117 lines
4.0 KiB
C++
117 lines
4.0 KiB
C++
// Copyright 2014 Google Inc. All rights reserved.
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//
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file or at
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// https://developers.google.com/open-source/licenses/bsd
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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 "packager/base/macros.h"
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#include "packager/base/memory/scoped_ptr.h"
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#include "packager/media/base/aes_cryptor.h"
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namespace edash_packager {
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namespace media {
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class AesEncryptor : public AesCryptor {
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public:
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/// @param constant_iv_flag indicates whether a constant iv is used,
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/// kUseConstantIv means that the same iv is used for all Crypt calls
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/// until iv is changed via SetIv; otherwise, iv can be incremented
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/// (for counter mode) or chained (for cipher block chaining mode)
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/// internally inside Crypt call, i.e. iv will be updated across Crypt
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/// calls.
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explicit AesEncryptor(ConstantIvFlag constant_iv_flag);
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~AesEncryptor() override;
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/// Initialize the encryptor with specified key and IV.
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/// @return true on successful initialization, false otherwise.
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bool InitializeWithIv(const std::vector<uint8_t>& key,
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const std::vector<uint8_t>& iv) override;
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private:
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DISALLOW_COPY_AND_ASSIGN(AesEncryptor);
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};
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// Class which implements AES-CTR counter-mode encryption.
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class AesCtrEncryptor : public AesEncryptor {
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public:
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AesCtrEncryptor();
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~AesCtrEncryptor() override;
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uint32_t block_offset() const { return block_offset_; }
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private:
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bool CryptInternal(const uint8_t* plaintext,
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size_t plaintext_size,
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uint8_t* ciphertext,
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size_t* ciphertext_size) override;
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void SetIvInternal() override;
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// Current block offset.
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uint32_t block_offset_;
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// Current AES-CTR counter.
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std::vector<uint8_t> counter_;
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// Encrypted counter.
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std::vector<uint8_t> encrypted_counter_;
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DISALLOW_COPY_AND_ASSIGN(AesCtrEncryptor);
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};
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enum CbcPaddingScheme {
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// Residual block is left unencrypted.
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kNoPadding,
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// Residual block is padded with pkcs5 and encrypted.
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kPkcs5Padding,
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// Residual block and the next-to-last block are encrypted using ciphertext
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// stealing method.
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kCtsPadding,
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};
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// Class which implements AES-CBC (Cipher block chaining) encryption.
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class AesCbcEncryptor : public AesEncryptor {
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public:
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/// Creates a AesCbcEncryptor with continous cipher block chain across Crypt
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/// calls, i.e. AesCbcEncryptor(padding_scheme, kDontUseConstantIv).
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/// @param padding_scheme indicates the padding scheme used. Currently
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/// supported schemes: kNoPadding, kPkcs5Padding, kCtsPadding.
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explicit AesCbcEncryptor(CbcPaddingScheme padding_scheme);
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/// @param padding_scheme indicates the padding scheme used. Currently
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/// supported schemes: kNoPadding, kPkcs5Padding, kCtsPadding.
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/// @param constant_iv_flag indicates whether a constant iv is used,
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/// kUseConstantIv means that the same iv is used for all Crypt calls
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/// until iv is changed via SetIv; otherwise, iv is updated internally
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/// and there is a continuous cipher block chain across Crypt calls
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/// util iv is changed explicitly via SetIv or UpdateIv functions.
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AesCbcEncryptor(CbcPaddingScheme padding_scheme,
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ConstantIvFlag constant_iv_flag);
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~AesCbcEncryptor() override;
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private:
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bool CryptInternal(const uint8_t* plaintext,
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size_t plaintext_size,
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uint8_t* ciphertext,
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size_t* ciphertext_size) override;
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void SetIvInternal() override;
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size_t NumPaddingBytes(size_t size) const override;
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const CbcPaddingScheme padding_scheme_;
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// 16-byte internal iv for crypto operations.
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std::vector<uint8_t> internal_iv_;
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DISALLOW_COPY_AND_ASSIGN(AesCbcEncryptor);
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};
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} // namespace media
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} // namespace edash_packager
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#endif // MEDIA_BASE_AES_ENCRYPTOR_H_
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