From 0ef51065166b63617f2bdfc3f54f2c1a6a4b9064 Mon Sep 17 00:00:00 2001
From: larabr <7375870+larabr@users.noreply.github.com>
Date: Fri, 15 Mar 2024 14:06:09 +0100
Subject: [PATCH] Add PQC KEM key validation

---
 src/crypto/crypto.js                          |  7 ++--
 .../public_key/post_quantum/kem/ecc_kem.js    |  9 ++++++
 .../public_key/post_quantum/kem/index.js      |  2 +-
 src/crypto/public_key/post_quantum/kem/kem.js |  7 ++++
 .../public_key/post_quantum/kem/ml_kem.js     | 14 ++++++++
 test/crypto/validate.js                       | 32 +++++++++++++++++++
 6 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/src/crypto/crypto.js b/src/crypto/crypto.js
index ba1a94255b..f8ded6aaee 100644
--- a/src/crypto/crypto.js
+++ b/src/crypto/crypto.js
@@ -569,8 +569,11 @@ export async function validateParams(algo, publicParams, privateParams) {
       return keySize === keyMaterial.length &&
         util.equalsUint8Array(digest, await hash.sha256(hashSeed));
     }
-    case enums.publicKey.pqc_mlkem_x25519:
-      throw new Error('TODO');
+    case enums.publicKey.pqc_mlkem_x25519: {
+      const { eccSecretKey, mlkemSecretKey } = privateParams;
+      const { eccPublicKey, mlkemPublicKey } = publicParams;
+      return publicKey.postQuantum.kem.validateParams(algo, eccPublicKey, eccSecretKey, mlkemPublicKey, mlkemSecretKey);
+    }
     default:
       throw new Error('Unknown public key algorithm.');
   }
diff --git a/src/crypto/public_key/post_quantum/kem/ecc_kem.js b/src/crypto/public_key/post_quantum/kem/ecc_kem.js
index 7d9878c206..7c016ecea0 100644
--- a/src/crypto/public_key/post_quantum/kem/ecc_kem.js
+++ b/src/crypto/public_key/post_quantum/kem/ecc_kem.js
@@ -52,3 +52,12 @@ export async function decaps(algo, eccCipherText, eccSecretKey, eccPublicKey) {
       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');
+  }
+}
diff --git a/src/crypto/public_key/post_quantum/kem/index.js b/src/crypto/public_key/post_quantum/kem/index.js
index 298832a4f3..0a2da99b41 100644
--- a/src/crypto/public_key/post_quantum/kem/index.js
+++ b/src/crypto/public_key/post_quantum/kem/index.js
@@ -1 +1 @@
-export { generate, encrypt, decrypt } from './kem';
+export { generate, encrypt, decrypt, validateParams } from './kem';
diff --git a/src/crypto/public_key/post_quantum/kem/kem.js b/src/crypto/public_key/post_quantum/kem/kem.js
index 6fec55df32..3ee2d56260 100644
--- a/src/crypto/public_key/post_quantum/kem/kem.js
+++ b/src/crypto/public_key/post_quantum/kem/kem.js
@@ -71,3 +71,10 @@ async function multiKeyCombine(eccKeyShare, eccCipherText, mlkemKeyShare, mlkemC
 
   return mb;
 }
+
+export async function validateParams(algo, eccPublicKey, eccSecretKey, mlkemPublicKey, mlkemSecretKey) {
+  const eccValidationPromise = eccKem.validateParams(algo, eccPublicKey, eccSecretKey);
+  const mlkemValidationPromise = mlKem.validateParams(algo, mlkemPublicKey, mlkemSecretKey);
+  const valid = await eccValidationPromise && await mlkemValidationPromise;
+  return valid;
+}
diff --git a/src/crypto/public_key/post_quantum/kem/ml_kem.js b/src/crypto/public_key/post_quantum/kem/ml_kem.js
index a51d2fbf12..12d62539f8 100644
--- a/src/crypto/public_key/post_quantum/kem/ml_kem.js
+++ b/src/crypto/public_key/post_quantum/kem/ml_kem.js
@@ -1,4 +1,5 @@
 import enums from '../../../../enums';
+import util from '../../../../util';
 
 export async function generate(algo) {
   switch (algo) {
@@ -41,3 +42,16 @@ export async function decaps(algo, mlkemCipherText, mlkemSecretKey) {
       throw new Error('Unsupported KEM algorithm');
   }
 }
+
+export async function validateParams(algo, mlkemPublicKey, mlkemSecretKey) {
+  switch (algo) {
+    case enums.publicKey.pqc_mlkem_x25519: {
+      // TODO confirm this is the best option performance- & security-wise (is key re-generation faster?)
+      const { mlkemCipherText: validationCipherText, mlkemKeyShare: validationKeyShare } = await encaps(algo, mlkemPublicKey);
+      const resultingKeyShare = await decaps(algo, validationCipherText, mlkemSecretKey);
+      return util.equalsUint8Array(resultingKeyShare, validationKeyShare);
+    }
+    default:
+      throw new Error('Unsupported KEM algorithm');
+  }
+}
diff --git a/test/crypto/validate.js b/test/crypto/validate.js
index 8ed63089c8..fde15d3eaf 100644
--- a/test/crypto/validate.js
+++ b/test/crypto/validate.js
@@ -314,6 +314,38 @@ export default () => {
     });
   });
 
+  describe('PQC parameter validation', function() {
+    let pqcEncryptionSubkey;
+    before(async () => {
+      const key = await generatePrivateKeyObject({ type: 'symmetric', subkeys: [{ type: 'pqc' }] });
+      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 () => {