[Chromoting] Factor out common code for pin hashing.

remoting/host/pin_hash.cc

Index: remoting/host/pin_hash.cc
diff --git a/remoting/host/pin_hash.cc b/remoting/host/pin_hash.cc
new file mode 100644
index 0000000000000000000000000000000000000000..fe17f38caff4d46e4fd812462bb7b9788c94e317
--- /dev/null
+++ b/remoting/host/pin_hash.cc
@@ -0,0 +1,39 @@
+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "remoting/host/pin_hash.h"
+
+#include "base/base64.h"
+#include "base/logging.h"
+#include "remoting/protocol/authentication_method.h"
+#include "remoting/protocol/me2me_host_authenticator_factory.h"
+
+namespace remoting {
+
+std::string MakeHostPinHash(const std::string& host_id,
+                            const std::string& pin) {
+  std::string hash = protocol::AuthenticationMethod::ApplyHashFunction(
+      protocol::AuthenticationMethod::HMAC_SHA256, host_id, pin);
+  std::string hash_base64;
+  if (!base::Base64Encode(hash, &hash_base64)) {
+    LOG(FATAL) << "Base64Encode failed";
+  }
+  return "hmac:" + hash_base64;
+}
+
+bool VerifyHostPinHash(const std::string& hash,
+                       const std::string& host_id,
+                       const std::string& pin) {
+  remoting::protocol::SharedSecretHash hash_parsed;
+  if (!hash_parsed.Parse(hash)) {
+    LOG(FATAL) << "Invalid hash.";
+    return false;
+  }
+  std::string hash_calculated =
+      remoting::protocol::AuthenticationMethod::ApplyHashFunction(
+          hash_parsed.hash_function, host_id, pin);
+  return hash_calculated == hash_parsed.value;
+}
+
+}  // namespace remoting