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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_CRYPTO_HH_
#define AXOLOTL_CRYPTO_HH_
#include <cstdint>
#include <cstddef>
namespace axolotl {
struct Curve25519PublicKey {
static const int LENGTH = 32;
std::uint8_t public_key[32];
};
struct Curve25519KeyPair : public Curve25519PublicKey {
static const int LENGTH = 64;
std::uint8_t private_key[32];
};
/** Generate a curve25519 key pair from 32 random bytes. */
void generate_key(
std::uint8_t const * random_32_bytes,
Curve25519KeyPair & key_pair
);
const std::size_t CURVE25519_SHARED_SECRET_LENGTH = 32;
/** Create a shared secret using our private key and their public key.
* The output buffer must be at least 32 bytes long. */
void curve25519_shared_secret(
Curve25519KeyPair const & our_key,
Curve25519PublicKey const & their_key,
std::uint8_t * output
);
/** Signs the message using our private key.
* The output buffer must be at least 64 bytes long. */
void curve25519_sign(
Curve25519KeyPair const & our_key,
std::uint8_t const * message, std::size_t message_length,
std::uint8_t * output
);
/** Verify thei message using their public key.
* The signature input buffer must be 64 bytes long.
* Returns true if the signature is valid. */
bool curve25519_verify(
Curve25519PublicKey const & their_key,
std::uint8_t const * message, std::size_t message_length,
std::uint8_t const * signature
);
struct Aes256Key {
static const int LENGTH = 32;
std::uint8_t key[32];
};
struct Aes256Iv {
static const int LENGTH = 16;
std::uint8_t iv[16];
};
/** The length of output the aes_encrypt_cbc function will write */
std::size_t aes_encrypt_cbc_length(
std::size_t input_length
);
/** Encrypts the input using AES256 in CBC mode with PKCS#7 padding.
* The output buffer must be big enough to hold the output including padding */
void aes_encrypt_cbc(
Aes256Key const & key,
Aes256Iv const & iv,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
/** Decrypts the input using AES256 in CBC mode. The output buffer must be at
* least the same size as the input buffer. Returns the length of the plaintext
* without padding on success or std::size_t(-1) if the padding is invalid.
*/
std::size_t aes_decrypt_cbc(
Aes256Key const & key,
Aes256Iv const & iv,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
/** Computes SHA-256 of the input. The output buffer must be a least 32
* bytes long. */
void sha256(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
const std::size_t HMAC_SHA256_OUTPUT_LENGTH = 32;
/** HMAC: Keyed-Hashing for Message Authentication
* http://tools.ietf.org/html/rfc2104
* Computes HMAC-SHA-256 of the input for the key. The output buffer must
* be at least 32 bytes long. */
void hmac_sha256(
std::uint8_t const * key, std::size_t key_length,
std::uint8_t const * input, std::size_t input_length,
std::uint8_t * output
);
/** HMAC-based Key Derivation Function (HKDF)
* https://tools.ietf.org/html/rfc5869
* Derives key material from the input bytes. */
void hkdf_sha256(
std::uint8_t const * input, std::size_t input_length,
std::uint8_t const * info, std::size_t info_length,
std::uint8_t const * salt, std::size_t salt_length,
std::uint8_t * output, std::size_t output_length
);
} // namespace axolotl
#endif /* AXOLOTL_CRYPTO_HH_ */
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