Use HMAC SHA-256, since SHA-1 won't work inside the Windows sandbox.

remoting/protocol/channel_authenticator.cc

 // Copyright (c) 2011 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/protocol/channel_authenticator.h"
 
 #include "base/compiler_specific.h"
 #include "base/string_piece.h"
 #include "crypto/hmac.h"
 #include "net/base/io_buffer.h"
 #include "net/base/net_errors.h"
 #include "net/socket/ssl_client_socket.h"
 #include "net/socket/ssl_server_socket.h"
 #include "net/socket/stream_socket.h"
 
 namespace remoting {
 namespace protocol {
 
 namespace {
 
 // Labels for use when exporting the SSL master keys.
 const char kClientSslExporterLabel[] = "EXPORTER-remoting-channel-auth-client";
 
-// Size of the HMAC-SHA-1 authentication digest.
-const size_t kAuthDigestLength = 20;
+// Size of the HMAC-SHA-256 authentication digest.
+const size_t kAuthDigestLength = 32;
 
 // static
 bool GetAuthBytes(const std::string& shared_secret,
                   const std::string& key_material,
                   std::string* auth_bytes) {
   // Generate auth digest based on the keying material and shared secret.
-  crypto::HMAC response(crypto::HMAC::SHA1);
-  if (!response.Init(shared_secret)) {
+  crypto::HMAC response(crypto::HMAC::SHA256);
+  if (!response.Init(key_material)) {
     NOTREACHED() << "HMAC::Init failed";
     return false;
   }
   unsigned char out_bytes[kAuthDigestLength];
-  if (!response.Sign(key_material, out_bytes, kAuthDigestLength)) {
+  if (!response.Sign(shared_secret, out_bytes, kAuthDigestLength)) {
     NOTREACHED() << "HMAC::Sign failed";
     return false;
   }
 
   auth_bytes->assign(out_bytes, out_bytes + kAuthDigestLength);
   return true;
 }
 
 }  // namespace
 
@@ skipping 158 matching lines @@
   auth_write_buf_->DidConsume(result);
   if (auth_write_buf_->BytesRemaining() > 0)
     return true;
 
   done_callback_.Run(SUCCESS);
   return false;
 }
 
 }  // namespace protocol
 }  // namespace remoting