Implement verify() for HMAC using NSS

content/renderer/webcrypto_impl_nss.cc

Index: content/renderer/webcrypto_impl_nss.cc
diff --git a/content/renderer/webcrypto_impl_nss.cc b/content/renderer/webcrypto_impl_nss.cc
index caf986fce44f168fe5c390239d27336919066188..2a9fcf47e754ee6ea4acc6c0fb2196319bf7e585 100644
--- a/content/renderer/webcrypto_impl_nss.cc
+++ b/content/renderer/webcrypto_impl_nss.cc
@@ -6,10 +6,12 @@
 
 #include <pk11pub.h>
 #include <sechash.h>
+#include <vector>

[Ryan Sleevi, 2013/09/26 00:44:55]

there should be a linebreak here between C and C++ system headers.

[Bryan Eyler, 2013/09/26 02:17:44]

Done.

 
 #include "base/logging.h"
 #include "crypto/nss_util.h"
 #include "crypto/scoped_nss_types.h"
+#include "crypto/secure_util.h"
 #include "third_party/WebKit/public/platform/WebArrayBuffer.h"
 #include "third_party/WebKit/public/platform/WebCryptoAlgorithm.h"
 #include "third_party/WebKit/public/platform/WebCryptoAlgorithmParams.h"
@@ -249,4 +251,36 @@ bool WebCryptoImpl::SignInternal(
   return true;
 }
 
+bool WebCryptoImpl::VerifySignatureInternal(
+    const WebKit::WebCryptoAlgorithm& algorithm,
+    const WebKit::WebCryptoKey& key,
+    const unsigned char* signature,
+    unsigned signature_size,
+    const unsigned char* data,
+    unsigned data_size,
+    bool* signature_match) {
+  switch (algorithm.id()) {
+    case WebKit::WebCryptoAlgorithmIdHmac: {
+      WebKit::WebArrayBuffer result;
+      if (!SignInternal(algorithm, key, data, data_size, &result)) {
+        return false;
+      }
+
+      // Handling of truncated signatures is underspecified in the WebCrypto
+      // spec, so here we fail verification if a truncated signature is being
+      // verified.
+      // See https://www.w3.org/Bugs/Public/show_bug.cgi?id=23097
+      *signature_match =
+          result.byteLength() == signature_size &&
+          crypto::SecureMemEqual(result.data(), signature, signature_size);
+
+      break;
+    }
+    default:
+      return false;
+  }
+
+  return true;

[Ryan Sleevi, 2013/09/26 00:44:55]

Shouldn't the default be return false as well, and instead specifically return
true on 276?

[Bryan Eyler, 2013/09/26 00:57:39]

In line with the style of the rest of this file, I've been early exiting on
failure and making getting to the end a success.  Should I make this change
anyway?

+}
+
 }  // namespace content