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/* Copyright 2015 OpenMarket Ltd
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#ifndef AXOLOTL_CIPHER_HH_
#define AXOLOTL_CIPHER_HH_
#include <cstdint>
namespace axolotl {
class Cipher {
public:
virtual ~Cipher();
/**
* Returns the length of the message authentication code that will be
* appended to the output.
*/
virtual std::size_t mac_length() const = 0;
/**
* Returns the length of cipher-text for a given length of plain-text.
*/
virtual std::size_t encrypt_ciphertext_length(
std::size_t plaintext_length
) const = 0;
/*
* Encrypts the plain-text into the output buffer and authenticates the
* contents of the output buffer covering both cipher-text and any other
* associated data in the output buffer.
*
* |---------------------------------------output_length-->|
* output |--ciphertext_length-->| |---mac_length-->|
* ciphertext
*
* Returns std::size_t(-1) if the length of the cipher-text or the output
* buffer is too small. Otherwise returns the length of the output buffer.
*/
virtual std::size_t encrypt(
std::uint8_t const * key, std::size_t key_length,
std::uint8_t const * plaintext, std::size_t plaintext_length,
std::uint8_t * ciphertext, std::size_t ciphertext_length,
std::uint8_t * output, std::size_t output_length
) const = 0;
/**
* Returns the maximum length of plain-text that a given length of
* cipher-text can contain.
*/
virtual std::size_t decrypt_max_plaintext_length(
std::size_t ciphertext_length
) const = 0;
/**
* Authenticates the input and decrypts the cipher-text into the plain-text
* buffer.
*
* |----------------------------------------input_length-->|
* input |--ciphertext_length-->| |---mac_length-->|
* ciphertext
*
* Returns std::size_t(-1) if the length of the plain-text buffer is too
* small or if the authentication check fails. Otherwise returns the length
* of the plain text.
*/
virtual std::size_t decrypt(
std::uint8_t const * key, std::size_t key_length,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t const * ciphertext, std::size_t ciphertext_length,
std::uint8_t * plaintext, std::size_t max_plaintext_length
) const = 0;
};
class CipherAesSha256 : public Cipher {
public:
CipherAesSha256(
std::uint8_t const * kdf_info, std::size_t kdf_info_length
);
virtual std::size_t mac_length() const;
virtual std::size_t encrypt_ciphertext_length(
std::size_t plaintext_length
) const;
virtual std::size_t encrypt(
std::uint8_t const * key, std::size_t key_length,
std::uint8_t const * plaintext, std::size_t plaintext_length,
std::uint8_t * ciphertext, std::size_t ciphertext_length,
std::uint8_t * output, std::size_t output_length
) const;
virtual std::size_t decrypt_max_plaintext_length(
std::size_t ciphertext_length
) const;
virtual std::size_t decrypt(
std::uint8_t const * key, std::size_t key_length,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t const * ciphertext, std::size_t ciphertext_length,
std::uint8_t * plaintext, std::size_t max_plaintext_length
) const;
private:
std::uint8_t const * kdf_info;
std::size_t kdf_info_length;
};
} // namespace
#endif /* AXOLOTL_CIPHER_HH_ */
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