include/crypto/dh.h

   1 /*
   2  * Diffie-Hellman secret to be used with kpp API along with helper functions
   3  *
   4  * Copyright (c) 2016, Intel Corporation
   5  * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the Free
   9  * Software Foundation; either version 2 of the License, or (at your option)
  10  * any later version.
  11  *
  12  */
  13 #ifndef _CRYPTO_DH_
  14 #define _CRYPTO_DH_
  15
  16 /**
  17  * DOC: DH Helper Functions
  18  *
  19  * To use DH with the KPP cipher API, the following data structure and
  20  * functions should be used.
  21  *
  22  * To use DH with KPP, the following functions should be used to operate on
  23  * a DH private key. The packet private key that can be set with
  24  * the KPP API function call of crypto_kpp_set_secret.
  25  */
  26
  27 /**
  28  * struct dh - define a DH private key
  29  *
  30  * @key:        Private DH key
  31  * @p:          Diffie-Hellman parameter P
  32  * @g:          Diffie-Hellman generator G
  33  * @key_size:   Size of the private DH key
  34  * @p_size:     Size of DH parameter P
  35  * @g_size:     Size of DH generator G
  36  */
  37 struct dh {
  38         void *key;
  39         void *p;
  40         void *g;
  41         unsigned int key_size;
  42         unsigned int p_size;
  43         unsigned int g_size;
  44 };
  45
  46 /**
  47  * crypto_dh_key_len() - Obtain the size of the private DH key
  48  * @params:     private DH key
  49  *
  50  * This function returns the packet DH key size. A caller can use that
  51  * with the provided DH private key reference to obtain the required
  52  * memory size to hold a packet key.
  53  *
  54  * Return: size of the key in bytes
  55  */
  56 unsigned int crypto_dh_key_len(const struct dh *params);
  57
  58 /**
  59  * crypto_dh_encode_key() - encode the private key
  60  * @buf:        Buffer allocated by the caller to hold the packet DH
  61  *              private key. The buffer should be at least crypto_dh_key_len
  62  *              bytes in size.
  63  * @len:        Length of the packet private key buffer
  64  * @params:     Buffer with the caller-specified private key
  65  *
  66  * The DH implementations operate on a packet representation of the private
  67  * key.
  68  *
  69  * Return:      -EINVAL if buffer has insufficient size, 0 on success
  70  */
  71 int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params);
  72
  73 /**
  74  * crypto_dh_decode_key() - decode a private key
  75  * @buf:        Buffer holding a packet key that should be decoded
  76  * @len:        Length of the packet private key buffer
  77  * @params:     Buffer allocated by the caller that is filled with the
  78  *              unpacked DH private key.
  79  *
  80  * The unpacking obtains the private key by pointing @p to the correct location
  81  * in @buf. Thus, both pointers refer to the same memory.
  82  *
  83  * Return:      -EINVAL if buffer has insufficient size, 0 on success
  84  */
  85 int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params);
  86
  87 #endif