1 /* 2 * ECDH params to be used with kpp API 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_ECDH_ 14 #define _CRYPTO_ECDH_ 15 16 /** 17 * DOC: ECDH Helper Functions 18 * 19 * To use ECDH with the KPP cipher API, the following data structure and 20 * functions should be used. 21 * 22 * The ECC curves known to the ECDH implementation are specified in this 23 * header file. 24 * 25 * To use ECDH with KPP, the following functions should be used to operate on 26 * an ECDH private key. The packet private key that can be set with 27 * the KPP API function call of crypto_kpp_set_secret. 28 */ 29 30 /* Curves IDs */ 31 #define ECC_CURVE_NIST_P192 0x0001 32 #define ECC_CURVE_NIST_P256 0x0002 33 34 /** 35 * struct ecdh - define an ECDH private key 36 * 37 * @curve_id: ECC curve the key is based on. 38 * @key: Private ECDH key 39 * @key_size: Size of the private ECDH key 40 */ 41 struct ecdh { 42 unsigned short curve_id; 43 char *key; 44 unsigned short key_size; 45 }; 46 47 /** 48 * crypto_ecdh_key_len() - Obtain the size of the private ECDH key 49 * @params: private ECDH key 50 * 51 * This function returns the packet ECDH key size. A caller can use that 52 * with the provided ECDH private key reference to obtain the required 53 * memory size to hold a packet key. 54 * 55 * Return: size of the key in bytes 56 */ 57 int crypto_ecdh_key_len(const struct ecdh *params); 58 59 /** 60 * crypto_ecdh_encode_key() - encode the private key 61 * @buf: Buffer allocated by the caller to hold the packet ECDH 62 * private key. The buffer should be at least crypto_ecdh_key_len 63 * bytes in size. 64 * @len: Length of the packet private key buffer 65 * @p: Buffer with the caller-specified private key 66 * 67 * The ECDH implementations operate on a packet representation of the private 68 * key. 69 * 70 * Return: -EINVAL if buffer has insufficient size, 0 on success 71 */ 72 int crypto_ecdh_encode_key(char *buf, unsigned int len, const struct ecdh *p); 73 74 /** 75 * crypto_ecdh_decode_key() - decode a private key 76 * @buf: Buffer holding a packet key that should be decoded 77 * @len: Lenth of the packet private key buffer 78 * @p: Buffer allocated by the caller that is filled with the 79 * unpacket ECDH private key. 80 * 81 * The unpacking obtains the private key by pointing @p to the correct location 82 * in @buf. Thus, both pointers refer to the same memory. 83 * 84 * Return: -EINVAL if buffer has insufficient size, 0 on success 85 */ 86 int crypto_ecdh_decode_key(const char *buf, unsigned int len, struct ecdh *p); 87 88 #endif 89