jose/dist/browser/runtime/decrypt.js

import { concat, uint64be } from '../lib/buffer_utils.js';
import checkIvLength from '../lib/check_iv_length.js';
import checkCekLength from './check_cek_length.js';
import timingSafeEqual from './timing_safe_equal.js';
import { JOSENotSupported, JWEDecryptionFailed } from '../util/errors.js';
import crypto, { isCryptoKey } from './webcrypto.js';
import invalidKeyInput from './invalid_key_input.js';
async function cbcDecrypt(enc, cek, ciphertext, iv, tag, aad) {
    const keySize = parseInt(enc.substr(1, 3), 10);
    const encKey = await crypto.subtle.importKey('raw', cek.subarray(keySize >> 3), 'AES-CBC', false, ['decrypt']);
    const macKey = await crypto.subtle.importKey('raw', cek.subarray(0, keySize >> 3), {
        hash: { name: `SHA-${keySize << 1}` },
        name: 'HMAC',
    }, false, ['sign']);
    const macData = concat(aad, iv, ciphertext, uint64be(aad.length << 3));
    const expectedTag = new Uint8Array((await crypto.subtle.sign('HMAC', macKey, macData)).slice(0, keySize >> 3));
    let macCheckPassed;
    try {
        macCheckPassed = timingSafeEqual(tag, expectedTag);
    }
    catch (_a) {
    }
    if (!macCheckPassed) {
        throw new JWEDecryptionFailed();
    }
    let plaintext;
    try {
        plaintext = new Uint8Array(await crypto.subtle.decrypt({ iv, name: 'AES-CBC' }, encKey, ciphertext));
    }
    catch (_b) {
    }
    if (!plaintext) {
        throw new JWEDecryptionFailed();
    }
    return plaintext;
}
async function gcmDecrypt(cek, ciphertext, iv, tag, aad) {
    const encKey = cek instanceof Uint8Array
        ? await crypto.subtle.importKey('raw', cek, 'AES-GCM', false, ['decrypt'])
        : cek;
    try {
        return new Uint8Array(await crypto.subtle.decrypt({
            additionalData: aad,
            iv,
            name: 'AES-GCM',
            tagLength: 128,
        }, encKey, concat(ciphertext, tag)));
    }
    catch (_a) {
        throw new JWEDecryptionFailed();
    }
}
const decrypt = async (enc, cek, ciphertext, iv, tag, aad) => {
    if (!isCryptoKey(cek) && !(cek instanceof Uint8Array)) {
        throw new TypeError(invalidKeyInput(cek, 'CryptoKey', 'Uint8Array'));
    }
    checkCekLength(enc, cek);
    checkIvLength(enc, iv);
    switch (enc) {
        case 'A128CBC-HS256':
        case 'A192CBC-HS384':
        case 'A256CBC-HS512':
            return cbcDecrypt(enc, cek, ciphertext, iv, tag, aad);
        case 'A128GCM':
        case 'A192GCM':
        case 'A256GCM':
            return gcmDecrypt(cek, ciphertext, iv, tag, aad);
        default:
            throw new JOSENotSupported('Unsupported JWE Content Encryption Algorithm');
    }
};
export default decrypt;