fix: Drop recipientCertificate parameter from SessionEnvelopedData.de…

…crypt()

src/integration_tests/channelSession.test.ts

@@ -60,10 +60,7 @@ test('Encryption and decryption with subsequent DH keys', async () => {
   // Run 1: Alice initiates contact with Bob. Bob decrypts message.
   const plaintext1 = bufferToArray(Buffer.from('Hi. My name is Alice.'));
   const encryptionResult1 = await SessionEnvelopedData.encrypt(plaintext1, bobDhCertificate);
-  const decryptedPlaintext1 = await encryptionResult1.envelopedData.decrypt(
-    bobKeyPair1.privateKey,
-    bobDhCertificate,
-  );
+  const decryptedPlaintext1 = await encryptionResult1.envelopedData.decrypt(bobKeyPair1.privateKey);
   expectBuffersToEqual(decryptedPlaintext1, plaintext1);
   checkRecipientInfo(encryptionResult1.envelopedData, bobDhCertificate);
 
@@ -82,7 +79,6 @@ test('Encryption and decryption with subsequent DH keys', async () => {
   const encryptionResult2 = await SessionEnvelopedData.encrypt(plaintext2, aliceDhCert1);
   const decryptedPlaintext2 = await encryptionResult2.envelopedData.decrypt(
     encryptionResult1.dhPrivateKey as CryptoKey,
-    aliceDhCert1,
   );
   expectBuffersToEqual(decryptedPlaintext2, plaintext2);
   checkRecipientInfo(encryptionResult2.envelopedData, aliceDhCert1);
@@ -102,7 +98,6 @@ test('Encryption and decryption with subsequent DH keys', async () => {
   const encryptionResult3 = await SessionEnvelopedData.encrypt(plaintext3, bobDhCert2);
   const decryptedPlaintext3 = await encryptionResult3.envelopedData.decrypt(
     encryptionResult2.dhPrivateKey as CryptoKey,
-    bobDhCert2,
   );
   expectBuffersToEqual(decryptedPlaintext3, plaintext3);
   checkRecipientInfo(encryptionResult3.envelopedData, bobDhCert2);

src/lib/crypto_wrappers/cms/envelopedData.spec.ts

@@ -446,18 +446,11 @@ describe('SessionEnvelopedData', () => {
   describe('decrypt', () => {
     test('Decryption with the wrong private key should fail', async () => {
       const differentDhKeyPair = await generateECDHKeyPair();
-      const differentCertificate = await issueInitialDHKeyCertificate({
-        dhPublicKey: differentDhKeyPair.publicKey,
-        nodeCertificate,
-        nodePrivateKey,
-        serialNumber: 3,
-        validityEndDate: TOMORROW,
-      });
       const { envelopedData } = await SessionEnvelopedData.encrypt(plaintext, bobDhCertificate);
 
       expect.hasAssertions();
       try {
-        await envelopedData.decrypt(differentDhKeyPair.privateKey, differentCertificate);
+        await envelopedData.decrypt(differentDhKeyPair.privateKey);
       } catch (error) {
         expect(error).toBeInstanceOf(CMSError);
         expect(error.message).toStartWith(`Decryption failed: ${error.cause().message}`);
@@ -467,21 +460,39 @@ describe('SessionEnvelopedData', () => {
     test('Decryption should succeed with the right private key', async () => {
       const { envelopedData } = await SessionEnvelopedData.encrypt(plaintext, bobDhCertificate);
 
-      const decryptedPlaintext = await envelopedData.decrypt(bobDhPrivateKey, bobDhCertificate);
+      const decryptedPlaintext = await envelopedData.decrypt(bobDhPrivateKey);
       expectBuffersToEqual(decryptedPlaintext, plaintext);
     });
 
-    test('Recipient DH public key should be used to calculate shared secret', async () => {
+    test('Recipient DH certificate should be faked to set the key algorithm', async () => {
       const { envelopedData } = await SessionEnvelopedData.encrypt(plaintext, bobDhCertificate);
 
       jest.spyOn(pkijs.EnvelopedData.prototype, 'decrypt');
-      await envelopedData.decrypt(bobDhPrivateKey, bobDhCertificate);
+      await envelopedData.decrypt(bobDhPrivateKey);
 
       const pkijsDecryptCall = getMockContext(pkijs.EnvelopedData.prototype.decrypt).calls[0];
       const pkijsDecryptCallArgs = pkijsDecryptCall[1];
-      expect(pkijsDecryptCallArgs).toHaveProperty(
-        'recipientCertificate',
-        bobDhCertificate.pkijsCertificate,
+      expect(
+        pkijsDecryptCallArgs.recipientCertificate.subjectPublicKeyInfo.algorithm.algorithmParams.valueBlock.toString(),
+      ).toEqual(
+        bobDhCertificate.pkijsCertificate.subjectPublicKeyInfo.algorithm.algorithmParams.valueBlock.toString(),
+      );
+    });
+
+    test('Decryption with mismatching key algorithms should fail', async () => {
+      // This is a safeguard for the workaround to avoid having to pass the recipientCertificate
+      // to PKI.js EnvelopedData.encrypt().
+      const { privateKey } = await generateECDHKeyPair('P-384');
+      expect((privateKey.algorithm as EcKeyAlgorithm).namedCurve).not.toEqual(
+        (bobDhPrivateKey.algorithm as EcKeyAlgorithm).namedCurve,
+      );
+      const { envelopedData } = await SessionEnvelopedData.encrypt(plaintext, bobDhCertificate);
+
+      await expectPromiseToReject(
+        envelopedData.decrypt(privateKey),
+        // Leaving the typos unchanged because they come from a dependency of PKI.js and I
+        // want to make sure this scenario fails for the expected reason.
+        new CMSError('Decryption failed: Named corves of EC keys are not equals'),
       );
     });
   });

src/lib/crypto_wrappers/cms/envelopedData.ts

@@ -75,6 +75,8 @@ export abstract class EnvelopedData {
     });
     return contentInfo.toSchema().toBER(false);
   }
+
+  public abstract async decrypt(privateKey: CryptoKey): Promise<ArrayBuffer>;
 }
 
 /**
@@ -174,15 +176,20 @@ export class SessionEnvelopedData extends EnvelopedData {
     return convertAsn1IntegerToNumber(recipientCertificate.serialNumber);
   }
 
-  public async decrypt(
-    privateKey: CryptoKey,
-    dhRecipientCertificate: Certificate,
-  ): Promise<ArrayBuffer> {
-    return pkijsDecrypt(
-      this.pkijsEnvelopedData,
-      privateKey,
-      dhRecipientCertificate.pkijsCertificate,
-    );
+  public async decrypt(dhPrivateKey: CryptoKey): Promise<ArrayBuffer> {
+    // PKI.js requires the entire recipient's **certificate** to decrypt, but the only thing it
+    // uses it for is to get the public key algorithm. Which you can get from the private key.
+    const recipientCertificate = this.pkijsEnvelopedData.recipientInfos[0].value
+      .recipientCertificate;
+    const dhCertificate: pkijs.Certificate = {
+      subjectPublicKeyInfo: {
+        // @ts-ignore
+        algorithm: {
+          algorithmParams: recipientCertificate.subjectPublicKeyInfo.algorithm.algorithmParams,
+        },
+      },
+    };
+    return pkijsDecrypt(this.pkijsEnvelopedData, dhPrivateKey, dhCertificate);
   }
 }