
+
+                worker.postMessage({
+                    type: WorkerMessageType.Init,
+                    module: wasm_module,
+                    sab: this.sab,
+                } as WorkerRequest);
+            }));
         }
 
         const timeoutMs = 10 * 1000;
         let timeout: number;
         const timeoutPromise = new Promise((_, reject) => {
             timeout = setTimeout(() => {
-                reject(new Error(`Function timeout after ${timeoutMs}ms`));
+                console.error('Failed to initialize workers in time');
+                this.status = 'error';
+                reject(new Error(`Function timed out after ${timeoutMs}ms`));
             }, timeoutMs);
         });
 
         await Promise.race([
-            Promise.allSettled(worker_promises).then(results => {
-                const failedInits = results.filter(r => r.status === 'rejected');
-                if (failedInits.length > 0) {
-                    console.error('Some workers failed to initialize:', failedInits);
-                    // we might want to collect all errors, and if every 
-                    // worker fails, we can throw, but carry on if only some
-                    // fail. For now, we'll just throw if any fail.
-
-                    throw new Error("One or more workers failed to initialize.");
-                }
-
+            Promise.allSettled(worker_promises).then(() => {
                 console.log('All workers initialized');
-                return;
             }),
             timeoutPromise,
         ]).then(() => {
             clearTimeout(timeout);
-        }).catch(error => {
-            clearTimeout(timeout);
-            console.error("Worker initialization failed:", error);
-            this.status = 'error';
-            throw error;
+        });
+    }
+
+    async issueChallengeToWorker(worker: Worker, request: ChallengeSolveRequest): Promise<SolutionMessage> {
+        return new Promise<SolutionMessage>((resolve, reject) => {
+            const message_handler = (event: MessageEvent<SolutionMessage>) => {
+                worker.removeEventListener('message', message_handler);
+                worker.removeEventListener('error', error_handler);
+
+                resolve(event.data);
+            };
+
+            const error_handler = (error: ErrorEvent) => {
+                worker.removeEventListener('error', error_handler);
+                worker.removeEventListener('message', message_handler);
+                console.error("Worker error:", error);
+
+                reject(error);
+            };
+
+            worker.addEventListener('message', message_handler);
+            worker.addEventListener('error', error_handler);
+
+            // switch (request.strategy) {
+            //     case ChallengeStrategy.LeadingZeroes:
+            //         worker.postMessage({
+            //             strategy: ChallengeStrategy.LeadingZeroes,
+            //             salt: request.salt,
+            //             difficulty: request.difficulty,
+            //         } as WorkerRequest);
+            //         break;
+            //     case ChallengeStrategy.TargetNumber:
+            //         worker.postMessage({
+            //             strategy: ChallengeStrategy.TargetNumber,
+            //             target: request.target,
+            //             salt: request.salt,
+            //         } as WorkerRequest);
+            //         break;
+            // }
+            switch (request.strategy) {
+                case ChallengeStrategy.kCTF:
+                    worker.postMessage({
+                        strategy: ChallengeStrategy.kCTF,
+                        challenge: request.challenge,
+                    } as WorkerRequest);
+                    break;
+            }
         });
     }
 
     async solveChallenge() {
         if (!this.challengeData || this.solverWorkers === null) {
-            // in all normal cases, this should be impossible
+            console.error('solveChallenge called before challenge is ready');
             this.status = 'error';
             return;
         }
 
-        if (this.solution !== null || this.status !== 'unsolved') {
-            // do not solve twice
+        if (this.solution !== '') {
             return;
         }
 
-        this.solveStartTime = performance.now();
-        this.hashRateInterval = setInterval(async () => {
-            const nonce = this.getCurrentWorkingNonce();
-
-            this.hashRate = (nonce / ((performance.now() - this.solveStartTime!) / 1000));
-            console.log(this.hashRate);
-        }, 250);
-
         this.dispatchEvent(new CustomEvent('impost:solve', {
-            detail: { challenge: this.challengeData, }, // empty solution
             bubbles: true,
             composed: true,
-        }));
+        }))
+
+        console.log(this.challengeData);
 
         this.status = 'solving';
-        this.solution = null;
+        this.solution = '';
 
         const atomics_view = new Int32Array(this.sab);
-        // reset atomics
         Atomics.store(atomics_view, 0, 0);
         Atomics.store(atomics_view, 1, -1);
 
+        let request: ChallengeSolveRequest;
+
+        // switch (this.challengeData.strategy) {
+        //     case ChallengeStrategy.LeadingZeroes:
+        //         request = {
+        //             strategy: ChallengeStrategy.LeadingZeroes,
+        //             salt: this.challengeData.salt,
+        //             difficulty: this.challengeData.difficulty,
+        //         };
+        //         break;
+        //     case ChallengeStrategy.TargetNumber:
+        //         request = {
+        //             strategy: ChallengeStrategy.TargetNumber,
+        //             target: this.challengeData.target,
+        //             salt: this.challengeData.salt,
+        //         };
+        //         break;
+        // }
+        switch (this.challengeData.strategy) {
+            case ChallengeStrategy.kCTF:
+                request = {
+                    strategy: ChallengeStrategy.kCTF,
+                    challenge: this.challengeData.challenge,
+                };
+                break;
+        }
+
         console.log('Sending challenge to workers...');
         // TODO: the first response is not always the solution, due to cmpxchg 
         // blocking, some workers may block on the read, and as soon as they 
         // unblock, they return 0 since the challenge is already solved.
         //
-        // We need to do a better job of tracking solvers, so if one worker
+        // TODO: We need to do a better job of tracking solvers, so if one worker
         // errors out, we only error out if all workers have errored out.
-        let worker_promises: Promise<string>[] = [];
-        for (let solver of this.solverWorkers) {
-            worker_promises.push(solver.solve_challenge(this.challengeData as Challenge));
+        let worker_promises: Promise<SolutionMessage>[] = [];
+        for (let worker of this.solverWorkers) {
+            // dispatch to all workers, func is async so it will not block
+            worker_promises.push(this.issueChallengeToWorker(worker, request));
         }
 
-        try {
-            await Promise.race(worker_promises);
+        let solution = await Promise.race(worker_promises);
 
-            // The true solution is stored in the SharedArrayBuffer.
-            this.solution = String(Atomics.load(atomics_view, 1));
-            this.status = 'solved';
-        } catch (error: any) {
-            console.error("Captcha solving failed:", error);
+        if (solution.type === WorkerResponseType.Error) {
+            console.error("Worker error:", solution.error);
             this.status = 'error';
-        } finally {
-            if (this.hashRateInterval !== null) {
-                clearInterval(this.hashRateInterval);
-                this.hashRateInterval = null;
-            }
+            return;
         }
 
-        if (this.status === 'solved') {
-            this._internals!.setFormValue(JSON.stringify({
-                challenge: this.challengeData.salt,
-                solution: this.solution,
-            }));
+        if (solution.type !== WorkerResponseType.Solution) {
+            console.error("Worker sent spurious message");
+            this.status = 'error';
+            return;
+        }
+
+        // TODO: configure if we should fetch or not
+        try {
+            await fetch(`${this.challengeUrl}/challenge`, {
+                method: 'POST',
+                body: JSON.stringify({
+                    challenge: this.challengeData.challenge,
+                    solution: solution.solution,
+                }),
+                headers: {
+                    'Content-Type': 'application/json'
+                }
+            })
+
+            this.status = 'solved';
 
             this.dispatchEvent(new CustomEvent('impost:solved', {
                 detail: {
-                    challenge: this.challengeData,
-                    solution: this.solution,
+                    challenge: this.challengeData.challenge,
+                    solution: solution.solution,
                 },
                 bubbles: true,
                 composed: true,
-            }));
+            }))
+        } catch {
+            console.error('Failed to submit solution');
+            this.status = 'error';
         }
     }
 
@@ -389,12 +435,6 @@ export class ImpostCaptcha extends LitElement {
             </div>
 
             <div class="impost-footer">
-                ${this.showHashrate && this.status === 'solving' && this.hashRate > 0 ? html`
-                    <div>
-                        <span>H/s:</span>
-                        <span>${this.hashRate.toFixed(2)}</span>
-                    </div>
-                ` : ``}
                 <div id="provider-link">
                     Protected by <a href="https://github.com/impost/pow-captcha" target="_blank">Impost</a>
                 </div>
@@ -403,9 +443,8 @@ export class ImpostCaptcha extends LitElement {
 
         <input
             type = "text"
-            name = "impost-solution"
-            id = "impost-solution-${this.uid}"
-            style="display: none;"
+            id = "impost-solution"
+            class="hidden"
             .value = ${this.solution}
         />
     `;

packages/widget/src/solver-worker.ts

@@ -1,64 +1,77 @@
 // This worker just sits on another thread and waits for message to solve
 // challenges so that we dont block the render thread
 
-import { type Challenge } from "@impost/lib";
-import { type SolverModule, init_solver, solve_challenge as libimpost_solve_challenge } from '@impost/lib/solver';
-import * as Comlink from 'comlink';
+import {
+    type WorkerRequest,
+    type SolutionMessage,
+    WorkerMessageType,
+    WorkerResponseType,
+} from "./types/worker";
+
+import { type SolverModule, init_solver, solve } from '@impost/lib/solver';
 
 let solver: SolverModule | null = null;
 
 let atomic_nonce: Int32Array | null = null;
 let atomic_solution: Int32Array | null = null;
 
-/**
- * Initializes the worker.
- * Must be called before any solve functions.
- * @param module The solver web assembly module.
- * @param sab The SharedArrayBuffer for nonce and solution.
- */
-export async function init(module: WebAssembly.Module, sab: SharedArrayBuffer): Promise<void> {
-    atomic_nonce = new Int32Array(sab, 0, 1);
-    atomic_solution = new Int32Array(sab, 4, 1);
+onmessage = async (event: MessageEvent<WorkerRequest>) => {
+    if (event.data.type === WorkerMessageType.Init) {
+        atomic_nonce = new Int32Array(event.data.sab, 0, 1);
+        atomic_solution = new Int32Array(event.data.sab, 4, 1);
+        let module = event.data.module;
 
-    try {
-        solver = await init_solver({
-            __get_solution: () => Atomics.load(atomic_solution!, 0),
-            __set_solution: (value: number) => Atomics.store(atomic_solution!, 0, value),
-            __cmpxchg_solution: (expected: number, replacement: number) => Atomics.compareExchange(atomic_solution!, 0, expected, replacement),
-            __fetch_add_nonce: (value: number) => Atomics.add(atomic_nonce!, 0, value),
-            __log: (str_ptr: number, str_len: number) => console.log(new TextDecoder().decode(new Uint8Array(solver!.exports.memory.buffer, str_ptr, str_len))),
-        }, module);
-    } catch (error: any) {
-        console.error("Worker: Failed to initialize WASM solver", error);
-        throw new Error(`Could not load WASM solver in worker: ${error.message}`);
+        try {
+            solver = await init_solver({
+                __get_solution: () => Atomics.load(atomic_solution!, 0),
+                __set_solution: (value: number) => Atomics.store(atomic_solution!, 0, value),
+                __cmpxchg_solution: (expected: number, replacement: number) => Atomics.compareExchange(atomic_solution!, 0, expected, replacement),
+                __fetch_add_nonce: (value: number) => Atomics.add(atomic_nonce!, 0, value),
+                __log: (str_ptr: number, str_len: number) => console.log(new TextDecoder().decode(new Uint8Array(solver!.exports.memory.buffer, str_ptr, str_len))),
+            }, module);
+        } catch (error: any) {
+            postMessage({
+                type: WorkerResponseType.Error,
+                error: `Could not load WASM solver: ${error.message}`,
+            } as SolutionMessage);
+            return;
+        }
+
+        if (!solver) {
+            postMessage({
+                type: WorkerResponseType.Error,
+                error: "Failed to load WASM solver",
+            } as SolutionMessage);
+            return;
+        }
+
+        postMessage({
+            type: WorkerResponseType.InitOk,
+        } as SolutionMessage);
+        return;
     }
 
     if (!solver) {
-        throw new Error("Worker: Failed to load WASM solver.");
-    }
-}
-
-/**
- * Solves a given challenge.
- * @param challenge The challenge data.
- * @returns The nonce solution on success, or throws an error.
- */
-export async function solve_challenge(challenge: Challenge): Promise<string> {
-    if (!solver || !atomic_nonce || !atomic_solution) {
-        throw new Error("WASM solver or atomics not initialized in worker. Call init() first.");
+        postMessage({
+            type: WorkerResponseType.Error,
+            error: "WASM solver not loaded",
+        } as SolutionMessage);
+        return;
     }
 
-    console.log("Worker: Solving challenge...");
-
-    const solutionNonce = libimpost_solve_challenge(solver, challenge);
-
-    if (solutionNonce < 0) {
-        throw new Error(`Worker: Failed to solve challenge. Internal code: ${solutionNonce}`);
+    let solution: string;
+    try {
+        solution = solve(solver, event.data.challenge);
+    } catch (error: any) {
+        postMessage({
+            type: WorkerResponseType.Error,
+            error: `Failed to solve challenge: ${error.message}`,
+        } as SolutionMessage);
+        return;
     }
 
-    const finalSolution = Atomics.load(atomic_solution, 0);
-    return finalSolution.toString();
-}
-
-// * Do not forget to expose functions we want to use on the main thread
-Comlink.expose({ solve_challenge, init });
+    postMessage({
+        type: WorkerResponseType.Solution,
+        solution,
+    } as SolutionMessage);
+};

packages/widget/src/types/worker.ts

@@ -0,0 +1,69 @@
+import { ChallengeStrategy } from "@impost/lib";
+
+export enum WorkerMessageType {
+    Init = "init",
+    Challenge = "challenge",
+}
+
+interface WorkerInitRequest {
+    type: WorkerMessageType.Init;
+    module: WebAssembly.Module;
+
+    sab: SharedArrayBuffer;
+}
+
+// interface ChallengeLeadingZeroesSolveRequest {
+//     strategy: ChallengeStrategy.LeadingZeroes;
+//     salt: string;
+//     difficulty: number;
+// }
+
+// interface WorkerChallengeLeadingZeroesSolveRequest extends ChallengeLeadingZeroesSolveRequest {
+//     type: WorkerMessageType.Challenge;
+// }
+
+// interface ChallengeTargetNumberSolveRequest {
+//     strategy: ChallengeStrategy.TargetNumber;
+//     target: string;
+//     salt: string;
+// }
+
+// interface WorkerChallengeTargetNumberSolveRequest extends ChallengeTargetNumberSolveRequest {
+//     type: WorkerMessageType.Challenge;
+// }
+
+interface ChallengekCTFSolveRequest {
+    strategy: ChallengeStrategy.kCTF;
+    challenge: string;
+}
+
+interface WorkerChallengekCTFSolveRequest extends ChallengekCTFSolveRequest {
+    type: WorkerMessageType.Challenge;
+}
+
+export type ChallengeSolveRequest = ChallengekCTFSolveRequest;
+type WorkerChallengeSolveRequest = WorkerChallengekCTFSolveRequest;
+
+export type WorkerRequest = WorkerInitRequest | WorkerChallengeSolveRequest;
+
+export enum WorkerResponseType {
+    Error = "error",
+    InitOk = "init_ok",
+    Solution = "solution",
+}
+
+interface ErrorMessageResponse {
+    type: WorkerResponseType.Error;
+    error: string;
+}
+
+interface SolutionMessageResponse {
+    type: WorkerResponseType.Solution;
+    solution: string;
+}
+
+interface InitOkMessageResponse {
+    type: WorkerResponseType.InitOk;
+}
+
+export type SolutionMessage = ErrorMessageResponse | SolutionMessageResponse | InitOkMessageResponse;

packages/widget/vite.config.ts

@@ -17,10 +17,13 @@ export default defineConfig({
                 dir: 'dist',
             },
         },
-        minify: true
+        // WARN: this setting has caused issues for me in the past, but now it
+        // seems to work fine. I'm not sure why, but minifying the bundle saves
+        // 5KB, and it doesnt *cause* issues, so I'm leaving it on.
+        minify: true,
     },
 
     plugins: [
-        dts()
+        dts(),
     ],
 });

pnpm-workspace.yaml

@@ -1,10 +0,0 @@
-packages:
-  - packages/*
-  - example-app/
-
-onlyBuiltDependencies:
-  - '@parcel/watcher'
-  - core-js-pure
-  - esbuild
-
-shamefully-hoist: true

solver/src/hasher.zig

@@ -2,8 +2,8 @@ const std = @import("std");
 const Allocator = std.mem.Allocator;
 
 var argon2_params = std.crypto.pwhash.argon2.Params{
-    .t = 3, // time cost
-    .m = 8192, // memory cost (in KiB)
+    .t = 4, // time cost
+    .m = 256, // memory cost (in KiB)
     .p = 1, // parallelism (this doesnt do anything because we are targeting wasm, and we do multithreading differently anyways)
 };
 
@@ -11,8 +11,21 @@ const dk_len: usize = 32; // 16 or 32 byte key
 var derived: [dk_len]u8 = undefined;
 var buffer_hash_hex: [64]u8 = undefined;
 
+fn bytesToHex(bytes: []const u8, output: []u8) void {
+    const hex_chars = "0123456789abcdef";
+    var i: usize = 0;
+    while (i < bytes.len) : (i += 1) {
+        output[i * 2] = hex_chars[(bytes[i] >> 4)];
+        output[i * 2 + 1] = hex_chars[bytes[i] & 0x0F];
+    }
+}
+
 pub fn hash(allocator: Allocator, challenge: []const u8, nonce: []const u8) ![]u8 {
     try std.crypto.pwhash.argon2.kdf(allocator, &derived, nonce, challenge, argon2_params, .argon2id);
 
-    return derived[0..];
+    var hash_bytes: [32]u8 = undefined;
+    std.crypto.hash.sha2.Sha256.hash(&derived, @ptrCast(hash_bytes[0..].ptr), .{});
+
+    bytesToHex(&hash_bytes, &buffer_hash_hex);
+    return buffer_hash_hex[0..];
 }

solver/src/kctf.zig

@@ -0,0 +1,215 @@
+// A PoW algorithm based on google's kCTF scheme
+// https://google.github.io/kctf/
+
+const std = @import("std");
+const Allocator = std.mem.Allocator;
+const assert = std.debug.assert;
+const math = std.math;
+const Int = math.big.int.Managed;
+
+var managed_one: ?Int = null;
+
+fn get_bit(n: *Int, idx: usize) !bool {
+    if (n.len() < idx / @typeInfo(usize).int.bits) {
+        return false;
+    }
+
+    var foo = try n.clone();
+    defer foo.deinit();
+
+    try foo.shiftRight(n, idx);
+    try foo.bitAnd(&foo, &managed_one.?);
+    return foo.eql(managed_one.?);
+}
+
+pub fn square_mod(n: *Int) !void {
+    const allocator = n.allocator;
+    try n.sqr(n);
+
+    var high = try Int.init(allocator);
+    defer high.deinit();
+    try high.shiftRight(n, 1279); // high = n >> 1279
+
+    var mask = try Int.init(allocator);
+    defer mask.deinit();
+
+    if (managed_one == null) {
+        managed_one = try Int.init(allocator);
+        try managed_one.?.set(1);
+    }
+
+    try mask.set(1);
+    try mask.shiftLeft(&mask, 1279);
+    try mask.sub(&mask, &managed_one.?);
+
+    try n.bitAnd(n, &mask);
+
+    try n.add(n, &high);
+
+    if (try get_bit(n, 1279)) {
+        // clear bit 1279
+        var power_of_2 = try Int.init(allocator);
+        defer power_of_2.deinit();
+        try power_of_2.set(1);
+        try power_of_2.shiftLeft(&power_of_2, 1279);
+        try n.sub(n, &power_of_2);
+
+        // *n += 1;
+        try n.add(n, &managed_one.?);
+    }
+}
+
+pub const Version = "s";
+
+pub const Challenge = struct {
+    difficulty: ?u32,
+    salt: std.math.big.int.Managed,
+
+    const Self = @This();
+
+    pub fn destroy(self: *Self, allocator: Allocator) void {
+        self.salt.deinit();
+        allocator.destroy(self);
+    }
+
+    pub fn encode(self: *Self, allocator: Allocator) ![]u8 {
+        const solution_base64_len = std.base64.standard.Encoder.calcSize(self.salt.len() * @sizeOf(usize));
+        const dest = try allocator.alloc(u8, solution_base64_len);
+        defer allocator.free(dest);
+        @memset(dest, 0);
+
+        const limbs_u8_buffer: []u8 = std.mem.sliceAsBytes(self.salt.limbs[0..self.salt.len()]);
+        const base64_str = std.base64.standard.Encoder.encode(dest, limbs_u8_buffer);
+
+        return try std.fmt.allocPrint(allocator, "{s}", .{base64_str});
+    }
+};
+
+pub fn decode(allocator: Allocator, challenge: []const u8) !*Challenge {
+    var parts = std.mem.splitAny(u8, challenge, ".");
+    if (parts.next()) |part| {
+        if (!std.mem.eql(u8, part, Version)) {
+            return error.InvalidChallenge;
+        }
+    } else {
+        return error.InvalidChallenge;
+    }
+
+    var difficulty: ?u32 = null;
+    var next_part = parts.next() orelse return error.InvalidChallenge;
+    if (parts.peek()) |_| {
+        // must be <version>.<difficulty>.<salt>
+        const difficulty_bytes = try allocator.alloc(u8, try std.base64.standard.Decoder.calcSizeForSlice(next_part));
+        defer allocator.free(difficulty_bytes);
+
+        try std.base64.standard.Decoder.decode(difficulty_bytes, next_part);
+
+        std.log.info("Decoded difficulty bytes: {any}\n", .{difficulty_bytes});
+
+        var difficulty_array: [4]u8 = .{0} ** 4;
+        if (difficulty_bytes.len > 4) {
+            const split_idx = difficulty_bytes.len - 4;
+            for (difficulty_bytes[0..split_idx]) |byte| {
+                if (byte != 0) return error.DifficultyTooLarge;
+            }
+
+            @memcpy(&difficulty_array, difficulty_bytes[split_idx..]);
+            difficulty = std.mem.readInt(u32, &difficulty_array, .big);
+        } else {
+            const start_idx = 4 - difficulty_bytes.len;
+            @memcpy(&difficulty_array, difficulty_bytes[start_idx..]);
+            difficulty = std.mem.readInt(u32, &difficulty_array, .big);
+        }
+
+        next_part = parts.next() orelse return error.InvalidChallenge;
+    }
+
+    var salt = try std.math.big.int.Managed.init(allocator);
+    errdefer salt.deinit();
+
+    const salt_str = next_part;
+    const salt_bytes_len = try std.base64.standard.Decoder.calcSizeForSlice(salt_str);
+
+    std.log.info("salt_bytes_len: {d}\n", .{salt_bytes_len});
+
+    const salt_bytes = try allocator.alloc(u8, salt_bytes_len);
+    defer allocator.free(salt_bytes);
+
+    try std.base64.standard.Decoder.decode(salt_bytes, salt_str);
+
+    std.log.info("decoded salt: {any}\n", .{salt_bytes});
+
+    const usize_salt_bytes: []align(1) usize = std.mem.bytesAsSlice(usize, salt_bytes);
+    // TODO: the bytes are being read in as little endian, but need to be read in as big endian
+    std.log.info("usize_salt_bytes: {any}\n", .{usize_salt_bytes});
+    try salt.ensureCapacity(usize_salt_bytes.len);
+    @memcpy(salt.limbs[0..usize_salt_bytes.len], usize_salt_bytes);
+    salt.setLen(usize_salt_bytes.len);
+
+    const challenge_ptr = try allocator.create(Challenge);
+    errdefer challenge_ptr.destroy(allocator);
+
+    challenge_ptr.* = Challenge{
+        .difficulty = difficulty,
+        .salt = salt,
+    };
+
+    return challenge_ptr;
+}
+
+pub fn solve(allocator: Allocator, challenge: *Challenge) ![]u8 {
+    if (challenge.difficulty == null) {
+        return error.InvalidChallenge;
+    }
+
+    for (0..challenge.difficulty.?) |_| {
+        std.log.info("Solving challenge with difficulty {d}\n", .{challenge.difficulty.?});
+        for (0..1277) |_| {
+            try square_mod(&challenge.salt);
+        }
+        try challenge.salt.bitXor(&challenge.salt, &managed_one.?);
+    }
+
+    std.log.info("solved challenge: {any}\n", .{challenge});
+
+    return try challenge.encode(allocator);
+}
+
+pub fn check(allocator: Allocator, challenge: *Challenge, solution: *Challenge) !bool {
+    std.log.info("{d}", .{challenge.difficulty.?});
+    std.log.info("{any} vs {any}\n", .{ challenge, solution });
+
+    if (challenge.difficulty == null) {
+        return error.InvalidChallenge;
+    }
+
+    if (managed_one == null) {
+        managed_one = try Int.init(allocator);
+        try managed_one.?.set(1);
+    }
+
+    for (0..challenge.difficulty.?) |_| {
+        try solution.salt.bitXor(&solution.salt, &managed_one.?);
+
+        try square_mod(&solution.salt);
+    }
+
+    std.log.info("{any} vs {any}\n", .{ challenge, solution });
+
+    if (challenge.salt.eql(solution.salt)) {
+        return true;
+    }
+
+    var foo = try std.math.big.int.Managed.initSet(allocator, 2);
+    defer foo.deinit();
+    try foo.pow(&foo, 1279);
+    try foo.sub(&foo, &managed_one.?);
+    try foo.sub(&foo, &challenge.salt);
+
+    if (foo.eql(solution.salt)) {
+        std.log.info("challenge solved!\n", .{});
+        return true;
+    }
+
+    return false;
+}

solver/src/solver.zig

@@ -0,0 +1,88 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const Allocator = std.mem.Allocator;
+
+const kCTF = @import("kctf.zig");
+
+var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
+var allocator = gpa.allocator();
+
+extern fn __log(str_ptr: usize, str_len: usize) void;
+
+fn log(comptime level: std.log.Level, comptime scope: @TypeOf(.EnumLiteral), comptime fmt: []const u8, args: anytype) void {
+    if (comptime builtin.target.cpu.arch != .wasm32) {
+        std.log.defaultLog(level, scope, fmt, args);
+        return;
+    }
+
+    const formatted = std.fmt.allocPrint(allocator, fmt, args) catch return;
+    __log(@intFromPtr(formatted.ptr), formatted.len);
+    allocator.free(formatted);
+}
+
+pub const std_options: std.Options = .{ .logFn = log };
+
+export fn malloc(byte_count: usize) ?*u8 {
+    const ptr = allocator.alloc(u8, byte_count) catch return null;
+    return @ptrCast(ptr.ptr);
+}
+
+export fn free(ptr: ?*anyopaque, byte_count: usize) void {
+    if (ptr) |p| {
+        const cast_ptr: [*]u8 = @ptrCast(p);
+        allocator.free(cast_ptr[0..byte_count]);
+    }
+}
+
+// value_ptr is a string to the entire encoded challenge string (e.g. "s.xxxxxxxxx.xxxxxxx")
+export fn solve(value_ptr: [*]u8, value_len: usize) usize {
+    const challenge_slice = value_ptr[0..value_len];
+
+    std.log.info("Solve called with challenge {s}\n", .{challenge_slice});
+
+    const challenge = kCTF.decode(allocator, challenge_slice) catch |err| {
+        std.log.info("Error decoding challenge: {s}\n", .{@errorName(err)});
+        return 0;
+    };
+    defer challenge.destroy(allocator);
+
+    std.log.info("decoded challenge {any}\n", .{challenge});
+    const solution = kCTF.solve(allocator, challenge) catch |err| {
+        std.log.info("Error solving challenge: {s}\n", .{@errorName(err)});
+        return 0;
+    };
+
+    std.log.info("Solution: {s}\n", .{solution});
+
+    const output_ptr = allocator.alloc(u8, solution.len + 4) catch return 0;
+
+    var output_slice = output_ptr[0 .. solution.len + 4];
+    if (output_slice.len - 2 > std.math.maxInt(u16)) {
+        return 0;
+    }
+    const output_len: u16 = @intCast(output_slice.len - 2);
+    // convert to little endian
+    output_slice[0] = @intCast(output_len & 0xFF); // LSB
+    output_slice[1] = @intCast(output_len >> 8); // MSB
+
+    @memcpy(output_slice[2..4], "s.");
+    @memcpy(output_slice[4 .. 4 + solution.len], solution);
+    allocator.free(solution);
+
+    return @intFromPtr(output_ptr.ptr);
+}
+
+pub fn main() anyerror!void {
+    if (comptime builtin.cpu.arch == .wasm32) return;
+
+    var args = try std.process.argsAlloc(allocator);
+    if (args.len < 2) {
+        std.log.err("Usage: zig run src/kctf.zig <challenge>", .{});
+        return;
+    }
+
+    const challenge = try kCTF.decode(allocator, args[1]);
+    const solution = try kCTF.solve(allocator, challenge);
+
+    std.log.info("Solution: {s}", .{solution});
+}

solver/src/validator.zig

@@ -0,0 +1,93 @@
+const std = @import("std");
+const builtin = @import("builtin");
+const Allocator = std.mem.Allocator;
+
+const kCTF = @import("kctf.zig");
+
+var gpa: std.heap.GeneralPurposeAllocator(.{}) = .init;
+var allocator = gpa.allocator();
+
+extern fn __log(str_ptr: usize, str_len: usize) void;
+
+fn log(comptime level: std.log.Level, comptime scope: @TypeOf(.EnumLiteral), comptime fmt: []const u8, args: anytype) void {
+    if (comptime builtin.target.cpu.arch != .wasm32) {
+        std.log.defaultLog(level, scope, fmt, args);
+        return;
+    }
+
+    const formatted = std.fmt.allocPrint(allocator, fmt, args) catch return;
+    __log(@intFromPtr(formatted.ptr), formatted.len);
+    allocator.free(formatted);
+}
+
+pub const std_options: std.Options = .{ .logFn = log };
+
+export fn malloc(byte_count: usize) ?*u8 {
+    const ptr = allocator.alloc(u8, byte_count) catch return null;
+    return @ptrCast(ptr.ptr);
+}
+
+export fn free(ptr: ?*anyopaque, byte_count: usize) void {
+    if (ptr) |p| {
+        const cast_ptr: [*]u8 = @ptrCast(p);
+        allocator.free(cast_ptr[0..byte_count]);
+    }
+}
+
+fn bytesToHex(bytes: []const u8, buf: []u8) void {
+    const hex_chars = "0123456789abcdef";
+    var i: usize = 0;
+    while (i < bytes.len) : (i += 1) {
+        buf[i * 2] = hex_chars[(bytes[i] >> 4)];
+        buf[i * 2 + 1] = hex_chars[bytes[i] & 0x0F];
+    }
+}
+
+// challenge_ptr should look like s.<difficulty>.<challenge>
+// solution_ptr should look like s.<solved_hash>
+export fn validate(challenge_ptr: [*]u8, challenge_len: usize, solution_ptr: [*]u8, solution_len: usize) bool {
+    const challenge_buf = challenge_ptr[0..challenge_len];
+    const solution_buf = solution_ptr[0..solution_len];
+
+    std.log.info("Validate called with challenge {s} and solution {s}\n", .{ challenge_buf, solution_buf });
+
+    const challenge = kCTF.decode(allocator, challenge_buf) catch return false;
+    std.log.info("decoded challenge {any}\n", .{challenge});
+    const solution = kCTF.decode(allocator, solution_buf) catch return false;
+    defer {
+        challenge.destroy(allocator);
+        solution.destroy(allocator);
+    }
+
+    std.log.info("decoded challenge and solution\n", .{});
+
+    const is_valid = kCTF.check(allocator, challenge, solution) catch return false;
+
+    return is_valid;
+}
+
+pub fn main() anyerror!void {
+    if (comptime builtin.cpu.arch == .wasm32) return;
+
+    const args = try std.process.argsAlloc(allocator);
+    if (args.len < 3) {
+        std.log.err("Usage: zig run src/validator.zig <challenge> <solution>", .{});
+        return;
+    }
+
+    const challenge = try kCTF.decode(allocator, args[1]);
+    defer challenge.destroy(allocator);
+
+    const solution = try kCTF.decode(allocator, args[2]);
+    defer solution.destroy(allocator);
+
+    std.log.info("Challenge: {any}\n", .{challenge});
+    std.log.info("Solution: {any}\n", .{solution});
+
+    const is_valid = kCTF.check(allocator, challenge, solution) catch |err| {
+        std.log.info("Error checking challenge: {s}\n", .{@errorName(err)});
+        return;
+    };
+
+    std.log.info("Is valid: {}\n", .{is_valid});
+}