@viyuni/cookie-crypto

Standalone cookie encryption/decryption utility package.

Features

• No API dependency
• AES-256-GCM authenticated encryption
• Dynamic IV by default (random IV per encryption)
• Optional custom IV / IV length
• Optional AAD support

Build

pnpm --filter @viyuni/cookie-crypto install
pnpm --filter @viyuni/cookie-crypto run build

tsdown outputs to dist/:

• dist/index.js (ESM)
• dist/index.cjs (CJS)
• dist/index.d.ts (types)

Usage

import { encryptCookie, decryptCookie, createCookieCrypto } from '@viyuni/cookie-crypto';

const secret = 'your-strong-secret';
const cookie = 'session=abc123; Path=/; HttpOnly';

const encrypted = encryptCookie(cookie, secret);
const decrypted = decryptCookie(encrypted, secret);

const cryptoBox = createCookieCrypto(secret);
const encrypted2 = cryptoBox.encrypt(cookie, { ivLength: 16 });
const decrypted2 = cryptoBox.decrypt(encrypted2);

Payload format

v1.<iv_base64url>.<ciphertext_base64url>.<tag_base64url>

Each encryption generates a new random IV by default, so repeated encryption of the same cookie yields different ciphertext.