WIP: Add ML-KEM

2025-07-04 03:52:29 +00:00 · 2023-11-01 17:07:52 +01:00 · 2023-11-01 17:07:52 +01:00 · b9b5667a3f
commit b9b5667a3f
parent c7ae1d88d8
19 changed files with 539 additions and 16 deletions
--- a/package-lock.json
+++ b/package-lock.json
@ -12,6 +12,7 @@
        "@noble/ciphers": "^1.0.0",
        "@noble/curves": "^1.6.0",
        "@noble/hashes": "^1.5.0",
+        "@noble/post-quantum": "^0.2.0",
        "@openpgp/jsdoc": "^3.6.11",
        "@openpgp/seek-bzip": "^1.0.5-git",
        "@openpgp/tweetnacl": "^1.0.4-1",
@ -968,6 +969,32 @@
        "url": "https://paulmillr.com/funding/"
      }
    },
+    "node_modules/@noble/post-quantum": {
+      "version": "0.2.0",
+      "resolved": "https://registry.npmjs.org/@noble/post-quantum/-/post-quantum-0.2.0.tgz",
+      "integrity": "sha512-6dXxLXv9qCdj22zTBIRN1J8RrF+OUWQD1vJHNcqCu4JAlSo7KnaRVc+ikDPqvgky43Rn7NGQoWqeo4wv8TAJ/g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@noble/hashes": "1.4.0"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
+    "node_modules/@noble/post-quantum/node_modules/@noble/hashes": {
+      "version": "1.4.0",
+      "resolved": "https://registry.npmjs.org/@noble/hashes/-/hashes-1.4.0.tgz",
+      "integrity": "sha512-V1JJ1WTRUqHHrOSh597hURcMqVKVGL/ea3kv0gSnEdsEZ0/+VyPghM1lMNGc00z7CIQorSvbKpuJkxvuHbvdbg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">= 16"
+      },
+      "funding": {
+        "url": "https://paulmillr.com/funding/"
+      }
+    },
    "node_modules/@nodelib/fs.scandir": {
      "version": "2.1.5",
      "resolved": "https://registry.npmjs.org/@nodelib/fs.scandir/-/fs.scandir-2.1.5.tgz",
--- a/package.json
+++ b/package.json
@ -65,6 +65,7 @@
    "@noble/ciphers": "^1.0.0",
    "@noble/curves": "^1.6.0",
    "@noble/hashes": "^1.5.0",
+    "@noble/post-quantum": "^0.2.0",
    "@openpgp/jsdoc": "^3.6.11",
    "@openpgp/seek-bzip": "^1.0.5-git",
    "@openpgp/tweetnacl": "^1.0.4-1",
--- a/src/crypto/crypto.js
+++ b/src/crypto/crypto.js
@ -96,6 +96,12 @@ export async function publicKeyEncrypt(keyAlgo, symmetricAlgo, publicParams, pri
      const c = await modeInstance.encrypt(data, iv, new Uint8Array());
      return { aeadMode: new AEADEnum(aeadMode), iv, c: new ShortByteString(c) };
    }
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { eccPublicKey, mlkemPublicKey } = publicParams;
+      const { eccCipherText, mlkemCipherText, wrappedKey } = await publicKey.postQuantum.kem.encrypt(keyAlgo, eccPublicKey, mlkemPublicKey, data);
+      const C = ECDHXSymmetricKey.fromObject({ algorithm: symmetricAlgo, wrappedKey });
+      return { eccCipherText, mlkemCipherText, C };
+    }
    default:
      return [];
  }
@ -115,8 +121,8 @@ export async function publicKeyEncrypt(keyAlgo, symmetricAlgo, publicParams, pri
 * @throws {Error} on sensitive decryption error, unless `randomPayload` is given
 * @async
 */
-export async function publicKeyDecrypt(algo, publicKeyParams, privateKeyParams, sessionKeyParams, fingerprint, randomPayload) {
-  switch (algo) {
+export async function publicKeyDecrypt(keyAlgo, publicKeyParams, privateKeyParams, sessionKeyParams, fingerprint, randomPayload) {
+  switch (keyAlgo) {
    case enums.publicKey.rsaEncryptSign:
    case enums.publicKey.rsaEncrypt: {
      const { c } = sessionKeyParams;
@ -146,7 +152,7 @@ export async function publicKeyDecrypt(algo, publicKeyParams, privateKeyParams,
        throw new Error('AES session key expected');
      }
      return publicKey.elliptic.ecdhX.decrypt(
-        algo, ephemeralPublicKey, C.wrappedKey, A, k);
+        keyAlgo, ephemeralPublicKey, C.wrappedKey, A, k);
    }
    case enums.publicKey.aead: {
      const { cipher: algo } = publicKeyParams;
@ -159,6 +165,12 @@ export async function publicKeyDecrypt(algo, publicKeyParams, privateKeyParams,
      const modeInstance = await mode(algoValue, keyMaterial);
      return modeInstance.decrypt(c.data, iv, new Uint8Array());
    }
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { eccSecretKey, mlkemSecretKey } = privateKeyParams;
+      const { eccPublicKey, mlkemPublicKey } = publicKeyParams;
+      const { eccCipherText, mlkemCipherText, C } = sessionKeyParams;
+      return publicKey.postQuantum.kem.decrypt(keyAlgo, eccCipherText, mlkemCipherText, eccSecretKey, eccPublicKey, mlkemSecretKey, mlkemPublicKey, C.wrappedKey);
+    }
    default:
      throw new Error('Unknown public key encryption algorithm.');
  }
@ -230,6 +242,16 @@ export function parsePublicKeyParams(algo, bytes) {
      const digest = bytes.subarray(read, read + digestLength); read += digestLength;
      return { read: read, publicParams: { cipher: algo, digest } };
    }
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const eccPublicKey = util.readExactSubarray(bytes, read, read + getCurvePayloadSize(enums.publicKey.x25519)); read += eccPublicKey.length;
+      const mlkemPublicKey = util.readExactSubarray(bytes, read, read + 1184); read += mlkemPublicKey.length;
+      return { read, publicParams: { eccPublicKey, mlkemPublicKey } };
+    }
+    case enums.publicKey.pqc_mldsa_ed25519: {
+      const eccPublicKey = util.readExactSubarray(bytes, read, read + getCurvePayloadSize(enums.publicKey.ed25519)); read += eccPublicKey.length;
+      const mldsaPublicKey = util.readExactSubarray(bytes, read, read + 1952); read += mldsaPublicKey.length;
+      return { read, publicParams: { eccPublicKey, mldsaPublicKey } };
+    }
    default:
      throw new UnsupportedError('Unknown public key encryption algorithm.');
  }
@ -242,7 +264,7 @@ export function parsePublicKeyParams(algo, bytes) {
 * @param {Object} publicParams - (ECC and symmetric only) public params, needed to format some private params
 * @returns {{ read: Number, privateParams: Object }} Number of read bytes plus the key parameters referenced by name.
 */
-export function parsePrivateKeyParams(algo, bytes, publicParams) {
+export async function parsePrivateKeyParams(algo, bytes, publicParams) {
  let read = 0;
  switch (algo) {
    case enums.publicKey.rsaEncrypt:
@ -301,6 +323,17 @@ export function parsePrivateKeyParams(algo, bytes, publicParams) {
      const keyMaterial = bytes.subarray(read, read + keySize); read += keySize;
      return { read, privateParams: { hashSeed, keyMaterial } };
    }
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const eccSecretKey = util.readExactSubarray(bytes, read, read + getCurvePayloadSize(enums.publicKey.x25519)); read += eccSecretKey.length;
+      const mlkemSeed = util.readExactSubarray(bytes, read, read + 64); read += mlkemSeed.length;
+      const { mlkemSecretKey } = await publicKey.postQuantum.kem.mlkemExpandSecretSeed(algo, mlkemSeed);
+      return { read, privateParams: { eccSecretKey, mlkemSecretKey, mlkemSeed } };
+    }
+    case enums.publicKey.pqc_mldsa_ed25519: {
+      const eccSecretKey = util.readExactSubarray(bytes, read, read + getCurvePayloadSize(enums.publicKey.ed25519)); read += eccSecretKey.length;
+      const mldsaSecretKey = util.readExactSubarray(bytes, read, read + 4032); read += mldsaSecretKey.length;
+      return { read, privateParams: { eccSecretKey, mldsaSecretKey } };
+    }
    default:
      throw new UnsupportedError('Unknown public key encryption algorithm.');
  }
@ -364,6 +397,12 @@ export function parseEncSessionKeyParams(algo, bytes) {

      return { aeadMode, iv, c };
    }
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const eccCipherText = util.readExactSubarray(bytes, read, read + getCurvePayloadSize(enums.publicKey.x25519)); read += eccCipherText.length;
+      const mlkemCipherText = util.readExactSubarray(bytes, read, read + 1088); read += mlkemCipherText.length;
+      const C = new ECDHXSymmetricKey(); C.read(bytes.subarray(read));
+      return { eccCipherText, mlkemCipherText, C }; // eccCipherText || mlkemCipherText || len(C) || C
+    }
    default:
      throw new UnsupportedError('Unknown public key encryption algorithm.');
  }
@ -383,9 +422,20 @@ export function serializeParams(algo, params) {
    enums.publicKey.ed448,
    enums.publicKey.x448,
    enums.publicKey.aead,
-    enums.publicKey.hmac
+    enums.publicKey.hmac,
+    enums.publicKey.pqc_mlkem_x25519,
+    enums.publicKey.pqc_mldsa_ed25519
  ]);
+
+  const excludedFields = {
+    [enums.publicKey.pqc_mlkem_x25519]: new Set(['mlkemSecretKey']), // only `mlkemSeed` is serialized
+  };
+
  const orderedParams = Object.keys(params).map(name => {
+    if (excludedFields[algo]?.has(name)) {
+      return new Uint8Array();
+    }
+
    const param = params[name];
    if (!util.isUint8Array(param)) return param.write();
    return algosWithNativeRepresentation.has(algo) ? param : util.uint8ArrayToMPI(param);
@ -450,6 +500,16 @@ export async function generateParams(algo, bits, oid, symmetric) {
      const keyMaterial = generateSessionKey(symmetric);
      return createSymmetricParams(keyMaterial, new SymAlgoEnum(symmetric));
    }
+    case enums.publicKey.pqc_mlkem_x25519:
+      return publicKey.postQuantum.kem.generate(algo).then(({ eccSecretKey, eccPublicKey, mlkemSeed, mlkemSecretKey, mlkemPublicKey }) => ({
+        privateParams: { eccSecretKey, mlkemSeed, mlkemSecretKey },
+        publicParams: { eccPublicKey, mlkemPublicKey }
+      }));
+    case enums.publicKey.pqc_mldsa_ed25519:
+      return publicKey.postQuantum.signature.generate(algo).then(({ eccSecretKey, eccPublicKey, mldsaSecretKey, mldsaPublicKey }) => ({
+        privateParams: { eccSecretKey, mldsaSecretKey },
+        publicParams: { eccPublicKey, mldsaPublicKey }
+      }));
    case enums.publicKey.dsa:
    case enums.publicKey.elgamal:
      throw new Error('Unsupported algorithm for key generation.');
@ -541,6 +601,16 @@ export async function validateParams(algo, publicParams, privateParams) {
      return keySize === keyMaterial.length &&
        util.equalsUint8Array(digest, await hash.sha256(hashSeed));
    }
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { eccSecretKey, mlkemSeed } = privateParams;
+      const { eccPublicKey, mlkemPublicKey } = publicParams;
+      return publicKey.postQuantum.kem.validateParams(algo, eccPublicKey, eccSecretKey, mlkemPublicKey, mlkemSeed);
+    }
+    case enums.publicKey.pqc_mldsa_ed25519: {
+      const { eccSecretKey, mldsaSecretKey } = privateParams;
+      const { eccPublicKey, mldsaPublicKey } = publicParams;
+      return publicKey.postQuantum.signature.validateParams(algo, eccPublicKey, eccSecretKey, mldsaPublicKey, mldsaSecretKey);
+    }
    default:
      throw new Error('Unknown public key algorithm.');
  }
--- a/src/crypto/public_key/index.js
+++ b/src/crypto/public_key/index.js
@ -8,6 +8,7 @@ import * as elgamal from './elgamal';
 import * as elliptic from './elliptic';
 import * as dsa from './dsa';
 import * as hmac from './hmac';
+import * as postQuantum from './post_quantum';

 export default {
  /** @see module:crypto/public_key/rsa */
@ -19,5 +20,7 @@ export default {
  /** @see module:crypto/public_key/dsa */
  dsa: dsa,
  /** @see module:crypto/public_key/hmac */
-  hmac: hmac
+  hmac: hmac,
+  /** @see module:crypto/public_key/post_quantum */
+  postQuantum
 };
--- a/src/crypto/public_key/post_quantum/index.js
+++ b/src/crypto/public_key/post_quantum/index.js
@ -0,0 +1,5 @@
+import * as kem from './kem/index';
+
+export {
+  kem
+};
--- a/src/crypto/public_key/post_quantum/kem/ecc_kem.js
+++ b/src/crypto/public_key/post_quantum/kem/ecc_kem.js
@ -0,0 +1,62 @@
+import * as ecdhX from '../../elliptic/ecdh_x';
+import hash from '../../../hash';
+import util from '../../../../util';
+import enums from '../../../../enums';
+
+export async function generate(algo) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { A, k } = await ecdhX.generate(enums.publicKey.x25519);
+      return {
+        eccPublicKey: A,
+        eccSecretKey: k
+      };
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
+
+export async function encaps(eccAlgo, eccRecipientPublicKey) {
+  switch (eccAlgo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { ephemeralPublicKey: eccCipherText, sharedSecret: eccSharedSecret } = await ecdhX.generateEphemeralEncryptionMaterial(enums.publicKey.x25519, eccRecipientPublicKey);
+      const eccKeyShare = await hash.sha3_256(util.concatUint8Array([
+        eccSharedSecret,
+        eccCipherText,
+        eccRecipientPublicKey
+      ]));
+      return {
+        eccCipherText,
+        eccKeyShare
+      };
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
+
+export async function decaps(eccAlgo, eccCipherText, eccSecretKey, eccPublicKey) {
+  switch (eccAlgo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const eccSharedSecret = await ecdhX.recomputeSharedSecret(enums.publicKey.x25519, eccCipherText, eccPublicKey, eccSecretKey);
+      const eccKeyShare = await hash.sha3_256(util.concatUint8Array([
+        eccSharedSecret,
+        eccCipherText,
+        eccPublicKey
+      ]));
+      return eccKeyShare;
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
+
+export async function validateParams(algo, eccPublicKey, eccSecretKey) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519:
+      return ecdhX.validateParams(enums.publicKey.x25519, eccPublicKey, eccSecretKey);
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
--- a/src/crypto/public_key/post_quantum/kem/index.js
+++ b/src/crypto/public_key/post_quantum/kem/index.js
@ -0,0 +1,2 @@
+export { generate, encrypt, decrypt, validateParams } from './kem';
+export { expandSecretSeed as mlkemExpandSecretSeed } from './ml_kem';
--- a/src/crypto/public_key/post_quantum/kem/kem.js
+++ b/src/crypto/public_key/post_quantum/kem/kem.js
@ -0,0 +1,52 @@
+import * as eccKem from './ecc_kem';
+import * as mlKem from './ml_kem';
+import * as aesKW from '../../../aes_kw';
+import util from '../../../../util';
+import enums from '../../../../enums';
+
+export async function generate(algo) {
+  const { eccPublicKey, eccSecretKey } = await eccKem.generate(algo);
+  const { mlkemPublicKey, mlkemSeed, mlkemSecretKey } = await mlKem.generate(algo);
+
+  return { eccPublicKey, eccSecretKey, mlkemPublicKey, mlkemSeed, mlkemSecretKey };
+}
+
+export async function encrypt(algo, eccPublicKey, mlkemPublicKey, sessioneKeyData) {
+  const { eccKeyShare, eccCipherText } = await eccKem.encaps(algo, eccPublicKey);
+  const { mlkemKeyShare, mlkemCipherText } = await mlKem.encaps(algo, mlkemPublicKey);
+  const kek = await multiKeyCombine(algo, eccKeyShare, eccCipherText, eccPublicKey, mlkemKeyShare, mlkemCipherText, mlkemPublicKey);
+  const wrappedKey = await aesKW.wrap(enums.symmetric.aes256, kek, sessioneKeyData); // C
+  return { eccCipherText, mlkemCipherText, wrappedKey };
+}
+
+export async function decrypt(algo, eccCipherText, mlkemCipherText, eccSecretKey, eccPublicKey, mlkemSecretKey, mlkemPublicKey, encryptedSessionKeyData) {
+  const eccKeyShare = await eccKem.decaps(algo, eccCipherText, eccSecretKey, eccPublicKey);
+  const mlkemKeyShare = await mlKem.decaps(algo, mlkemCipherText, mlkemSecretKey);
+  const kek = await multiKeyCombine(algo, eccKeyShare, eccCipherText, eccPublicKey, mlkemKeyShare, mlkemCipherText, mlkemPublicKey);
+  const sessionKey = await aesKW.unwrap(enums.symmetric.aes256, kek, encryptedSessionKeyData);
+  return sessionKey;
+}
+
+async function multiKeyCombine(algo, ecdhKeyShare, ecdhCipherText, ecdhPublicKey, mlkemKeyShare, mlkemCipherText, mlkemPublicKey) {
+  const { kmac256 } = await import('@noble/hashes/sha3-addons');
+
+  const key = util.concatUint8Array([mlkemKeyShare, ecdhKeyShare]);
+  const encData = util.concatUint8Array([
+    mlkemCipherText,
+    ecdhCipherText,
+    mlkemPublicKey,
+    ecdhPublicKey,
+    new Uint8Array([algo])
+  ]);
+  const domainSeparation = util.encodeUTF8('OpenPGPCompositeKDFv1');
+
+  const kek = kmac256(key, encData, { personalization: domainSeparation }); // output length: 256 bits
+  return kek;
+}
+
+export async function validateParams(algo, eccPublicKey, eccSecretKey, mlkemPublicKey, mlkemSeed) {
+  const eccValidationPromise = eccKem.validateParams(algo, eccPublicKey, eccSecretKey);
+  const mlkemValidationPromise = mlKem.validateParams(algo, mlkemPublicKey, mlkemSeed);
+  const valid = await eccValidationPromise && await mlkemValidationPromise;
+  return valid;
+}
--- a/src/crypto/public_key/post_quantum/kem/ml_kem.js
+++ b/src/crypto/public_key/post_quantum/kem/ml_kem.js
@ -0,0 +1,72 @@
+import enums from '../../../../enums';
+import util from '../../../../util';
+import { getRandomBytes } from '../../../random';
+
+export async function generate(algo) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const mlkemSeed = getRandomBytes(64);
+      const { mlkemSecretKey, mlkemPublicKey } = await expandSecretSeed(algo, mlkemSeed);
+
+      return { mlkemSeed, mlkemSecretKey, mlkemPublicKey };
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
+
+/**
+ * Expand ML-KEM secret seed and retrieve the secret and public key material
+ * @param {module:enums.publicKey} algo - Public key algorithm
+ * @param {Uint8Array} seed - secret seed to expand
+ * @returns {Promise<{ mlkemPublicKey: Uint8Array, mlkemSecretKey: Uint8Array }>}
+ */
+export async function expandSecretSeed(algo, seed) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { ml_kem768 } = await import('@noble/post-quantum/ml-kem');
+      const { publicKey: encapsulationKey, secretKey: decapsulationKey } = ml_kem768.keygen(seed);
+
+      return { mlkemPublicKey: encapsulationKey, mlkemSecretKey: decapsulationKey };
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
+
+export async function encaps(algo, mlkemRecipientPublicKey) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { ml_kem768 } = await import('@noble/post-quantum/ml-kem');
+      const { cipherText: mlkemCipherText, sharedSecret: mlkemKeyShare } = ml_kem768.encapsulate(mlkemRecipientPublicKey);
+
+      return { mlkemCipherText, mlkemKeyShare };
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
+
+export async function decaps(algo, mlkemCipherText, mlkemSecretKey) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { ml_kem768 } = await import('@noble/post-quantum/ml-kem');
+      const mlkemKeyShare = ml_kem768.decapsulate(mlkemCipherText, mlkemSecretKey);
+
+      return mlkemKeyShare;
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
+
+export async function validateParams(algo, mlkemPublicKey, mlkemSeed) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { mlkemPublicKey: expectedPublicKey } = await expandSecretSeed(algo, mlkemSeed);
+      return util.equalsUint8Array(mlkemPublicKey, expectedPublicKey);
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
--- a/src/enums.js
+++ b/src/enums.js
@ -96,6 +96,8 @@ export default {
    ed25519: 27,
    /** Ed448 (Sign only) */
    ed448: 28,
+    /** Post-quantum ML-KEM-768 + X25519 (Encrypt only) */
+    pqc_mlkem_x25519: 105,
    /** Persistent symmetric keys: encryption algorithm */
    aead: 100,
    /** Persistent symmetric keys: authentication algorithm */
--- a/src/key/helper.js
+++ b/src/key/helper.js
@ -397,6 +397,13 @@ export function sanitizeKeyOptions(options, subkeyDefaults = {}) {
  options.sign = options.sign || false;

  switch (options.type) {
+    case 'pqc':
+      if (options.sign) {
+        throw new Error('Post-quantum signing algorithms are not yet supported.');
+      } else {
+        options.algorithm = enums.publicKey.pqc_mlkem_x25519;
+      }
+      break;
    case 'ecc': // NB: this case also handles legacy eddsa and x25519 keys, based on `options.curve`
      try {
        options.curve = enums.write(enums.curve, options.curve);
@ -474,6 +481,7 @@ export function validateEncryptionKeyPacket(keyPacket, signature, config) {
    case enums.publicKey.x25519:
    case enums.publicKey.x448:
    case enums.publicKey.aead:
+    case enums.publicKey.pqc_mlkem_x25519:
      if (!signature.keyFlags && !config.allowMissingKeyFlags) {
        throw new Error('None of the key flags is set: consider passing `config.allowMissingKeyFlags`');
      }
@ -496,7 +504,8 @@ export function validateDecryptionKeyPacket(keyPacket, signature, config) {
    case enums.publicKey.elgamal:
    case enums.publicKey.ecdh:
    case enums.publicKey.x25519:
-    case enums.publicKey.x448: {
+    case enums.publicKey.x448:
+    case enums.publicKey.pqc_mlkem_x25519: {
      const isValidSigningKeyPacket = !signature.keyFlags || (signature.keyFlags[0] & enums.keyFlags.signData) !== 0;
      if (isValidSigningKeyPacket && config.allowInsecureDecryptionWithSigningKeys) {
        // This is only relevant for RSA keys, all other signing algorithms cannot decrypt
--- a/src/packet/public_key.js
+++ b/src/packet/public_key.js
@ -138,6 +138,10 @@ class PublicKeyPacket {
      ) {
        throw new Error('Legacy curve25519 cannot be used with v6 keys');
      }
+      // The composite ML-KEM + ECDH schemes MUST be used only with v6 keys.
+      if (this.version !== 6 && this.algorithm === enums.publicKey.pqc_mlkem_x25519) {
+        throw new Error('Unexpected key version: ML-KEM algorithms can only be used with v6 keys');
+      }
      this.publicParams = publicParams;
      pos += read;

--- a/src/packet/public_key_encrypted_session_key.js
+++ b/src/packet/public_key_encrypted_session_key.js
@ -21,6 +21,12 @@ import enums from '../enums';
 import util from '../util';
 import { UnsupportedError } from './packet';

+const algosWithV3CleartextSessionKeyAlgorithm = new Set([
+  enums.publicKey.x25519,
+  enums.publicKey.x448,
+  enums.publicKey.pqc_mlkem_x25519
+]);
+
 /**
 * Public-Key Encrypted Session Key Packets (Tag 1)
 *
@ -128,7 +134,7 @@ class PublicKeyEncryptedSessionKeyPacket {
    }
    this.publicKeyAlgorithm = bytes[offset++];
    this.encrypted = crypto.parseEncSessionKeyParams(this.publicKeyAlgorithm, bytes.subarray(offset));
-    if (this.publicKeyAlgorithm === enums.publicKey.x25519 || this.publicKeyAlgorithm === enums.publicKey.x448) {
+    if (algosWithV3CleartextSessionKeyAlgorithm.has(this.publicKeyAlgorithm)) {
      if (this.version === 3) {
        this.sessionKeyAlgorithm = enums.write(enums.symmetric, this.encrypted.C.algorithm);
      } else if (this.encrypted.C.algorithm !== null) {
@ -211,7 +217,7 @@ class PublicKeyEncryptedSessionKeyPacket {

    if (this.version === 3) {
      // v3 Montgomery curves have cleartext cipher algo
-      const hasEncryptedAlgo = this.publicKeyAlgorithm !== enums.publicKey.x25519 && this.publicKeyAlgorithm !== enums.publicKey.x448;
+      const hasEncryptedAlgo = !algosWithV3CleartextSessionKeyAlgorithm.has(this.publicKeyAlgorithm);
      this.sessionKeyAlgorithm = hasEncryptedAlgo ? sessionKeyAlgorithm : this.sessionKeyAlgorithm;

      if (sessionKey.length !== crypto.getCipherParams(this.sessionKeyAlgorithm).keySize) {
@ -240,6 +246,7 @@ function encodeSessionKey(version, keyAlgo, cipherAlgo, sessionKeyData) {
      ]);
    case enums.publicKey.x25519:
    case enums.publicKey.x448:
+    case enums.publicKey.pqc_mlkem_x25519:
      return sessionKeyData;
    default:
      throw new Error('Unsupported public key algorithm');
@ -288,6 +295,7 @@ function decodeSessionKey(version, keyAlgo, decryptedData, randomSessionKey) {
    }
    case enums.publicKey.x25519:
    case enums.publicKey.x448:
+    case enums.publicKey.pqc_mlkem_x25519:
      return {
        sessionKeyAlgorithm: null,
        sessionKey: decryptedData
--- a/src/packet/secret_key.js
+++ b/src/packet/secret_key.js
@ -221,7 +221,7 @@ class SecretKeyPacket extends PublicKeyPacket {
        }
      }
      try {
-        const { read, privateParams } = crypto.parsePrivateKeyParams(this.algorithm, cleartext, this.publicParams);
+        const { read, privateParams } = await crypto.parsePrivateKeyParams(this.algorithm, cleartext, this.publicParams);
        if (read < cleartext.length) {
          throw new Error('Error reading MPIs');
        }
@ -479,7 +479,7 @@ class SecretKeyPacket extends PublicKeyPacket {
    }

    try {
-      const { privateParams } = crypto.parsePrivateKeyParams(this.algorithm, cleartext, this.publicParams);
+      const { privateParams } = await crypto.parsePrivateKeyParams(this.algorithm, cleartext, this.publicParams);
      this.privateParams = privateParams;
    } catch (err) {
      throw new Error('Error reading MPIs');
@ -532,6 +532,9 @@ class SecretKeyPacket extends PublicKeyPacket {
    )) {
      throw new Error(`Cannot generate v6 keys of type 'ecc' with curve ${curve}. Generate a key of type 'curve25519' instead`);
    }
+    if (this.version !== 6 && this.algorithm === enums.publicKey.pqc_mlkem_x25519) {
+      throw new Error(`Cannot generate v${this.version} keys of type 'pqc'. Generate a v6 key instead`);
+    }
    const { privateParams, publicParams } = await crypto.generateParams(this.algorithm, bits, curve, symmetric);
    this.privateParams = privateParams;
    this.publicParams = publicParams;
--- a/test/crypto/crypto.js
+++ b/test/crypto/crypto.js
@ -6,7 +6,7 @@ import openpgp from '../initOpenpgp.js';
 import crypto from '../../src/crypto';
 import util from '../../src/util.js';

-export default () => describe('API functional testing', function() {
+export default () => describe('API functional testing', async function() {
  const RSAPublicKeyMaterial = util.concatUint8Array([
    new Uint8Array([0x08,0x00,0xac,0x15,0xb3,0xd6,0xd2,0x0f,0xf0,0x7a,0xdd,0x21,0xb7,
      0xbf,0x61,0xfa,0xca,0x93,0x86,0xc8,0x55,0x5a,0x4b,0xa6,0xa4,0x1a,
@ -196,15 +196,15 @@ export default () => describe('API functional testing', function() {

  const algoRSA = openpgp.enums.publicKey.rsaEncryptSign;
  const RSAPublicParams = crypto.parsePublicKeyParams(algoRSA, RSAPublicKeyMaterial).publicParams;
-  const RSAPrivateParams = crypto.parsePrivateKeyParams(algoRSA, RSAPrivateKeyMaterial).privateParams;
+  const RSAPrivateParams = (await crypto.parsePrivateKeyParams(algoRSA, RSAPrivateKeyMaterial)).privateParams;

  const algoDSA = openpgp.enums.publicKey.dsa;
  const DSAPublicParams = crypto.parsePublicKeyParams(algoDSA, DSAPublicKeyMaterial).publicParams;
-  const DSAPrivateParams = crypto.parsePrivateKeyParams(algoDSA, DSAPrivateKeyMaterial).privateParams;
+  const DSAPrivateParams = (await crypto.parsePrivateKeyParams(algoDSA, DSAPrivateKeyMaterial)).privateParams;

  const algoElGamal = openpgp.enums.publicKey.elgamal;
  const elGamalPublicParams = crypto.parsePublicKeyParams(algoElGamal, elGamalPublicKeyMaterial).publicParams;
-  const elGamalPrivateParams = crypto.parsePrivateKeyParams(algoElGamal, elGamalPrivateKeyMaterial).privateParams;
+  const elGamalPrivateParams = (await crypto.parsePrivateKeyParams(algoElGamal, elGamalPrivateKeyMaterial)).privateParams;

  const data = util.stringToUint8Array('foobar');

--- a/test/crypto/index.js
+++ b/test/crypto/index.js
@ -14,6 +14,7 @@ import testEAX from './eax';
 import testOCB from './ocb';
 import testRSA from './rsa';
 import testValidate from './validate';
+import testPQC from './postQuantum';

 export default () => describe('Crypto', function () {
  testBigInteger();
@ -32,4 +33,5 @@ export default () => describe('Crypto', function () {
  testOCB();
  testRSA();
  testValidate();
+  testPQC();
 });
--- a/test/crypto/postQuantum.js
+++ b/test/crypto/postQuantum.js
@ -0,0 +1,158 @@
+import { use as chaiUse, expect } from 'chai';
+import chaiAsPromised from 'chai-as-promised'; // eslint-disable-line import/newline-after-import
+chaiUse(chaiAsPromised);
+
+import openpgp from '../initOpenpgp.js';
+import { generateParams, publicKeyEncrypt, publicKeyDecrypt } from '../../src/crypto/crypto.js';
+
+export default () => describe('PQC', function () {
+  it('ML-KEM + X25519 - Generate/encrypt/decrypt', async function () {
+    const sessionKey = { data: new Uint8Array(16).fill(1), algorithm: 'aes128' };
+
+    const { privateParams, publicParams } = await generateParams(openpgp.enums.publicKey.pqc_mlkem_x25519);
+    const encryptedSessionKeyParams = await publicKeyEncrypt(openpgp.enums.publicKey.pqc_mlkem_x25519, undefined, publicParams, null, sessionKey.data);
+    const decryptedSessionKey = await publicKeyDecrypt(openpgp.enums.publicKey.pqc_mlkem_x25519, publicParams, privateParams, encryptedSessionKeyParams);
+    expect(decryptedSessionKey).to.deep.equal(sessionKey.data);
+  });
+
+  it('ML-KEM + X25519 - private key is correctly serialized using the seed instead of the expanded secret key material', async function () {
+    const armoredKey = `-----BEGIN PGP PRIVATE KEY BLOCK-----
+
+xUsGUdDGgBsAAAAgoqT/71tSJR8iwTTL04KHMCQPkA/hzws9IS9XIOaDeCQADJT8
+QsDoLSnhKcdIiebWP4SjTjripGF8Ts4ToMFQEMfCrwYfGwoAAABABYJR0MaAAwsJ
+BwMVCggCFgACmwMCHgkioQZvmMbg5VVdnVgHJHsuCi6TZqsB2ingw/HQ6kw4sTQz
+8QUnCQIHAgAAAABTCCAcorV7OTWoI+oc6cJHH7sQwt58r/zl67/IGhs4IriTdJDo
+zEDjgfDQ+xdUnlNDAH26XFsCpuZlViHCWx7d2+UHYSl5RoXSl7nUJZwXD+Q14pJe
+pXhruANfqpjih0JfA7NLlBRQyB1c2VyIChUZXN0IEtleSkgPHBxYy10ZXN0LWtl
+eUBleGFtcGxlLmNvbT7CmwYTGwoAAAAsBYJR0MaAAhkBIqEGb5jG4OVVXZ1YByR7
+Lgouk2arAdop4MPx0OpMOLE0M/EAAAAAdU0gQGuJLou9irG3sTNROnX/x4zsskxb
+kkpcBQAzEVrH9u/T8HsDJwodnFZSoPvvvrJ6L64wItfdB6t4zAzd0YL76vTn+V4r
+zIADNDy4WyqTeysUzJDQQDvLpuOJ2uK2uoIAx8RrBlHQxoBpAAAEwLnXFoEjTQ/Z
+ow5/AEqq8vXgv0Kkvz3m9FSpXip7+MsTAVhfO8fOLsy2grZ1BZl0q2rBaRfPv/jF
+4Fpq4lpfUdlZ8QCZ6nB/zGtmYAcQQ3qWjCZS8VJB6oC7hHoGOUOkRxIhZ5kaa9sy
+juwe97eLz3l/HFwJOVZCj5ROpkCUBgW+7mwnqxCOWkl1A/gd9moaIFZhcPKVkxEn
+ErYrRmGs0tzKaoBfejetTWMlw8bLQGWq+hC+wQBfSzNs1bmt2xO08DxZFZFyxSkI
+xDUy/doh8HlWbdg65zwbZgC9Xfq1RAgpj2AT38MarlElJYqqpdgsI8pz0Qyg9rUp
+I1iJRaIToNBzpBWyKkGC+hwyrgTNXRhANQZK8pkKMXGQffo93jJiBquiF7t8QFIE
+SiJhiCrByCyCagpLhfG3/uQ4aNAxMhspK6amFAONLGwFLIVJIYwJBgtJstJSAOO5
+F4eSdYOVTsc015bNVWHD6aBG6RdInvEalRYA2vo43kJPJpXOWbGxrSN29fc4D4KM
+qBQ11zuHwxcoUxvLoGlHF5xNU7skSsG8VKBz4suqagqLoWgMJkxs17Mj+/YNt/Uo
+6cMBmOC6Dkgz1dIAQPCS93VRy5RnZ/ksOwNvojZrISG2qjK4zdM3oSbF6OQNpLst
+GGajRpcrOzWJgXZ1w3ddZwll2DuY9/k4SypuritMljCh8EVb8YK5T1SmrEx4MZcU
+eFE5M4uLdwWrvOeOPNJWn2OimJYW25q9X3a7cocItKQUL6Rog9WYzIeuyleATUlG
+9kQarVZ9vLLLBpfFXdmuS6nIx0NIPYqrsktYKWkbMYimRRwJp8OUbXu/E9TB0tG5
+48NVYNVeBQSrgGK9cnAJSPVd1yiXivCzUTRZytCUrFeA6FUVJyOF0gFR5BIkQhcj
+6zao5TdhFoURG/VI2ok42xtvK2MIdUGSecCN8cqUUclNe8YFVZRGUwiAapJTzvpF
+kzO6otd99eJbuPyagjG6BadalZkuntllEzF3LamcllsgGMZkfjm3Y+df6KiStNlG
+jXXL7oEXeRgSnWWhccVu/jot4JGoFKMK/UHBapG7GDuVKrWcNRiSHdZ09yJDxqEY
+ZkEmESdzX7AB6nKN1yi0e2NChGgh2Ag5TTSfmVFHrPUytMBD7+VLLgfCn9XMiezN
+FzdKwCUMWybF1fpur7aG5JalAEaJCvMhw4l8ovJGfBEV4rMvVwgb88svQTc3hIWV
+0VNCYfSWkvxXy4AXeFQ1p6sKP4pt9wphdTo+fYm5krMQK7HHsixxFpzA9UNy7jxp
+y8Wt+rKPc1Rk4wkPDPlziHmCqyOQoBQIqywyYlB0SJpZ7qgY4miGkMu4BNujOcoI
+HuaV1uS6Ax0dko2ycvC4zODUrahkKg8ZRPNhLmq05h7uTGjsudQ5iWQ7JKzUvPC
+IjyLVZFqA/af22t6m8oZ/ZefCkgAHRAdGZGZvbxEUYNG3+U8uNqNIpV3oGFefKGt
+dtq8b5HEp9xUDOOOPfVP3OSicnpI0FZV7IaTSRemrsFLV9UPeKo8jeyDFJQCvnQm
+M5ygZYmysEiTmKnNX3I7xjhOXtkHGdsF/eatr8BoVWPQqqslLuFQ7bvNDj+JrFhp
+H7SnPRs8wf0APxvBELBWHS358MzYhgHl2qlB98eNlpYONMLC1OKwcdZtBaQLK1mS
+0E3CFsyhm8aNsed5h3INCONDDB69NDnKcECHyEHEmi80B3PrTSvQEhu86Icku7kE
+ci7WflvsjTyVwpsGGBsKAAAALAWCUdDGgAKbDCKhBm+YxuDlVV2dWAckey4KLpNm
+qwHaKeDD8dDqTDixNDPxAAAAANrrIF2vwK+ev6toBw/VGv6eWcvSqr1cCaNXR+z2
+R7sK+lxrgTGbHvqDFrevkCwv1wtJ2AY6uTkFzMTRN8ZafNdUc8oeR3FbfVNO0Phv
+BoWQifC9dbHD5JNv0/6CMXFZagQABA==
+-----END PGP PRIVATE KEY BLOCK-----`;
+
+    const { data: expectedBinaryKey } = await openpgp.unarmor(armoredKey);
+
+    const privateKey = await openpgp.readKey({ armoredKey });
+    expect(privateKey.write()).to.deep.equal(expectedBinaryKey);
+  });
+
+  it('ML-KEM + X25519 - Test vector', async function () {
+    const armoredMessage = `-----BEGIN PGP MESSAGE-----
+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+yRdjjPV7A+exaF/WgAszi+nD/Zka0xIE3g1nCCSRn27NAtrM4jaNHlKg4DZNAC9u
+3dsfp/lAeSjDHjkLzOQep10o7Gg+1qFvNwGjOvHCX+LyVEcGIlH1dF+JjfZobWMr
+0sBWAgkCDDhxVuabuQ83wJb46Gor24w4/x4ugBmr7KrjzM14lyjnB8uDnTpkfpoB
+L5vCzO7FQfnbUWha456roBnRAOUhcqGhdqTPChnrt/ie/PUSfWZlZZh9aS+U50eK
+WGIJER2n2A1WfEnYfy155ipf3z1D+ritS9p7hzlVOQpb/xdVHnga9gfrpWljyX0L
+YRIL7wh5YjHL940kwgDtA9ZWZ8R3PLPkgOE7Jw/xUTz+QXqRK4R9SubGttmoQy7Y
+liWLjUnl5sbm/rsSqmAHdOdz4WYdwWO5eJoJ3/rH0uGZQEHQq6U/iYidTHp+OS8h
+Ww4/1zLtOw89HhwLpSN0vk87TV3ZgYVTZlVFwOOEKasNf9VhWIvFS48=
+-----END PGP MESSAGE-----`;
+
+    const privateKey = await openpgp.readKey({ armoredKey: `-----BEGIN PGP PRIVATE KEY BLOCK-----
+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+6cMBmOC6Dkgz1dIAQPCS93VRy5RnZ/ksOwNvojZrISG2qjK4zdM3oSbF6OQNpLst
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+9kQarVZ9vLLLBpfFXdmuS6nIx0NIPYqrsktYKWkbMYimRRwJp8OUbXu/E9TB0tG5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+-----END PGP PRIVATE KEY BLOCK-----`
+    });
+
+    const { data: decryptedData } = await openpgp.decrypt({
+      message: await openpgp.readMessage({ armoredMessage }),
+      decryptionKeys: privateKey
+    });
+    expect(decryptedData).to.equal('Testing\n');
+  });
+});
--- a/test/crypto/validate.js
+++ b/test/crypto/validate.js
@ -81,7 +81,7 @@ async function cloneKeyPacket(key) {
 }

 async function generatePrivateKeyObject(options) {
-  const config = { rejectCurves: new Set() };
+  const config = { rejectCurves: new Set(), ...options.config };
  const { privateKey } = await openpgp.generateKey({ ...options, userIDs: [{ name: 'Test', email: 'test@test.com' }], format: 'object', config });
  return privateKey;
 }
@ -314,6 +314,38 @@ export default () => {
    });
  });

+  describe('PQC parameter validation', function() {
+    let pqcEncryptionSubkey;
+    before(async () => {
+      const key = await generatePrivateKeyObject({ type: 'symmetric', subkeys: [{ type: 'pqc', config: { v6Keys: true } }] });
+      pqcEncryptionSubkey = key.subkeys[0];
+    });
+
+    async function cloneSubeyPacket(subkey) {
+      const subkeyPacket = new openpgp.SecretSubkeyPacket();
+      await subkeyPacket.read(subkey.keyPacket.write());
+      return subkeyPacket;
+    }
+
+    it('generated params are valid', async function() {
+      await expect(pqcEncryptionSubkey.keyPacket.validate()).to.not.be.rejected;
+    });
+
+    it('detect invalid ML-KEM public key part', async function() {
+      const keyPacket = await cloneSubeyPacket(pqcEncryptionSubkey);
+      const { mlkemPublicKey } = keyPacket.publicParams;
+      mlkemPublicKey[0]++;
+      await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
+    });
+
+    it('detect invalid ECC-KEM key part', async function() {
+      const keyPacket = await cloneSubeyPacket(pqcEncryptionSubkey);
+      const { eccPublicKey } = keyPacket.publicParams;
+      eccPublicKey[0]++;
+      await expect(keyPacket.validate()).to.be.rejectedWith('Key is invalid');
+    });
+  });
+
  describe('DSA parameter validation', function() {
    let dsaKey;
    before(async () => {
--- a/test/general/key.js
+++ b/test/general/key.js
@ -4607,6 +4607,17 @@ I8kWVkXU6vFOi+HWvv/ira7ofJu16NnoUkhclkUrk0mXubZvyl4GBg==
      expect(v6Key.subkeys).to.have.length(1);
    });

+    it('should throw when trying to add a ML-KEM PQC key to a v4 key', async function() {
+      const v4Key = await openpgp.decryptKey({
+        privateKey: await openpgp.readKey({ armoredKey: priv_key_rsa }),
+        passphrase: 'hello world'
+      });
+      expect(v4Key.keyPacket.version).to.equal(4);
+      expect(v4Key.subkeys).to.have.length(1);
+      await expect(v4Key.addSubkey({ type: 'pqc', sign: false })).to.be.rejectedWith(/Cannot generate v4 keys of type 'pqc'/);
+      expect(v4Key.subkeys).to.have.length(1);
+    });
+
    it('should throw when trying to encrypt a subkey separately from key', async function() {
      const privateKey = await openpgp.decryptKey({
        privateKey: await openpgp.readKey({ armoredKey: priv_key_rsa }),