shaka-packager/media/base/aes_encryptor.h

106 lines
3.2 KiB
C++

// Copyright (c) 2013 Google Inc. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//
// AES Encryptor implementation using openssl.
#ifndef MEDIA_BASE_AES_ENCRYPTOR_H_
#define MEDIA_BASE_AES_ENCRYPTOR_H_
#include <string>
#include <vector>
#include "base/memory/scoped_ptr.h"
struct aes_key_st;
typedef struct aes_key_st AES_KEY;
namespace media {
class AesCtrEncryptor {
public:
AesCtrEncryptor();
~AesCtrEncryptor();
// Initialize the encryptor with specified key. A random iv will be generated.
// |key| size should be 16. |iv_size| should be either 8 or 16.
// |block_offset_| is set to 0.
bool InitializeWithRandomIv(const std::vector<uint8>& key, uint8 iv_size);
// Initialize the encryptor with specified key and iv.
// |key| size should be 16. |iv| size should be either 8 or 16.
// |block_offset_| is set to 0.
bool InitializeWithIv(const std::vector<uint8>& key,
const std::vector<uint8>& iv);
// Various forms of encrypt calls. |block_offset_| will be updated according
// to input plaintext size.
bool Encrypt(const uint8* plaintext,
size_t plaintext_size,
uint8* ciphertext);
bool Encrypt(const std::vector<uint8>& plaintext,
std::vector<uint8>* ciphertext) {
ciphertext->resize(plaintext.size());
return Encrypt(&plaintext[0], plaintext.size(), &(*ciphertext)[0]);
}
bool Encrypt(const std::string& plaintext, std::string* ciphertext) {
ciphertext->resize(plaintext.size());
return Encrypt(reinterpret_cast<const uint8*>(plaintext.data()),
plaintext.size(),
reinterpret_cast<uint8*>(&(*ciphertext)[0]));
}
// For AES CTR, encryption and decryption are identical.
bool Decrypt(const uint8* ciphertext,
size_t ciphertext_size,
uint8* plaintext) {
return Encrypt(ciphertext, ciphertext_size, plaintext);
}
bool Decrypt(const std::vector<uint8>& ciphertext,
std::vector<uint8>* plaintext) {
return Encrypt(ciphertext, plaintext);
}
bool Decrypt(const std::string& ciphertext, std::string* plaintext) {
return Encrypt(ciphertext, plaintext);
}
// Update IV for next sample. |block_offset_| is reset to 0.
// As recommended in ISO/IEC FDIS 23001-7: CENC spec,
// For 64-bit IV size, new_iv = old_iv + 1;
// For 128-bit IV size, new_iv = old_iv + previous_sample_block_count.
void UpdateIv();
// Set IV. |block_offset_| is reset to 0.
void SetIv(const std::vector<uint8>& iv);
const std::vector<uint8>& iv() const { return iv_; }
uint32 block_offset() const { return block_offset_; }
private:
// Initialization vector, with size 8 or 16.
std::vector<uint8> iv_;
// Current block offset.
uint32 block_offset_;
// Openssl AES_KEY.
scoped_ptr<AES_KEY> aes_key_;
// Current AES-CTR counter.
std::vector<uint8> counter_;
// Encrypted counter.
std::vector<uint8> encrypted_counter_;
// Keep track of whether the counter has overflowed.
bool counter_overflow_;
DISALLOW_COPY_AND_ASSIGN(AesCtrEncryptor);
};
// TODO(kqyang): implement AesCbcEncryptor.
} // namespace
#endif // MEDIA_BASE_AES_ENCRYPTOR_H_