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 * @q: Diffie-Hellman parameter Q 33 * @g: Diffie-Hellman generator G 34 * @key_size: Size of the private DH key 35 * @p_size: Size of DH parameter P 36 * @q_size: Size of DH parameter Q 37 * @g_size: Size of DH generator G 38 */ 39struct dh { 40 void *key; 41 void *p; 42 void *q; 43 void *g; 44 unsigned int key_size; 45 unsigned int p_size; 46 unsigned int q_size; 47 unsigned int g_size; 48}; 49 50/** 51 * crypto_dh_key_len() - Obtain the size of the private DH key 52 * @params: private DH key 53 * 54 * This function returns the packet DH key size. A caller can use that 55 * with the provided DH private key reference to obtain the required 56 * memory size to hold a packet key. 57 * 58 * Return: size of the key in bytes 59 */ 60unsigned int crypto_dh_key_len(const struct dh *params); 61 62/** 63 * crypto_dh_encode_key() - encode the private key 64 * @buf: Buffer allocated by the caller to hold the packet DH 65 * private key. The buffer should be at least crypto_dh_key_len 66 * bytes in size. 67 * @len: Length of the packet private key buffer 68 * @params: Buffer with the caller-specified private key 69 * 70 * The DH implementations operate on a packet representation of the private 71 * key. 72 * 73 * Return: -EINVAL if buffer has insufficient size, 0 on success 74 */ 75int crypto_dh_encode_key(char *buf, unsigned int len, const struct dh *params); 76 77/** 78 * crypto_dh_decode_key() - decode a private key 79 * @buf: Buffer holding a packet key that should be decoded 80 * @len: Length of the packet private key buffer 81 * @params: Buffer allocated by the caller that is filled with the 82 * unpacked DH private key. 83 * 84 * The unpacking obtains the private key by pointing @p to the correct location 85 * in @buf. Thus, both pointers refer to the same memory. 86 * 87 * Return: -EINVAL if buffer has insufficient size, 0 on success 88 */ 89int crypto_dh_decode_key(const char *buf, unsigned int len, struct dh *params); 90 91#endif 92