_ Git - BearSSL/blob - inc/bearssl_prf.h

   1 /*
   2  * Copyright (c) 2016 Thomas Pornin <pornin@bolet.org>
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining
   5  * a copy of this software and associated documentation files (the
   6  * "Software"), to deal in the Software without restriction, including
   7  * without limitation the rights to use, copy, modify, merge, publish,
   8  * distribute, sublicense, and/or sell copies of the Software, and to
   9  * permit persons to whom the Software is furnished to do so, subject to
  10  * the following conditions:
  11  *
  12  * The above copyright notice and this permission notice shall be
  13  * included in all copies or substantial portions of the Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18  * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  19  * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  20  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  21  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  22  * SOFTWARE.
  23  */
  24
  25 #ifndef BR_BEARSSL_PRF_H__
  26 #define BR_BEARSSL_PRF_H__
  27
  28 #include <stddef.h>
  29 #include <stdint.h>
  30
  31 /** \file bearssl_prf.h
  32  *
  33  * # The TLS PRF
  34  *
  35  * The "PRF" is the pseudorandom function used internally during the
  36  * SSL/TLS handshake, notably to expand negociated shared secrets into
  37  * the symmetric encryption keys that will be used to process the
  38  * application data.
  39  *
  40  * TLS 1.0 and 1.1 define a PRF that is based on both MD5 and SHA-1. This
  41  * is implemented by the `br_tls10_prf()` function.
  42  *
  43  * TLS 1.2 redefines the PRF, using an explicit hash function. The
  44  * `br_tls12_sha256_prf()` and `br_tls12_sha384_prf()` functions apply that
  45  * PRF with, respectively, SHA-256 and SHA-384. Most standard cipher suites
  46  * rely on the SHA-256 based PRF, but some use SHA-384.
  47  *
  48  * The PRF always uses as input three parameters: a "secret" (some
  49  * bytes), a "label" (ASCII string), and a "seed" (again some bytes).
  50  * An arbitrary output length can be produced.
  51  */
  52
  53 /** \brief PRF implementation for TLS 1.0 and 1.1.
  54  *
  55  * This PRF is the one specified by TLS 1.0 and 1.1. It internally uses
  56  * MD5 and SHA-1.
  57  *
  58  * \param dst          destination buffer.
  59  * \param len          output length (in bytes).
  60  * \param secret       secret value (key) for this computation.
  61  * \param secret_len   length of "secret" (in bytes).
  62  * \param label        PRF label (zero-terminated ASCII string).
  63  * \param seed         seed for this computation (usually non-secret).
  64  * \param seed_len     length of "seed" (in bytes).
  65  */
  66 void br_tls10_prf(void *dst, size_t len,
  67         const void *secret, size_t secret_len,
  68         const char *label, const void *seed, size_t seed_len);
  69
  70 /** \brief PRF implementation for TLS 1.2, with SHA-256.
  71  *
  72  * This PRF is the one specified by TLS 1.2, when the underlying hash
  73  * function is SHA-256.
  74  *
  75  * \param dst          destination buffer.
  76  * \param len          output length (in bytes).
  77  * \param secret       secret value (key) for this computation.
  78  * \param secret_len   length of "secret" (in bytes).
  79  * \param label        PRF label (zero-terminated ASCII string).
  80  * \param seed         seed for this computation (usually non-secret).
  81  * \param seed_len     length of "seed" (in bytes).
  82  */
  83 void br_tls12_sha256_prf(void *dst, size_t len,
  84         const void *secret, size_t secret_len,
  85         const char *label, const void *seed, size_t seed_len);
  86
  87 /** \brief PRF implementation for TLS 1.2, with SHA-384.
  88  *
  89  * This PRF is the one specified by TLS 1.2, when the underlying hash
  90  * function is SHA-384.
  91  *
  92  * \param dst          destination buffer.
  93  * \param len          output length (in bytes).
  94  * \param secret       secret value (key) for this computation.
  95  * \param secret_len   length of "secret" (in bytes).
  96  * \param label        PRF label (zero-terminated ASCII string).
  97  * \param seed         seed for this computation (usually non-secret).
  98  * \param seed_len     length of "seed" (in bytes).
  99  */
 100 void br_tls12_sha384_prf(void *dst, size_t len,
 101         const void *secret, size_t secret_len,
 102         const char *label, const void *seed, size_t seed_len);
 103
 104 /** \brief A convenient type name for a PRF implementation.
 105  *
 106  * \param dst          destination buffer.
 107  * \param len          output length (in bytes).
 108  * \param secret       secret value (key) for this computation.
 109  * \param secret_len   length of "secret" (in bytes).
 110  * \param label        PRF label (zero-terminated ASCII string).
 111  * \param seed         seed for this computation (usually non-secret).
 112  * \param seed_len     length of "seed" (in bytes).
 113  */
 114 typedef void (*br_tls_prf_impl)(void *dst, size_t len,
 115         const void *secret, size_t secret_len,
 116         const char *label, const void *seed, size_t seed_len);
 117
 118 #endif