1*4882a593Smuzhiyun /* SPDX-License-Identifier: GPL-2.0-or-later */ 2*4882a593Smuzhiyun /* 3*4882a593Smuzhiyun * ECDH params to be used with kpp API 4*4882a593Smuzhiyun * 5*4882a593Smuzhiyun * Copyright (c) 2016, Intel Corporation 6*4882a593Smuzhiyun * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com> 7*4882a593Smuzhiyun */ 8*4882a593Smuzhiyun #ifndef _CRYPTO_ECDH_ 9*4882a593Smuzhiyun #define _CRYPTO_ECDH_ 10*4882a593Smuzhiyun 11*4882a593Smuzhiyun /** 12*4882a593Smuzhiyun * DOC: ECDH Helper Functions 13*4882a593Smuzhiyun * 14*4882a593Smuzhiyun * To use ECDH with the KPP cipher API, the following data structure and 15*4882a593Smuzhiyun * functions should be used. 16*4882a593Smuzhiyun * 17*4882a593Smuzhiyun * The ECC curves known to the ECDH implementation are specified in this 18*4882a593Smuzhiyun * header file. 19*4882a593Smuzhiyun * 20*4882a593Smuzhiyun * To use ECDH with KPP, the following functions should be used to operate on 21*4882a593Smuzhiyun * an ECDH private key. The packet private key that can be set with 22*4882a593Smuzhiyun * the KPP API function call of crypto_kpp_set_secret. 23*4882a593Smuzhiyun */ 24*4882a593Smuzhiyun 25*4882a593Smuzhiyun /* Curves IDs */ 26*4882a593Smuzhiyun #define ECC_CURVE_NIST_P192 0x0001 27*4882a593Smuzhiyun #define ECC_CURVE_NIST_P256 0x0002 28*4882a593Smuzhiyun 29*4882a593Smuzhiyun /** 30*4882a593Smuzhiyun * struct ecdh - define an ECDH private key 31*4882a593Smuzhiyun * 32*4882a593Smuzhiyun * @curve_id: ECC curve the key is based on. 33*4882a593Smuzhiyun * @key: Private ECDH key 34*4882a593Smuzhiyun * @key_size: Size of the private ECDH key 35*4882a593Smuzhiyun */ 36*4882a593Smuzhiyun struct ecdh { 37*4882a593Smuzhiyun unsigned short curve_id; 38*4882a593Smuzhiyun char *key; 39*4882a593Smuzhiyun unsigned short key_size; 40*4882a593Smuzhiyun }; 41*4882a593Smuzhiyun 42*4882a593Smuzhiyun /** 43*4882a593Smuzhiyun * crypto_ecdh_key_len() - Obtain the size of the private ECDH key 44*4882a593Smuzhiyun * @params: private ECDH key 45*4882a593Smuzhiyun * 46*4882a593Smuzhiyun * This function returns the packet ECDH key size. A caller can use that 47*4882a593Smuzhiyun * with the provided ECDH private key reference to obtain the required 48*4882a593Smuzhiyun * memory size to hold a packet key. 49*4882a593Smuzhiyun * 50*4882a593Smuzhiyun * Return: size of the key in bytes 51*4882a593Smuzhiyun */ 52*4882a593Smuzhiyun unsigned int crypto_ecdh_key_len(const struct ecdh *params); 53*4882a593Smuzhiyun 54*4882a593Smuzhiyun /** 55*4882a593Smuzhiyun * crypto_ecdh_encode_key() - encode the private key 56*4882a593Smuzhiyun * @buf: Buffer allocated by the caller to hold the packet ECDH 57*4882a593Smuzhiyun * private key. The buffer should be at least crypto_ecdh_key_len 58*4882a593Smuzhiyun * bytes in size. 59*4882a593Smuzhiyun * @len: Length of the packet private key buffer 60*4882a593Smuzhiyun * @p: Buffer with the caller-specified private key 61*4882a593Smuzhiyun * 62*4882a593Smuzhiyun * The ECDH implementations operate on a packet representation of the private 63*4882a593Smuzhiyun * key. 64*4882a593Smuzhiyun * 65*4882a593Smuzhiyun * Return: -EINVAL if buffer has insufficient size, 0 on success 66*4882a593Smuzhiyun */ 67*4882a593Smuzhiyun int crypto_ecdh_encode_key(char *buf, unsigned int len, const struct ecdh *p); 68*4882a593Smuzhiyun 69*4882a593Smuzhiyun /** 70*4882a593Smuzhiyun * crypto_ecdh_decode_key() - decode a private key 71*4882a593Smuzhiyun * @buf: Buffer holding a packet key that should be decoded 72*4882a593Smuzhiyun * @len: Length of the packet private key buffer 73*4882a593Smuzhiyun * @p: Buffer allocated by the caller that is filled with the 74*4882a593Smuzhiyun * unpacked ECDH private key. 75*4882a593Smuzhiyun * 76*4882a593Smuzhiyun * The unpacking obtains the private key by pointing @p to the correct location 77*4882a593Smuzhiyun * in @buf. Thus, both pointers refer to the same memory. 78*4882a593Smuzhiyun * 79*4882a593Smuzhiyun * Return: -EINVAL if buffer has insufficient size, 0 on success 80*4882a593Smuzhiyun */ 81*4882a593Smuzhiyun int crypto_ecdh_decode_key(const char *buf, unsigned int len, struct ecdh *p); 82*4882a593Smuzhiyun 83*4882a593Smuzhiyun #endif 84