Renaming header.alg mismatch exception to invalid algorithm and adding more mismatch tests.

index.js

@@ -126,7 +126,7 @@ module.exports.verify = function(jwtString, secretOrPublicKey, options, callback
   var header = decodedToken.header;
 
   if (!~options.algorithms.indexOf(header.alg)) {
-    return done(new JsonWebTokenError('invalid signature'));
+    return done(new JsonWebTokenError('invalid algorithm'));
   }
 
   var valid;

test/wrong_alg.tests.js

@@ -11,10 +11,32 @@ var pub = fs.readFileSync(path.join(__dirname, 'pub.pem'), 'utf8');
 
 var TOKEN = 'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJmb28iOiJiYXIiLCJpYXQiOjE0MjY1NDY5MTl9.ETgkTn8BaxIX4YqvUWVFPmum3moNZ7oARZtSBXb_vP4';
 
-describe('signing with pub key as symmetric', function () {
-  it('should not verify', function () {
-    expect(function () {
-      jwt.verify(TOKEN, pub);
-    }).to.throw(JsonWebTokenError, /invalid signature/);
+describe('when setting a wrong `header.alg`', function () {
+
+  describe('signing with pub key as symmetric', function () {
+    it('should not verify', function () {
+      expect(function () {
+        jwt.verify(TOKEN, pub);
+      }).to.throw(JsonWebTokenError, /invalid algorithm/);
+    });
   });
-});
+
+  describe('signing with pub key as HS256 and whitelisting only RS256', function () {
+    it('should not verify', function () {
+      expect(function () {
+        jwt.verify(TOKEN, pub, {algorithms: ['RS256']});
+      }).to.throw(JsonWebTokenError, /invalid algorithm/);
+    });
+  });
+
+  describe('signing with HS256 and checking with HS384', function () {
+    it('should not verify', function () {
+      expect(function () {
+        var token = jwt.sign({foo: 'bar'}, 'secret', {algorithm: 'HS256'});
+        jwt.verify(token, 'some secret', {algorithms: ['HS384']});
+      }).to.throw(JsonWebTokenError, /invalid algorithm/);
+    });
+  });
+
+
+});