136 lines
4.2 KiB
C++
136 lines
4.2 KiB
C++
// Copyright 2016 Google LLC. All rights reserved.
|
|
//
|
|
// Use of this source code is governed by a BSD-style
|
|
// license that can be found in the LICENSE file or at
|
|
// https://developers.google.com/open-source/licenses/bsd
|
|
|
|
#include "packager/media/base/aes_cryptor.h"
|
|
|
|
#include <openssl/aes.h>
|
|
#include <openssl/crypto.h>
|
|
#include <openssl/err.h>
|
|
#include <openssl/rand.h>
|
|
|
|
#include <string>
|
|
#include <vector>
|
|
|
|
#include "packager/base/logging.h"
|
|
|
|
namespace {
|
|
|
|
// According to ISO/IEC 23001-7:2016 CENC spec, IV should be either
|
|
// 64-bit (8-byte) or 128-bit (16-byte).
|
|
bool IsIvSizeValid(size_t iv_size) {
|
|
return iv_size == 8 || iv_size == 16;
|
|
}
|
|
|
|
} // namespace
|
|
|
|
namespace shaka {
|
|
namespace media {
|
|
|
|
AesCryptor::AesCryptor(ConstantIvFlag constant_iv_flag)
|
|
: aes_key_(new AES_KEY),
|
|
constant_iv_flag_(constant_iv_flag),
|
|
num_crypt_bytes_(0) {
|
|
CRYPTO_library_init();
|
|
}
|
|
|
|
AesCryptor::~AesCryptor() {}
|
|
|
|
bool AesCryptor::Crypt(const std::vector<uint8_t>& text,
|
|
std::vector<uint8_t>* crypt_text) {
|
|
// Save text size to make it work for in-place conversion, since the
|
|
// next statement will update the text size.
|
|
const size_t text_size = text.size();
|
|
crypt_text->resize(text_size + NumPaddingBytes(text_size));
|
|
size_t crypt_text_size = crypt_text->size();
|
|
if (!Crypt(text.data(), text_size, crypt_text->data(), &crypt_text_size)) {
|
|
return false;
|
|
}
|
|
DCHECK_LE(crypt_text_size, crypt_text->size());
|
|
crypt_text->resize(crypt_text_size);
|
|
return true;
|
|
}
|
|
|
|
bool AesCryptor::Crypt(const std::string& text, std::string* crypt_text) {
|
|
// Save text size to make it work for in-place conversion, since the
|
|
// next statement will update the text size.
|
|
const size_t text_size = text.size();
|
|
crypt_text->resize(text_size + NumPaddingBytes(text_size));
|
|
size_t crypt_text_size = crypt_text->size();
|
|
if (!Crypt(reinterpret_cast<const uint8_t*>(text.data()), text_size,
|
|
reinterpret_cast<uint8_t*>(&(*crypt_text)[0]), &crypt_text_size))
|
|
return false;
|
|
DCHECK_LE(crypt_text_size, crypt_text->size());
|
|
crypt_text->resize(crypt_text_size);
|
|
return true;
|
|
}
|
|
|
|
bool AesCryptor::SetIv(const std::vector<uint8_t>& iv) {
|
|
if (!IsIvSizeValid(iv.size())) {
|
|
LOG(ERROR) << "Invalid IV size: " << iv.size();
|
|
return false;
|
|
}
|
|
iv_ = iv;
|
|
num_crypt_bytes_ = 0;
|
|
SetIvInternal();
|
|
return true;
|
|
}
|
|
|
|
void AesCryptor::UpdateIv() {
|
|
if (constant_iv_flag_ == kUseConstantIv)
|
|
return;
|
|
|
|
uint64_t increment = 0;
|
|
// As recommended in ISO/IEC 23001-7:2016 CENC spec, for 64-bit (8-byte)
|
|
// IV_Sizes, initialization vectors for subsequent samples can be created by
|
|
// incrementing the initialization vector of the previous sample.
|
|
// For 128-bit (16-byte) IV_Sizes, initialization vectors for subsequent
|
|
// samples should be created by adding the block count of the previous sample
|
|
// to the initialization vector of the previous sample.
|
|
// There is no official recommendation of how IV for next sample should be
|
|
// generated for CBC mode. We use the same generation algorithm as CTR here.
|
|
if (iv_.size() == 8) {
|
|
increment = 1;
|
|
} else {
|
|
DCHECK_EQ(16u, iv_.size());
|
|
increment = (num_crypt_bytes_ + AES_BLOCK_SIZE - 1) / AES_BLOCK_SIZE;
|
|
}
|
|
|
|
for (int i = iv_.size() - 1; increment > 0 && i >= 0; --i) {
|
|
increment += iv_[i];
|
|
iv_[i] = increment & 0xFF;
|
|
increment >>= 8;
|
|
}
|
|
num_crypt_bytes_ = 0;
|
|
SetIvInternal();
|
|
}
|
|
|
|
bool AesCryptor::GenerateRandomIv(FourCC protection_scheme,
|
|
std::vector<uint8_t>* iv) {
|
|
// ISO/IEC 23001-7:2016 10.1 and 10.3 For 'cenc' and 'cens'
|
|
// default_Per_Sample_IV_Size and Per_Sample_IV_Size SHOULD be 8-bytes.
|
|
// There is no official guideline on the iv size for 'cbc1' and 'cbcs',
|
|
// but 16-byte provides better security.
|
|
const size_t iv_size =
|
|
(protection_scheme == FOURCC_cenc || protection_scheme == FOURCC_cens)
|
|
? 8
|
|
: 16;
|
|
iv->resize(iv_size);
|
|
if (RAND_bytes(iv->data(), iv_size) != 1) {
|
|
LOG(ERROR) << "RAND_bytes failed with error: "
|
|
<< ERR_error_string(ERR_get_error(), NULL);
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|
|
|
|
size_t AesCryptor::NumPaddingBytes(size_t size) const {
|
|
// No padding by default.
|
|
return 0;
|
|
}
|
|
|
|
} // namespace media
|
|
} // namespace shaka
|