net: disable ECDSA ciphersuites on platforms where we can't support it.

net/base/ssl_config_service.h

 // 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.
 
 #ifndef NET_BASE_SSL_CONFIG_SERVICE_H_
 #define NET_BASE_SSL_CONFIG_SERVICE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 56 matching lines @@
   // Presorted list of cipher suites which should be explicitly prevented from
   // being used in addition to those disabled by the net built-in policy.
   //
   // By default, all cipher suites supported by the underlying SSL
   // implementation will be enabled except for:
   // - Null encryption cipher suites.
   // - Weak cipher suites: < 80 bits of security strength.
   // - FORTEZZA cipher suites (obsolete).
   // - IDEA cipher suites (RFC 5469 explains why).
   // - Anonymous cipher suites.
+  // - ECDSA cipher suites on platforms that do not support ECDSA signed
+  //   certificates, as servers may use the presence of such ciphersuites as a
+  //   hint to send an ECDSA certificate.
   // The ciphers listed in |disabled_cipher_suites| will be removed in addition
   // to the above list.
   //
   // Though cipher suites are sent in TLS as "uint8 CipherSuite[2]", in
   // big-endian form, they should be declared in host byte order, with the
   // first uint8 occupying the most significant byte.
   // Ex: To disable TLS_RSA_WITH_RC4_128_MD5, specify 0x0004, while to
   // disable TLS_ECDH_ECDSA_WITH_RC4_128_SHA, specify 0xC002.
   //
   // Note: Not implemented when using Schannel/SSLClientSocketWin.
@@ skipping 114 matching lines @@
   void ProcessConfigUpdate(const SSLConfig& orig_config,
                            const SSLConfig& new_config);
 
  private:
   ObserverList<Observer> observer_list_;
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_SSL_CONFIG_SERVICE_H_