Add comments and tests for libsignal-protocol curve validation

libtextsecure/libsignal-protocol.js

@@ -23624,6 +23624,8 @@ var Internal = Internal || {};
 
             return res.buffer;
         },
+        // This returns `true` if verification fails and `false` if it succeeds,
+        // which may be surprising.
         verify: function(pubKey, message, sig) {
             // Get a pointer to their public key
             var publicKey_ptr = _allocate(new Uint8Array(pubKey));
@@ -23808,6 +23810,8 @@ Curve25519Worker.prototype = {
 
                 return curve25519.sign(privKey, message);
             },
+            // This returns `true` if verification fails and `false` if it succeeds,
+            // which may be surprising.
             Ed25519Verify: function(pubKey, msg, sig) {
                 pubKey = validatePubKeyFormat(pubKey);
 
@@ -24487,6 +24491,7 @@ SessionBuilder.prototype = {
           device.signedPreKey.signature
         );
       }).then(didVerificationFail => {
+        // Ed25519Verify returns `false` when verification succeeds and `true` if it fails.
         if (didVerificationFail) {
           throw new Error('Signature verification failed');
         }

libtextsecure/test/protocol_wrapper_test.js

@@ -3,29 +3,52 @@
 
 /* global libsignal, textsecure */
 
-describe('Protocol Wrapper', function thisNeeded() {
+describe('Protocol Wrapper', function protocolWrapperDescribe() {
   const store = textsecure.storage.protocol;
-  const identifier = '+5558675309';
+  const identifier = '+15559999999';
 
   this.timeout(5000);
 
-  before(done => {
+  before(async function thisNeeded() {
     localStorage.clear();
-    libsignal.KeyHelper.generateIdentityKeyPair()
-      .then(key => textsecure.storage.protocol.saveIdentity(identifier, key))
-      .then(() => {
-        done();
-      });
+    this.identityKeyPair = await libsignal.KeyHelper.generateIdentityKeyPair();
+    await textsecure.storage.protocol.saveIdentity(
+      identifier,
+      this.identityKeyPair.pubKey
+    );
   });
 
   describe('processPreKey', () => {
-    it('rejects if the identity key changes', () => {
+    beforeEach(function thisNeeded() {
       const address = new libsignal.SignalProtocolAddress(identifier, 1);
-      const builder = new libsignal.SessionBuilder(store, address);
-      return builder
+      this.builder = new libsignal.SessionBuilder(store, address);
+    });
+
+    it('can process prekeys', async function thisNeeded() {
+      const signedPreKey = await libsignal.KeyHelper.generateSignedPreKey(
+        this.identityKeyPair,
+        123
+      );
+
+      await this.builder.processPreKey({
+        identityKey: this.identityKeyPair.pubKey,
+        registrationId: 1,
+        preKey: {
+          keyId: 1,
+          publicKey: this.identityKeyPair.pubKey,
+        },
+        signedPreKey: {
+          keyId: 123,
+          publicKey: signedPreKey.keyPair.pubKey,
+          signature: signedPreKey.signature,
+        },
+      });
+    });
+
+    it('rejects if the identity key changes', function thisNeeded() {
+      return this.builder
         .processPreKey({
           identityKey: textsecure.crypto.getRandomBytes(33),
-          encodedNumber: address.toString(),
         })
         .then(() => {
           throw new Error('Allowed to overwrite identity key');
@@ -34,5 +57,52 @@ describe('Protocol Wrapper', function thisNeeded() {
           assert.strictEqual(e.message, 'Identity key changed');
         });
     });
+
+    it('rejects with a bad prekey signature', async function thisNeeded() {
+      const signedPreKey = await libsignal.KeyHelper.generateSignedPreKey(
+        this.identityKeyPair,
+        123
+      );
+      const bogusSignature = textsecure.crypto.getRandomBytes(64);
+
+      return this.builder
+        .processPreKey({
+          identityKey: this.identityKeyPair.pubKey,
+          signedPreKey: {
+            keyId: 123,
+            publicKey: signedPreKey.keyPair.pubKey,
+            signature: bogusSignature,
+          },
+        })
+        .then(() => {
+          throw new Error("Didn't reject an invalid signature");
+        })
+        .catch(e => {
+          assert.strictEqual(e.message, 'Signature verification failed');
+        });
+    });
+
+    it('rejects with a prekey signature for a different identity', async function thisNeeded() {
+      const bogusSignedPreKey = await libsignal.KeyHelper.generateSignedPreKey(
+        await libsignal.KeyHelper.generateIdentityKeyPair(),
+        123
+      );
+
+      return this.builder
+        .processPreKey({
+          identityKey: this.identityKeyPair.pubKey,
+          signedPreKey: {
+            keyId: 123,
+            publicKey: bogusSignedPreKey.keyPair.pubKey,
+            signature: bogusSignedPreKey.signature,
+          },
+        })
+        .then(() => {
+          throw new Error("Didn't reject an invalid signature");
+        })
+        .catch(e => {
+          assert.strictEqual(e.message, 'Signature verification failed');
+        });
+    });
   });
 });