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/* aes.h - TinyCrypt interface to an AES-128 implementation. */
/*
* Copyright (C) 2015 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.
*
* aes.h -- 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 aes128_set_encrypt/decrypt_key to set the key.
*
* 2) call aes_encrypt/decrypt to process the data.
*/
#ifndef __AES_H__
#define __AES_H__
#include<stdint.h>
#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 AES_BLOCK_SIZE (Nb*Nk)
#define AES_KEY_SIZE (Nb*Nk)
struct aes_key_sched_struct {
uint32_t words[Nb*(Nr+1)];
};
typedef struct aes_key_sched_struct *AesKeySched_t;
/*
* Set AES-128 encryption key.
*
* Effects: Uses key k to initialize s and returns 1.
*
* Exceptions: Returns 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.
*
*/
int32_t aes128_set_encrypt_key (
AesKeySched_t s, /* IN/OUT -- inited struct aes_key_sched_struct */
const uint8_t *k); /* IN -- points to the AES key */
/*
* AES-128 Encryption procedure.
*
* Assumes: s was initialized by aes_set_encrypt_key;
* out and in point to 16 byte buffers.
*
* Effects: Encrypts contents of in buffer into out buffer under key;
* schedule s and returns 1.
*
* Exceptions: Returns 0 if:
* out == NULL or
* in == NULL or
* s == NULL.
*/
int32_t aes_encrypt (
uint8_t *out, /* IN/OUT -- buffer to receive ciphertext block */
const uint8_t *in, /* IN -- a plaintext block to encrypt */
const AesKeySched_t s); /* IN -- initialized AES key schedule */
/*
* Set the AES-128 decryption key.
*
* Effects: Uses key k to initialize s and returns 1.
*
* Exceptions: Returns 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.
*
* 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.
*/
int32_t aes128_set_decrypt_key (
AesKeySched_t s, /* IN/OUT -- inited struct aes_key_sched_struct */
const uint8_t *k); /* IN -- points to the AES key */
/*
* AES-128 Encryption procedure.
*
* Assumes: s was initialized by aes_set_encrypt_key
* out and in point to 16 byte buffers.
*
* Effects: Decrypts in buffer into out buffer under key schedule s and
* returns 1.
*
* Exceptions: Returns 0 if:
* out is NULL or
* in is NULL or
* s is NULL.
*/
int32_t aes_decrypt (
uint8_t *out, /* IN/OUT -- buffer to receive ciphertext block */
const uint8_t *in, /* IN -- a plaintext block to encrypt */
const AesKeySched_t s); /* IN -- initialized AES key schedule */
#endif
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