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- 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 { checkEncCryptoKey } from '../lib/crypto_key.js';
- import invalidKeyInput from '../lib/invalid_key_input.js';
- import { types } from './is_key_like.js';
- async function cbcDecrypt(enc, cek, ciphertext, iv, tag, aad) {
- if (!(cek instanceof Uint8Array)) {
- throw new TypeError(invalidKeyInput(cek, 'Uint8Array'));
- }
- const keySize = parseInt(enc.slice(1, 4), 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: `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(enc, cek, ciphertext, iv, tag, aad) {
- let encKey;
- if (cek instanceof Uint8Array) {
- encKey = await crypto.subtle.importKey('raw', cek, 'AES-GCM', false, ['decrypt']);
- }
- else {
- checkEncCryptoKey(cek, enc, 'decrypt');
- encKey = 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, ...types, 'Uint8Array'));
- }
- checkIvLength(enc, iv);
- switch (enc) {
- case 'A128CBC-HS256':
- case 'A192CBC-HS384':
- case 'A256CBC-HS512':
- if (cek instanceof Uint8Array)
- checkCekLength(cek, parseInt(enc.slice(-3), 10));
- return cbcDecrypt(enc, cek, ciphertext, iv, tag, aad);
- case 'A128GCM':
- case 'A192GCM':
- case 'A256GCM':
- if (cek instanceof Uint8Array)
- checkCekLength(cek, parseInt(enc.slice(1, 4), 10));
- return gcmDecrypt(enc, cek, ciphertext, iv, tag, aad);
- default:
- throw new JOSENotSupported('Unsupported JWE Content Encryption Algorithm');
- }
- };
- export default decrypt;
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