27 lines
1.2 KiB
TypeScript
27 lines
1.2 KiB
TypeScript
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export async function encryptLocalStorageValue(value: unknown, key: CryptoKey): Promise<string> {
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const data = new TextEncoder().encode(JSON.stringify(value));
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const iv = crypto.getRandomValues(new Uint8Array(12));
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const encrypted = await crypto.subtle.encrypt({ name: 'AES-GCM', iv }, key, data);
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const combined = new Uint8Array(iv.length + encrypted.byteLength);
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combined.set(iv);
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combined.set(new Uint8Array(encrypted), iv.length);
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let binary = '';
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const chunkSize = 8192;
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for (let offset = 0; offset < combined.length; offset += chunkSize) {
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binary += String.fromCharCode(...combined.subarray(offset, offset + chunkSize));
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}
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return btoa(binary);
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}
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export async function decryptLocalStorageValue<T>(
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encoded: string,
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key: CryptoKey,
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): Promise<T> {
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const combined = Uint8Array.from(atob(encoded), (character) => character.charCodeAt(0));
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if (combined.length <= 12) throw new Error('Encrypted local sync record is truncated');
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const iv = combined.slice(0, 12);
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const ciphertext = combined.slice(12);
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const decrypted = await crypto.subtle.decrypt({ name: 'AES-GCM', iv }, key, ciphertext);
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return JSON.parse(new TextDecoder().decode(decrypted)) as T;
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}
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