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/* drbg-aes.h
*
* The CTR-AES-256-based random-number generator from SP800-90A.
*/
/* Copyright (C) 2013 Red Hat
*
* The nettle library is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or (at your
* option) any later version.
*
* The nettle library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with the nettle library; see the file COPYING.LIB. If not, write to
* the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
* MA 02111-1301, USA.
*/
#ifndef DRBG_AES_H_INCLUDED
#define DRBG_AES_H_INCLUDED
#include <config.h>
#include <nettle/aes.h>
/* This is nettle's increment macro */
/* Requires that size > 0 */
#define INCREMENT(size, ctr) \
do { \
unsigned increment_i = (size) - 1; \
if (++(ctr)[increment_i] == 0) \
while (increment_i > 0 \
&& ++(ctr)[--increment_i] == 0 ) \
; \
} while (0)
#define DRBG_AES_KEY_SIZE 32
#define DRBG_AES_SEED_SIZE (AES_BLOCK_SIZE+DRBG_AES_KEY_SIZE)
/* This is the CTR-AES-256-based random-number generator from SP800-90A.
*/
struct drbg_aes_ctx {
unsigned seeded;
/* The current key */
struct aes_ctx key;
uint8_t v[AES_BLOCK_SIZE];
unsigned prev_block_present;
uint8_t prev_block[AES_BLOCK_SIZE];
unsigned reseed_counter;
};
/* max_number_of_bits_per_request */
#define MAX_DRBG_AES_GENERATE_SIZE 65536 /* 2^19 */
/* This DRBG should be reseeded if reseed_counter exceeds
* that number. Otherwise drbg_aes_random() will fail.
*/
#define DRBG_AES_RESEED_TIME 16777216
/* The entropy provided in these functions should be of
* size DRBG_AES_SEED_SIZE. Additional data and pers.
* string may be <= DRBG_AES_SEED_SIZE.
*/
int
drbg_aes_init(struct drbg_aes_ctx *ctx,
unsigned entropy_size, const uint8_t *entropy,
unsigned pstring_size, const uint8_t* pstring);
int
drbg_aes_reseed(struct drbg_aes_ctx *ctx,
unsigned entropy_size, const uint8_t *entropy,
unsigned add_size, const uint8_t* add);
/* our wrapper for the low-level drbg_aes_generate */
int
drbg_aes_random(struct drbg_aes_ctx *ctx, unsigned length,
uint8_t * dst);
int
drbg_aes_generate(struct drbg_aes_ctx *ctx, unsigned length,
uint8_t * dst, unsigned add_size, const uint8_t* add);
/* For deinitialization use zeroize_key() on the context */
int drbg_aes_is_seeded(struct drbg_aes_ctx *ctx);
int drbg_aes_self_test(void);
#endif /* DRBG_AES_H_INCLUDED */
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