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 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: Lenth of the packet private key buffer 77 * @params: Buffer allocated by the caller that is filled with the 78 * unpacket 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 88