Plumbing SSLPrivateKey (//net)

net/ssl/ssl_private_key.h

 // Copyright 2015 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_SSL_SSL_PRIVATE_KEY_H_
 #define NET_SSL_SSL_PRIVATE_KEY_H_
 
 #include <stdint.h>
 
 #include <vector>
 
 #include "base/callback_forward.h"
 #include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
+#include "base/memory/ref_counted.h"
 #include "base/strings/string_piece.h"
 #include "net/base/net_errors.h"
 
 namespace net {
 
 // An interface for a private key for use with SSL client authentication.
-class SSLPrivateKey {
+class SSLPrivateKey : public base::RefCountedThreadSafe<SSLPrivateKey> {
  public:
   using SignCallback = base::Callback<void(Error, const std::vector<uint8_t>&)>;
 
   enum class Type {
     RSA,
     ECDSA,
   };
 
   enum class Hash {
     MD5_SHA1,
     SHA1,
     SHA256,
     SHA384,
     SHA512,
   };
 
   SSLPrivateKey() {}
-  virtual ~SSLPrivateKey() {}
 
   // Returns whether the key is an RSA key or an ECDSA key. Although the signing
   // interface is type-agnositic and type tags in interfaces are discouraged,
   // TLS has key-specific logic in selecting which hashes to sign. Exposing the
   // key type avoids replicating BoringSSL's TLS-specific logic in SSLPrivateKey
   // implementations and complicating the interface between Chromium and
   // BoringSSL.
   virtual Type GetType() = 0;
 
   // Returns the digests that are supported by the key in decreasing preference.
   virtual std::vector<SSLPrivateKey::Hash> GetDigestPreferences() = 0;
 
   // Returns the maximum size of a signature, in bytes. For an RSA key, this
   // must be the size of the modulus.
   virtual size_t GetMaxSignatureLengthInBytes() = 0;
 
   // Asynchronously signs an |input| which was computed with the hash |hash|. On
   // completion, it calls |callback| with the signature or an error code if the
   // operation failed. For an RSA key, the signature is a PKCS#1 signature. The
   // SSLPrivateKey implementation is responsible for prepending the DigestInfo
   // prefix and adding PKCS#1 padding.
   virtual void SignDigest(Hash hash,
                           const base::StringPiece& input,
                           const SignCallback& callback) = 0;
 
+ protected:
+  virtual ~SSLPrivateKey() {}
+
  private:
+  friend class base::RefCountedThreadSafe<SSLPrivateKey>;
   DISALLOW_COPY_AND_ASSIGN(SSLPrivateKey);
 };
 
 }  // namespace net
 
 #endif  // NET_SSL_SSL_PRIVATE_KEY_H_