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