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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_encrypter.h"
#include <pk11pub.h>
#include "base/memory/scoped_ptr.h"
#include "crypto/scoped_nss_types.h"
using base::StringPiece;
namespace net {
AeadBaseEncrypter::AeadBaseEncrypter(CK_MECHANISM_TYPE aead_mechanism,
PK11_EncryptFunction pk11_encrypt,
size_t key_size,
size_t auth_tag_size,
size_t nonce_prefix_size)
: aead_mechanism_(aead_mechanism),
pk11_encrypt_(pk11_encrypt),
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_));
}
AeadBaseEncrypter::~AeadBaseEncrypter() {}
bool AeadBaseEncrypter::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 AeadBaseEncrypter::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 AeadBaseEncrypter::Encrypt(StringPiece nonce,
StringPiece associated_data,
StringPiece plaintext,
unsigned char* output) {
if (nonce.size() != nonce_prefix_size_ + sizeof(QuicPacketSequenceNumber)) {
return false;
}
size_t ciphertext_size = GetCiphertextSize(plaintext.length());
// Import key_ into NSS.
SECItem key_item;
key_item.type = siBuffer;
key_item.data = key_;
key_item.len = key_size_;
PK11SlotInfo* slot = PK11_GetInternalSlot();
// TODO(wtc): For an AES-GCM key, the correct value for |key_mechanism| is
// CKM_AES_GCM, but because of NSS bug
// https://bugzilla.mozilla.org/show_bug.cgi?id=853285, use CKM_AES_ECB as a
// workaround. Remove this when we require NSS 3.15.
CK_MECHANISM_TYPE key_mechanism = aead_mechanism_;
if (key_mechanism == CKM_AES_GCM) {
key_mechanism = CKM_AES_ECB;
}
// The exact value of the |origin| argument doesn't matter to NSS as long as
// it's not PK11_OriginFortezzaHack, so we pass PK11_OriginUnwrap as a
// placeholder.
crypto::ScopedPK11SymKey aead_key(PK11_ImportSymKey(
slot, key_mechanism, PK11_OriginUnwrap, CKA_ENCRYPT, &key_item, nullptr));
PK11_FreeSlot(slot);
slot = nullptr;
if (!aead_key) {
DVLOG(1) << "PK11_ImportSymKey failed";
return false;
}
AeadParams aead_params = {0};
FillAeadParams(nonce, 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_encrypt_(aead_key.get(), aead_mechanism_, ¶m,
output, &output_len, ciphertext_size,
reinterpret_cast<const unsigned char*>(plaintext.data()),
plaintext.size()) != SECSuccess) {
DVLOG(1) << "pk11_encrypt_ failed";
return false;
}
if (output_len != ciphertext_size) {
DVLOG(1) << "Wrong output length";
return false;
}
return true;
}
bool AeadBaseEncrypter::EncryptPacket(QuicPacketSequenceNumber sequence_number,
StringPiece associated_data,
StringPiece plaintext,
char* output,
size_t* output_length,
size_t max_output_length) {
size_t ciphertext_size = GetCiphertextSize(plaintext.length());
if (max_output_length < ciphertext_size) {
return false;
}
// TODO(ianswett): Introduce a check to ensure that we don't encrypt with the
// same sequence number twice.
const size_t nonce_size = nonce_prefix_size_ + sizeof(sequence_number);
memcpy(output, nonce_prefix_, nonce_prefix_size_);
memcpy(output + nonce_prefix_size_, &sequence_number,
sizeof(sequence_number));
if (!Encrypt(StringPiece(output, nonce_size), associated_data, plaintext,
reinterpret_cast<unsigned char*>(output))) {
return false;
}
*output_length = ciphertext_size;
return true;
}
size_t AeadBaseEncrypter::GetKeySize() const { return key_size_; }
size_t AeadBaseEncrypter::GetNoncePrefixSize() const {
return nonce_prefix_size_;
}
size_t AeadBaseEncrypter::GetMaxPlaintextSize(size_t ciphertext_size) const {
return ciphertext_size - auth_tag_size_;
}
size_t AeadBaseEncrypter::GetCiphertextSize(size_t plaintext_size) const {
return plaintext_size + auth_tag_size_;
}
StringPiece AeadBaseEncrypter::GetKey() const {
return StringPiece(reinterpret_cast<const char*>(key_), key_size_);
}
StringPiece AeadBaseEncrypter::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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