tc_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.
 *
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 *  modification, are permitted provided that the following conditions are met:
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 *     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.
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 *    - Neither the name of Intel Corporation nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
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 *
 *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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 */

#ifndef __TC_HMAC_PRNG_H__
#define __TC_HMAC_PRNG_H__

#include "tc_sha256.h"
#include "tc_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__ */