net/quic/crypto/null_encrypter.cc

// 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.

#include "net/quic/crypto/null_encrypter.h"
#include "net/quic/quic_data_writer.h"
#include "net/quic/quic_utils.h"

using base::StringPiece;
using std::string;

namespace net {

const size_t kHashSize = 16;  // size of uint128 serialized
const size_t kHashSizeShort = 12;  // size of uint128 serialized short

NullEncrypter::NullEncrypter(bool use_short_hash)
    : use_short_hash_(use_short_hash) {}

bool NullEncrypter::SetKey(StringPiece key) { return key.empty(); }

bool NullEncrypter::SetNoncePrefix(StringPiece nonce_prefix) {
  return nonce_prefix.empty();
}

bool NullEncrypter::Encrypt(
    StringPiece /*nonce*/,
    StringPiece associated_data,
    StringPiece plaintext,
    unsigned char* output) {
  string buffer = associated_data.as_string();
  plaintext.AppendToString(&buffer);
  uint128 hash = QuicUtils::FNV1a_128_Hash(buffer.data(), buffer.length());
  if (use_short_hash_) {
    QuicUtils::SerializeUint128Short(hash, output);
  } else {
    QuicUtils::SerializeUint128(hash, output);
  }
  memcpy(output + GetHashLength(), plaintext.data(), plaintext.size());
  return true;
}

QuicData* NullEncrypter::EncryptPacket(
    QuicPacketSequenceNumber /*sequence_number*/,
    StringPiece associated_data,
    StringPiece plaintext) {
  const size_t len = plaintext.size() + GetHashLength();
  uint8* buffer = new uint8[len];
  Encrypt(StringPiece(), associated_data, plaintext, buffer);
  return new QuicData(reinterpret_cast<char*>(buffer), len, true);
}

size_t NullEncrypter::GetKeySize() const { return 0; }

size_t NullEncrypter::GetNoncePrefixSize() const { return 0; }

size_t NullEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
  return ciphertext_size - GetHashLength();
}

size_t NullEncrypter::GetCiphertextSize(size_t plaintext_size) const {
  return plaintext_size + GetHashLength();
}

StringPiece NullEncrypter::GetKey() const { return StringPiece(); }

StringPiece NullEncrypter::GetNoncePrefix() const { return StringPiece(); }

size_t NullEncrypter::GetHashLength() const {
  return (use_short_hash_ ? kHashSizeShort : kHashSize);
}

}  // namespace net