import * as aeskw from './aeskw.js'; import * as ecdhes from './ecdhes.js'; import * as pbes2kw from './pbes2kw.js'; import * as rsaes from './rsaes.js'; import { encode as b64u } from '../util/base64url.js'; import { normalizeKey } from './normalize_key.js'; import { JOSENotSupported, JWEInvalid } from '../util/errors.js'; import { decodeBase64url } from './helpers.js'; import { generateCek, cekLength } from './content_encryption.js'; import { importJWK } from '../key/import.js'; import { exportJWK } from '../key/export.js'; import { isObject } from './type_checks.js'; import { wrap as aesGcmKwWrap, unwrap as aesGcmKwUnwrap } from './aesgcmkw.js'; import { assertCryptoKey } from './is_key_like.js'; const unsupportedAlgHeader = 'Invalid or unsupported "alg" (JWE Algorithm) header value'; function assertEncryptedKey(encryptedKey) { if (encryptedKey === undefined) throw new JWEInvalid('JWE Encrypted Key missing'); } export async function decryptKeyManagement(alg, key, encryptedKey, joseHeader, options) { switch (alg) { case 'dir': { if (encryptedKey !== undefined) throw new JWEInvalid('Encountered unexpected JWE Encrypted Key'); return key; } case 'ECDH-ES': if (encryptedKey !== undefined) throw new JWEInvalid('Encountered unexpected JWE Encrypted Key'); case 'ECDH-ES+A128KW': case 'ECDH-ES+A192KW': case 'ECDH-ES+A256KW': { if (!isObject(joseHeader.epk)) throw new JWEInvalid(`JOSE Header "epk" (Ephemeral Public Key) missing or invalid`); assertCryptoKey(key); if (!ecdhes.allowed(key)) throw new JOSENotSupported('ECDH with the provided key is not allowed or not supported by your javascript runtime'); const epk = await importJWK(joseHeader.epk, alg); assertCryptoKey(epk); let partyUInfo; let partyVInfo; if (joseHeader.apu !== undefined) { if (typeof joseHeader.apu !== 'string') throw new JWEInvalid(`JOSE Header "apu" (Agreement PartyUInfo) invalid`); partyUInfo = decodeBase64url(joseHeader.apu, 'apu', JWEInvalid); } if (joseHeader.apv !== undefined) { if (typeof joseHeader.apv !== 'string') throw new JWEInvalid(`JOSE Header "apv" (Agreement PartyVInfo) invalid`); partyVInfo = decodeBase64url(joseHeader.apv, 'apv', JWEInvalid); } const sharedSecret = await ecdhes.deriveKey(epk, key, alg === 'ECDH-ES' ? joseHeader.enc : alg, alg === 'ECDH-ES' ? cekLength(joseHeader.enc) : parseInt(alg.slice(-5, -2), 10), partyUInfo, partyVInfo); if (alg === 'ECDH-ES') return sharedSecret; assertEncryptedKey(encryptedKey); return aeskw.unwrap(alg.slice(-6), sharedSecret, encryptedKey); } case 'RSA-OAEP': case 'RSA-OAEP-256': case 'RSA-OAEP-384': case 'RSA-OAEP-512': { assertEncryptedKey(encryptedKey); assertCryptoKey(key); return rsaes.decrypt(alg, key, encryptedKey); } case 'PBES2-HS256+A128KW': case 'PBES2-HS384+A192KW': case 'PBES2-HS512+A256KW': { assertEncryptedKey(encryptedKey); if (typeof joseHeader.p2c !== 'number') throw new JWEInvalid(`JOSE Header "p2c" (PBES2 Count) missing or invalid`); const p2cLimit = options?.maxPBES2Count || 10_000; if (joseHeader.p2c > p2cLimit) throw new JWEInvalid(`JOSE Header "p2c" (PBES2 Count) out is of acceptable bounds`); if (typeof joseHeader.p2s !== 'string') throw new JWEInvalid(`JOSE Header "p2s" (PBES2 Salt) missing or invalid`); let p2s; p2s = decodeBase64url(joseHeader.p2s, 'p2s', JWEInvalid); return pbes2kw.unwrap(alg, key, encryptedKey, joseHeader.p2c, p2s); } case 'A128KW': case 'A192KW': case 'A256KW': { assertEncryptedKey(encryptedKey); return aeskw.unwrap(alg, key, encryptedKey); } case 'A128GCMKW': case 'A192GCMKW': case 'A256GCMKW': { assertEncryptedKey(encryptedKey); if (typeof joseHeader.iv !== 'string') throw new JWEInvalid(`JOSE Header "iv" (Initialization Vector) missing or invalid`); if (typeof joseHeader.tag !== 'string') throw new JWEInvalid(`JOSE Header "tag" (Authentication Tag) missing or invalid`); let iv; iv = decodeBase64url(joseHeader.iv, 'iv', JWEInvalid); let tag; tag = decodeBase64url(joseHeader.tag, 'tag', JWEInvalid); return aesGcmKwUnwrap(alg, key, encryptedKey, iv, tag); } default: { throw new JOSENotSupported(unsupportedAlgHeader); } } } export async function encryptKeyManagement(alg, enc, key, providedCek, providedParameters = {}) { let encryptedKey; let parameters; let cek; switch (alg) { case 'dir': { cek = key; break; } case 'ECDH-ES': case 'ECDH-ES+A128KW': case 'ECDH-ES+A192KW': case 'ECDH-ES+A256KW': { assertCryptoKey(key); if (!ecdhes.allowed(key)) { throw new JOSENotSupported('ECDH with the provided key is not allowed or not supported by your javascript runtime'); } const { apu, apv } = providedParameters; let ephemeralKey; if (providedParameters.epk) { ephemeralKey = (await normalizeKey(providedParameters.epk, alg)); } else { ephemeralKey = (await crypto.subtle.generateKey(key.algorithm, true, ['deriveBits'])).privateKey; } const { x, y, crv, kty } = await exportJWK(ephemeralKey); const sharedSecret = await ecdhes.deriveKey(key, ephemeralKey, alg === 'ECDH-ES' ? enc : alg, alg === 'ECDH-ES' ? cekLength(enc) : parseInt(alg.slice(-5, -2), 10), apu, apv); parameters = { epk: { x, crv, kty } }; if (kty === 'EC') parameters.epk.y = y; if (apu) parameters.apu = b64u(apu); if (apv) parameters.apv = b64u(apv); if (alg === 'ECDH-ES') { cek = sharedSecret; break; } cek = providedCek || generateCek(enc); const kwAlg = alg.slice(-6); encryptedKey = await aeskw.wrap(kwAlg, sharedSecret, cek); break; } case 'RSA-OAEP': case 'RSA-OAEP-256': case 'RSA-OAEP-384': case 'RSA-OAEP-512': { cek = providedCek || generateCek(enc); assertCryptoKey(key); encryptedKey = await rsaes.encrypt(alg, key, cek); break; } case 'PBES2-HS256+A128KW': case 'PBES2-HS384+A192KW': case 'PBES2-HS512+A256KW': { cek = providedCek || generateCek(enc); const { p2c, p2s } = providedParameters; ({ encryptedKey, ...parameters } = await pbes2kw.wrap(alg, key, cek, p2c, p2s)); break; } case 'A128KW': case 'A192KW': case 'A256KW': { cek = providedCek || generateCek(enc); encryptedKey = await aeskw.wrap(alg, key, cek); break; } case 'A128GCMKW': case 'A192GCMKW': case 'A256GCMKW': { cek = providedCek || generateCek(enc); const { iv } = providedParameters; ({ encryptedKey, ...parameters } = await aesGcmKwWrap(alg, key, cek, iv)); break; } default: { throw new JOSENotSupported(unsupportedAlgHeader); } } return { cek, encryptedKey, parameters }; }