// 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_QUIC_CRYPTO_QUIC_DECRYPTER_H_
#define NET_QUIC_CRYPTO_QUIC_DECRYPTER_H_
#include "net/base/net_export.h"
#include "net/quic/quic_protocol.h"
namespace net {
class NET_EXPORT_PRIVATE QuicDecrypter {
public:
virtual ~QuicDecrypter() {}
static QuicDecrypter* Create(QuicTag algorithm);
// Sets the encryption key. Returns true on success, false on failure.
//
// NOTE: The key is the client_write_key or server_write_key derived from
// the master secret.
virtual bool SetKey(base::StringPiece key) = 0;
// Sets the fixed initial bytes of the nonce. Returns true on success,
// false on failure.
//
// NOTE: The nonce prefix is the client_write_iv or server_write_iv
// derived from the master secret. A 64-bit packet sequence number will
// be appended to form the nonce.
//
// <------------ 64 bits ----------->
// +---------------------+----------------------------------+
// | Fixed prefix | Packet sequence number |
// +---------------------+----------------------------------+
// Nonce format
//
// The security of the nonce format requires that QUIC never reuse a
// packet sequence number, even when retransmitting a lost packet.
virtual bool SetNoncePrefix(base::StringPiece nonce_prefix) = 0;
// Decrypt authenticates |associated_data| and |ciphertext| and then decrypts
// |ciphertext| into |output|, using |nonce|. |nonce| must be 8 bytes longer
// than the nonce prefix length returned by GetNoncePrefixSize() (of the
// encrypter). |output| must be as long as |ciphertext| on entry and, on
// successful return, the true length of the plaintext will be written to
// |*output_length|.
virtual bool Decrypt(base::StringPiece nonce,
base::StringPiece associated_data,
base::StringPiece ciphertext,
unsigned char* output,
size_t* output_length) = 0;
// Returns a newly created QuicData object containing the decrypted
// |ciphertext| or NULL if there is an error. |sequence_number| is
// appended to the |nonce_prefix| value provided in SetNoncePrefix()
// to form the nonce.
// TODO(wtc): add a way for DecryptPacket to report decryption failure due
// to non-authentic inputs, as opposed to other reasons for failure.
virtual QuicData* DecryptPacket(QuicPacketSequenceNumber sequence_number,
base::StringPiece associated_data,
base::StringPiece ciphertext) = 0;
// For use by unit tests only.
virtual base::StringPiece GetKey() const = 0;
virtual base::StringPiece GetNoncePrefix() const = 0;
};
} // namespace net
#endif // NET_QUIC_CRYPTO_QUIC_DECRYPTER_H_