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// 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_decrypter.h"
#include <stdint.h>
#include "net/quic/quic_utils.h"
#include "net/quic/quic_data_reader.h"
using base::StringPiece;
using std::string;
namespace net {
NullDecrypter::NullDecrypter() {}
bool NullDecrypter::SetKey(StringPiece key) { return key.empty(); }
bool NullDecrypter::SetNoncePrefix(StringPiece nonce_prefix) {
return nonce_prefix.empty();
}
bool NullDecrypter::DecryptPacket(QuicPacketNumber /*packet_number*/,
const StringPiece& associated_data,
const StringPiece& ciphertext,
char* output,
size_t* output_length,
size_t max_output_length) {
QuicDataReader reader(ciphertext.data(), ciphertext.length());
uint128 hash;
if (!ReadHash(&reader, &hash)) {
return false;
}
StringPiece plaintext = reader.ReadRemainingPayload();
if (plaintext.length() > max_output_length) {
LOG(DFATAL) << "Output buffer must be larger than the plaintext.";
return false;
}
if (hash != ComputeHash(associated_data, plaintext)) {
return false;
}
// Copy the plaintext to output.
memcpy(output, plaintext.data(), plaintext.length());
*output_length = plaintext.length();
return true;
}
StringPiece NullDecrypter::GetKey() const { return StringPiece(); }
StringPiece NullDecrypter::GetNoncePrefix() const { return StringPiece(); }
const char* NullDecrypter::cipher_name() const {
return "NULL";
}
uint32 NullDecrypter::cipher_id() const {
return 0;
}
bool NullDecrypter::ReadHash(QuicDataReader* reader, uint128* hash) {
uint64 lo;
uint32 hi;
if (!reader->ReadUInt64(&lo) ||
!reader->ReadUInt32(&hi)) {
return false;
}
*hash = hi;
*hash <<= 64;
*hash += lo;
return true;
}
uint128 NullDecrypter::ComputeHash(const StringPiece& data1,
const StringPiece& data2) const {
uint128 correct_hash = QuicUtils::FNV1a_128_Hash_Two(
data1.data(), data1.length(), data2.data(), data2.length());
uint128 mask(UINT64_C(0x0), UINT64_C(0xffffffff));
mask <<= 96;
correct_hash &= ~mask;
return correct_hash;
}
} // namespace net
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