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app/utils/crypto.ts

@@ -0,0 +1,95 @@
+export async function deriveKey(password: string, userId: string) {
+    const iterations = 1_000_000;
+    const saltBuffer = new TextEncoder().encode(userId);
+    const passwordBuffer = new TextEncoder().encode(password);
+
+    const baseKey = await window.crypto.subtle.importKey(
+        "raw",
+        passwordBuffer,
+        { name: "PBKDF2" },
+        false,
+        ["deriveKey"]
+    );
+
+    const derivedKey = await window.crypto.subtle.deriveKey(
+        {
+            name: "PBKDF2",
+            salt: saltBuffer,
+            iterations: iterations,
+            hash: "SHA-256",
+        },
+        baseKey,
+        {
+            name: "AES-GCM",
+            length: 256
+        },
+        true,
+        ["encrypt", "decrypt"]
+    );
+
+    const encryptionKey = await crypto.subtle.exportKey(
+        'jwk',
+        derivedKey
+    );
+
+    return encryptionKey;
+}
+
+function generateIv() {
+    return window.crypto.getRandomValues(new Uint8Array(12));
+}
+
+export function uint8ArrayToBase64(bytes: Uint8Array<ArrayBuffer>) {
+    let binaryString = '';
+    for (let i = 0; i < bytes.byteLength; i++) {
+        binaryString += String.fromCharCode(bytes[i]!);
+    }
+    return window.btoa(binaryString);
+}
+
+export function base64ToUint8Array(base64: string) {
+    const binaryString = window.atob(base64);
+    const len = binaryString.length;
+    const bytes = new Uint8Array(len);
+
+    for (let i = 0; i < len; i++) {
+        bytes[i] = binaryString.charCodeAt(i);
+    }
+
+    return bytes;
+}
+
+export async function encryptData(key: CryptoKey, plaintext: string) {
+    const iv = generateIv();
+    const data = new TextEncoder().encode(plaintext);
+
+    const encryptedContent = await window.crypto.subtle.encrypt(
+        { name: "AES-GCM", iv: iv },
+        key,
+        data
+    );
+
+    // Combine IV and Ciphertext into one Uint8Array for easy storage
+    const combined = new Uint8Array(iv.length + encryptedContent.byteLength);
+    combined.set(iv);
+    combined.set(new Uint8Array(encryptedContent), iv.length);
+
+    return combined;
+}
+
+export async function decrypt(key: CryptoKey, combinedData: Uint8Array) {
+    try {
+        const iv = combinedData.slice(0, 12);
+        const ciphertext = combinedData.slice(12);
+
+        const decryptedBuffer = await window.crypto.subtle.decrypt(
+            { name: "AES-GCM", iv: iv },
+            key,
+            ciphertext
+        );
+
+        return new TextDecoder().decode(decryptedBuffer);
+    } catch (error) {
+        throw new Error("Decryption failed. Incorrect password or corrupted data.");
+    }
+}