Files
whitebox/crypto_utils/aes_ctr_encryptor.cc
Aaron Vaage 69ea909ff5 Multiple Renewal Keys and Logging
In this code update we add a test to ensure that the White-box API
implementation handle seeing multiple renewal keys correctly. Since
there should be no more than one renewal key in a license response, upon
seeing a second renewal key, the implementation should return a
WB_RESULT_INVALID_PARAMETER code.

Due to changes in how Chrome manages CHECKS and DCHECKS, this code has
been updated to use the new headers.
2020-08-21 17:18:28 -07:00

80 lines
2.3 KiB
C++

// Copyright 2020 Google LLC. All Rights Reserved.
#include "crypto_utils/aes_ctr_encryptor.h"
#include <cstddef>
#include <cstdint>
#include <vector>
#include "base/check.h"
#include "base/logging.h"
namespace widevine {
namespace {
constexpr size_t kAesBlockSize = 16;
// Increment an 8-byte counter by 1. Return true if overflowed.
bool Increment64(uint8_t* counter) {
DCHECK(counter);
for (int i = 7; i >= 0; --i) {
if (++counter[i] != 0)
return false;
}
return true;
}
} // namespace
bool AesCtrEncryptor::SetKey(const uint8_t* key, size_t key_size) {
DCHECK(key);
if (key_size != kAesBlockSize && key_size != kAesBlockSize * 2) {
LOG(WARNING) << "Incorrect key size " << key_size;
return false;
}
if (AES_set_encrypt_key(key, key_size * 8, &aes_key_) != 0) {
LOG(WARNING) << "Invalid AES key.";
return false;
}
aes_key_size_ = key_size;
return true;
}
bool AesCtrEncryptor::Encrypt(const uint8_t* iv,
size_t iv_size,
const uint8_t* input_data,
size_t input_data_size,
uint8_t* output_data) {
DCHECK(iv);
DCHECK(input_data);
DCHECK(output_data);
if (aes_key_size_ == 0) {
LOG(WARNING) << "This class has not been initialized.";
return false;
}
// IV is allowed to be either AES BLOCK size or half of it.
if (iv_size != kAesBlockSize && iv_size != kAesBlockSize / 2) {
LOG(WARNING) << "Invalid IV size " << iv_size;
return false;
}
std::vector<uint8_t> counter(iv, iv + iv_size);
counter.resize(kAesBlockSize);
std::vector<uint8_t> encrypted_counter(kAesBlockSize);
for (size_t i = 0; i < input_data_size; i += 16) {
AES_encrypt(counter.data(), encrypted_counter.data(), &aes_key_);
// As mentioned in ISO/IEC 23001-7:2016 CENC spec, of the 16 byte counter
// block, bytes 8 to 15 (i.e. the least significant bytes) are used as a
// simple 64 bit unsigned integer that is incremented by one for each
// subsequent block of sample data processed and is kept in network byte
// order.
Increment64(counter.data() + 8);
for (size_t j = 0; j < kAesBlockSize && i + j < input_data_size; j++)
output_data[i + j] = input_data[i + j] ^ encrypted_counter[j];
}
return true;
}
} // namespace widevine