import { decode as b64u } from '../../util/base64url.js';
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import { decrypt } from '../../lib/content_encryption.js';
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import { decodeBase64url } from '../../lib/helpers.js';
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import { JOSEAlgNotAllowed, JOSENotSupported, JWEInvalid } from '../../util/errors.js';
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import { isDisjoint } from '../../lib/type_checks.js';
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import { isObject } from '../../lib/type_checks.js';
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import { decryptKeyManagement } from '../../lib/key_management.js';
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import { decoder, concat, encode } from '../../lib/buffer_utils.js';
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import { generateCek } from '../../lib/content_encryption.js';
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import { validateCrit } from '../../lib/validate_crit.js';
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import { validateAlgorithms } from '../../lib/validate_algorithms.js';
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import { normalizeKey } from '../../lib/normalize_key.js';
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import { checkKeyType } from '../../lib/check_key_type.js';
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import { decompress } from '../../lib/deflate.js';
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export async function flattenedDecrypt(jwe, key, options) {
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if (!isObject(jwe)) {
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throw new JWEInvalid('Flattened JWE must be an object');
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}
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if (jwe.protected === undefined && jwe.header === undefined && jwe.unprotected === undefined) {
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throw new JWEInvalid('JOSE Header missing');
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}
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if (jwe.iv !== undefined && typeof jwe.iv !== 'string') {
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throw new JWEInvalid('JWE Initialization Vector incorrect type');
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}
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if (typeof jwe.ciphertext !== 'string') {
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throw new JWEInvalid('JWE Ciphertext missing or incorrect type');
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}
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if (jwe.tag !== undefined && typeof jwe.tag !== 'string') {
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throw new JWEInvalid('JWE Authentication Tag incorrect type');
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}
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if (jwe.protected !== undefined && typeof jwe.protected !== 'string') {
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throw new JWEInvalid('JWE Protected Header incorrect type');
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}
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if (jwe.encrypted_key !== undefined && typeof jwe.encrypted_key !== 'string') {
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throw new JWEInvalid('JWE Encrypted Key incorrect type');
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}
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if (jwe.aad !== undefined && typeof jwe.aad !== 'string') {
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throw new JWEInvalid('JWE AAD incorrect type');
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}
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if (jwe.header !== undefined && !isObject(jwe.header)) {
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throw new JWEInvalid('JWE Shared Unprotected Header incorrect type');
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}
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if (jwe.unprotected !== undefined && !isObject(jwe.unprotected)) {
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throw new JWEInvalid('JWE Per-Recipient Unprotected Header incorrect type');
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}
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let parsedProt;
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if (jwe.protected) {
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try {
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const protectedHeader = b64u(jwe.protected);
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parsedProt = JSON.parse(decoder.decode(protectedHeader));
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}
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catch {
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throw new JWEInvalid('JWE Protected Header is invalid');
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}
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}
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if (!isDisjoint(parsedProt, jwe.header, jwe.unprotected)) {
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throw new JWEInvalid('JWE Protected, JWE Unprotected Header, and JWE Per-Recipient Unprotected Header Parameter names must be disjoint');
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}
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const joseHeader = {
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...parsedProt,
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...jwe.header,
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...jwe.unprotected,
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};
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validateCrit(JWEInvalid, new Map(), options?.crit, parsedProt, joseHeader);
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if (joseHeader.zip !== undefined && joseHeader.zip !== 'DEF') {
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throw new JOSENotSupported('Unsupported JWE "zip" (Compression Algorithm) Header Parameter value.');
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}
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if (joseHeader.zip !== undefined && !parsedProt?.zip) {
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throw new JWEInvalid('JWE "zip" (Compression Algorithm) Header Parameter MUST be in a protected header.');
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}
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const { alg, enc } = joseHeader;
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if (typeof alg !== 'string' || !alg) {
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throw new JWEInvalid('missing JWE Algorithm (alg) in JWE Header');
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}
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if (typeof enc !== 'string' || !enc) {
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throw new JWEInvalid('missing JWE Encryption Algorithm (enc) in JWE Header');
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}
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const keyManagementAlgorithms = options && validateAlgorithms('keyManagementAlgorithms', options.keyManagementAlgorithms);
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const contentEncryptionAlgorithms = options &&
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validateAlgorithms('contentEncryptionAlgorithms', options.contentEncryptionAlgorithms);
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if ((keyManagementAlgorithms && !keyManagementAlgorithms.has(alg)) ||
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(!keyManagementAlgorithms && alg.startsWith('PBES2'))) {
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throw new JOSEAlgNotAllowed('"alg" (Algorithm) Header Parameter value not allowed');
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}
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if (contentEncryptionAlgorithms && !contentEncryptionAlgorithms.has(enc)) {
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throw new JOSEAlgNotAllowed('"enc" (Encryption Algorithm) Header Parameter value not allowed');
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}
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let encryptedKey;
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if (jwe.encrypted_key !== undefined) {
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encryptedKey = decodeBase64url(jwe.encrypted_key, 'encrypted_key', JWEInvalid);
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}
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let resolvedKey = false;
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if (typeof key === 'function') {
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key = await key(parsedProt, jwe);
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resolvedKey = true;
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}
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checkKeyType(alg === 'dir' ? enc : alg, key, 'decrypt');
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const k = await normalizeKey(key, alg);
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let cek;
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try {
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cek = await decryptKeyManagement(alg, k, encryptedKey, joseHeader, options);
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}
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catch (err) {
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if (err instanceof TypeError || err instanceof JWEInvalid || err instanceof JOSENotSupported) {
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throw err;
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}
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cek = generateCek(enc);
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}
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let iv;
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let tag;
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if (jwe.iv !== undefined) {
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iv = decodeBase64url(jwe.iv, 'iv', JWEInvalid);
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}
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if (jwe.tag !== undefined) {
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tag = decodeBase64url(jwe.tag, 'tag', JWEInvalid);
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}
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const protectedHeader = jwe.protected !== undefined ? encode(jwe.protected) : new Uint8Array();
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let additionalData;
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if (jwe.aad !== undefined) {
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additionalData = concat(protectedHeader, encode('.'), encode(jwe.aad));
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}
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else {
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additionalData = protectedHeader;
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}
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const ciphertext = decodeBase64url(jwe.ciphertext, 'ciphertext', JWEInvalid);
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const plaintext = await decrypt(enc, cek, ciphertext, iv, tag, additionalData);
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const result = { plaintext };
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if (joseHeader.zip === 'DEF') {
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const maxDecompressedLength = options?.maxDecompressedLength ?? 250_000;
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if (maxDecompressedLength === 0) {
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throw new JOSENotSupported('JWE "zip" (Compression Algorithm) Header Parameter is not supported.');
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}
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if (maxDecompressedLength !== Infinity &&
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(!Number.isSafeInteger(maxDecompressedLength) || maxDecompressedLength < 1)) {
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throw new TypeError('maxDecompressedLength must be 0, a positive safe integer, or Infinity');
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}
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result.plaintext = await decompress(plaintext, maxDecompressedLength).catch((cause) => {
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if (cause instanceof JWEInvalid)
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throw cause;
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throw new JWEInvalid('Failed to decompress plaintext', { cause });
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});
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}
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if (jwe.protected !== undefined) {
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result.protectedHeader = parsedProt;
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}
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if (jwe.aad !== undefined) {
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result.additionalAuthenticatedData = decodeBase64url(jwe.aad, 'aad', JWEInvalid);
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}
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if (jwe.unprotected !== undefined) {
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result.sharedUnprotectedHeader = jwe.unprotected;
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}
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if (jwe.header !== undefined) {
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result.unprotectedHeader = jwe.header;
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}
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if (resolvedKey) {
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return { ...result, key: k };
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}
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return result;
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}
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