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// Copyright (c) 2013 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/aead_base_decrypter.h"
#include <pk11pub.h>
#include "base/memory/scoped_ptr.h"
#include "crypto/scoped_nss_types.h"
#include "net/quic/quic_flags.h"
#include "net/quic/quic_utils.h"
using base::StringPiece;
namespace net {
AeadBaseDecrypter::AeadBaseDecrypter(CK_MECHANISM_TYPE aead_mechanism,
size_t key_size,
size_t auth_tag_size,
size_t nonce_prefix_size)
: aead_mechanism_(aead_mechanism),
key_size_(key_size),
auth_tag_size_(auth_tag_size),
nonce_prefix_size_(nonce_prefix_size) {
DCHECK_LE(key_size_, sizeof(key_));
DCHECK_LE(nonce_prefix_size_, sizeof(nonce_prefix_));
}
AeadBaseDecrypter::~AeadBaseDecrypter() {}
bool AeadBaseDecrypter::SetKey(StringPiece key) {
DCHECK_EQ(key.size(), key_size_);
if (key.size() != key_size_) {
return false;
}
memcpy(key_, key.data(), key.size());
return true;
}
bool AeadBaseDecrypter::SetNoncePrefix(StringPiece nonce_prefix) {
DCHECK_EQ(nonce_prefix.size(), nonce_prefix_size_);
if (nonce_prefix.size() != nonce_prefix_size_) {
return false;
}
memcpy(nonce_prefix_, nonce_prefix.data(), nonce_prefix.size());
return true;
}
bool AeadBaseDecrypter::DecryptPacket(QuicPathId path_id,
QuicPacketNumber packet_number,
StringPiece associated_data,
StringPiece ciphertext,
char* output,
size_t* output_length,
size_t max_output_length) {
if (ciphertext.length() < auth_tag_size_) {
return false;
}
uint8_t nonce[sizeof(nonce_prefix_) + sizeof(packet_number)];
const size_t nonce_size = nonce_prefix_size_ + sizeof(packet_number);
DCHECK_LE(nonce_size, sizeof(nonce));
memcpy(nonce, nonce_prefix_, nonce_prefix_size_);
uint64_t path_id_packet_number =
QuicUtils::PackPathIdAndPacketNumber(path_id, packet_number);
memcpy(nonce + nonce_prefix_size_, &path_id_packet_number,
sizeof(path_id_packet_number));
// NSS 3.14.x incorrectly requires an output buffer at least as long as
// the ciphertext (NSS bug
// https://bugzilla.mozilla.org/show_bug.cgi?id= 853674). Fortunately
// QuicDecrypter::Decrypt() specifies that |output| must be as long as
// |ciphertext| on entry.
size_t plaintext_size = ciphertext.length() - auth_tag_size_;
// Import key_ into NSS.
SECItem key_item;
key_item.type = siBuffer;
key_item.data = key_;
key_item.len = key_size_;
PK11SlotInfo* slot = PK11_GetInternalSlot();
// The exact value of the |origin| argument doesn't matter to NSS as long as
// it's not PK11_OriginFortezzaHack, so pass PK11_OriginUnwrap as a
// placeholder.
crypto::ScopedPK11SymKey aead_key(
PK11_ImportSymKey(slot, aead_mechanism_, PK11_OriginUnwrap, CKA_DECRYPT,
&key_item, nullptr));
PK11_FreeSlot(slot);
slot = nullptr;
if (!aead_key) {
DVLOG(1) << "PK11_ImportSymKey failed";
return false;
}
AeadParams aead_params = {0};
FillAeadParams(StringPiece(reinterpret_cast<char*>(nonce), nonce_size),
associated_data, auth_tag_size_, &aead_params);
SECItem param;
param.type = siBuffer;
param.data = reinterpret_cast<unsigned char*>(&aead_params.data);
param.len = aead_params.len;
unsigned int output_len;
if (PK11_Decrypt(aead_key.get(), aead_mechanism_, ¶m,
reinterpret_cast<uint8_t*>(output), &output_len,
max_output_length,
reinterpret_cast<const unsigned char*>(ciphertext.data()),
ciphertext.length()) != SECSuccess) {
return false;
}
if (output_len != plaintext_size) {
DVLOG(1) << "Wrong output length";
return false;
}
*output_length = output_len;
return true;
}
StringPiece AeadBaseDecrypter::GetKey() const {
return StringPiece(reinterpret_cast<const char*>(key_), key_size_);
}
StringPiece AeadBaseDecrypter::GetNoncePrefix() const {
if (nonce_prefix_size_ == 0) {
return StringPiece();
}
return StringPiece(reinterpret_cast<const char*>(nonce_prefix_),
nonce_prefix_size_);
}
} // namespace net
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