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/* aes.h - TinyCrypt interface to an AES-128 implementation */
/*
* Copyright (C) 2017 by Intel Corporation, All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* - Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Intel Corporation nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/**
* @file
* @brief -- Interface to an AES-128 implementation.
*
* Overview: AES-128 is a NIST approved block cipher specified in
* FIPS 197. Block ciphers are deterministic algorithms that
* perform a transformation specified by a symmetric key in fixed-
* length data sets, also called blocks.
*
* Security: AES-128 provides approximately 128 bits of security.
*
* Usage: 1) call tc_aes128_set_encrypt/decrypt_key to set the key.
*
* 2) call tc_aes_encrypt/decrypt to process the data.
*/
#ifndef __TC_AES_H__
#define __TC_AES_H__
#include <stdint.h>
#ifdef __cplusplus
extern "C" {
#endif
#define Nb (4) /* number of columns (32-bit words) comprising the state */
#define Nk (4) /* number of 32-bit words comprising the key */
#define Nr (10) /* number of rounds */
#define TC_AES_BLOCK_SIZE (Nb*Nk)
#define TC_AES_KEY_SIZE (Nb*Nk)
typedef struct tc_aes_key_sched_struct {
unsigned int words[Nb*(Nr+1)];
} *TCAesKeySched_t;
/**
* @brief Set AES-128 encryption key
* Uses key k to initialize s
* @return returns TC_CRYPTO_SUCCESS (1)
* returns TC_CRYPTO_FAIL (0) if: s == NULL or k == NULL
* @note This implementation skips the additional steps required for keys
* larger than 128 bits, and must not be used for AES-192 or
* AES-256 key schedule -- see FIPS 197 for details
* @param s IN/OUT -- initialized struct tc_aes_key_sched_struct
* @param k IN -- points to the AES key
*/
int tc_aes128_set_encrypt_key(TCAesKeySched_t s, const uint8_t *k);
/**
* @brief AES-128 Encryption procedure
* Encrypts contents of in buffer into out buffer under key;
* schedule s
* @note Assumes s was initialized by aes_set_encrypt_key;
* out and in point to 16 byte buffers
* @return returns TC_CRYPTO_SUCCESS (1)
* returns TC_CRYPTO_FAIL (0) if: out == NULL or in == NULL or s == NULL
* @param out IN/OUT -- buffer to receive ciphertext block
* @param in IN -- a plaintext block to encrypt
* @param s IN -- initialized AES key schedule
*/
int tc_aes_encrypt(uint8_t *out, const uint8_t *in,
const TCAesKeySched_t s);
/**
* @brief Set the AES-128 decryption key
* Uses key k to initialize s
* @return returns TC_CRYPTO_SUCCESS (1)
* returns TC_CRYPTO_FAIL (0) if: s == NULL or k == NULL
* @note This is the implementation of the straightforward inverse cipher
* using the cipher documented in FIPS-197 figure 12, not the
* equivalent inverse cipher presented in Figure 15
* @warning This routine skips the additional steps required for keys larger
* than 128, and must not be used for AES-192 or AES-256 key
* schedule -- see FIPS 197 for details
* @param s IN/OUT -- initialized struct tc_aes_key_sched_struct
* @param k IN -- points to the AES key
*/
int tc_aes128_set_decrypt_key(TCAesKeySched_t s, const uint8_t *k);
/**
* @brief AES-128 Encryption procedure
* Decrypts in buffer into out buffer under key schedule s
* @return returns TC_CRYPTO_SUCCESS (1)
* returns TC_CRYPTO_FAIL (0) if: out is NULL or in is NULL or s is NULL
* @note Assumes s was initialized by aes_set_encrypt_key
* out and in point to 16 byte buffers
* @param out IN/OUT -- buffer to receive ciphertext block
* @param in IN -- a plaintext block to encrypt
* @param s IN -- initialized AES key schedule
*/
int tc_aes_decrypt(uint8_t *out, const uint8_t *in,
const TCAesKeySched_t s);
#ifdef __cplusplus
}
#endif
#endif /* __TC_AES_H__ */
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