// 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_ENCRYPTER_H_
#define NET_QUIC_CRYPTO_QUIC_ENCRYPTER_H_
#include "net/base/net_export.h"
#include "net/quic/quic_protocol.h"
namespace net {
class NET_EXPORT_PRIVATE QuicEncrypter {
public:
virtual ~QuicEncrypter() {}
static QuicEncrypter* 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;
// Encrypt encrypts |plaintext| and writes the ciphertext, plus a MAC over
// both |associated_data| and |plaintext| to |output|, using |nonce| as the
// nonce. |nonce| must be |8+GetNoncePrefixSize()| bytes long and |output|
// must point to a buffer that is at least
// |GetCiphertextSize(plaintext.size()| bytes long.
virtual bool Encrypt(base::StringPiece nonce,
base::StringPiece associated_data,
base::StringPiece plaintext,
unsigned char* output) = 0;
// Returns a newly created QuicData object containing the encrypted
// |plaintext| as well as a MAC over both |plaintext| and |associated_data|,
// or NULL if there is an error. |sequence_number| is appended to the
// |nonce_prefix| value provided in SetNoncePrefix() to form the nonce.
virtual QuicData* EncryptPacket(QuicPacketSequenceNumber sequence_number,
base::StringPiece associated_data,
base::StringPiece plaintext) = 0;
// GetKeySize() and GetNoncePrefixSize() tell the HKDF class how many bytes
// of key material needs to be derived from the master secret.
// NOTE: the sizes returned by GetKeySize() and GetNoncePrefixSize() are
// also correct for the QuicDecrypter of the same algorithm. So only
// QuicEncrypter has these two methods.
// Returns the size in bytes of a key for the algorithm.
virtual size_t GetKeySize() const = 0;
// Returns the size in bytes of the fixed initial part of the nonce.
virtual size_t GetNoncePrefixSize() const = 0;
// Returns the maximum length of plaintext that can be encrypted
// to ciphertext no larger than |ciphertext_size|.
virtual size_t GetMaxPlaintextSize(size_t ciphertext_size) const = 0;
// Returns the length of the ciphertext that would be generated by encrypting
// to plaintext of size |plaintext_size|.
virtual size_t GetCiphertextSize(size_t plaintext_size) const = 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_ENCRYPTER_H_