hmac_prng.h

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/* hmac_prng.h - TinyCrypt interface to an HMAC-PRNG 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
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 *  POSSIBILITY OF SUCH DAMAGE.
 */
 
#ifndef __TC_HMAC_PRNG_H__
#define __TC_HMAC_PRNG_H__
 
#include "sha256.h"
#include "hmac.h"
 
#ifdef __cplusplus
extern "C" {
#endif
 
#define TC_HMAC_PRNG_RESEED_REQ -1
 
struct tc_hmac_prng_struct {
    /* the HMAC instance for this PRNG */
    struct tc_hmac_state_struct h;
    /* the PRNG key */
    uint8_t key[TC_SHA256_DIGEST_SIZE];
    /* PRNG state */
    uint8_t v[TC_SHA256_DIGEST_SIZE];
    /* calls to tc_hmac_prng_generate left before re-seed */
    unsigned int countdown;
};
 
typedef struct tc_hmac_prng_struct *TCHmacPrng_t;
 
int tc_hmac_prng_init(TCHmacPrng_t prng,
              const uint8_t *personalization,
              unsigned int plen);
 
int tc_hmac_prng_reseed(TCHmacPrng_t prng, const uint8_t *seed,
            unsigned int seedlen, const uint8_t *additional_input,
            unsigned int additionallen);
 
int tc_hmac_prng_generate(uint8_t *out, unsigned int outlen, TCHmacPrng_t prng);
 
#ifdef __cplusplus
}
#endif
 
#endif /* __TC_HMAC_PRNG_H__ */