1/* SPDX-License-Identifier: GPL-2.0-or-later */ 2/* 3 * ECDH params to be used with kpp API 4 * 5 * Copyright (c) 2016, Intel Corporation 6 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com> 7 */ 8#ifndef _CRYPTO_ECDH_ 9#define _CRYPTO_ECDH_ 10 11/** 12 * DOC: ECDH Helper Functions 13 * 14 * To use ECDH with the KPP cipher API, the following data structure and 15 * functions should be used. 16 * 17 * The ECC curves known to the ECDH implementation are specified in this 18 * header file. 19 * 20 * To use ECDH with KPP, the following functions should be used to operate on 21 * an ECDH private key. The packet private key that can be set with 22 * the KPP API function call of crypto_kpp_set_secret. 23 */ 24 25/* Curves IDs */ 26#define ECC_CURVE_NIST_P192 0x0001 27#define ECC_CURVE_NIST_P256 0x0002 28#define ECC_CURVE_NIST_P384 0x0003 29 30/** 31 * struct ecdh - define an ECDH private key 32 * 33 * @curve_id: ECC curve the key is based on. 34 * @key: Private ECDH key 35 * @key_size: Size of the private ECDH key 36 */ 37struct ecdh { 38 unsigned short curve_id; 39 char *key; 40 unsigned short key_size; 41}; 42 43/** 44 * crypto_ecdh_key_len() - Obtain the size of the private ECDH key 45 * @params: private ECDH key 46 * 47 * This function returns the packet ECDH key size. A caller can use that 48 * with the provided ECDH private key reference to obtain the required 49 * memory size to hold a packet key. 50 * 51 * Return: size of the key in bytes 52 */ 53unsigned int crypto_ecdh_key_len(const struct ecdh *params); 54 55/** 56 * crypto_ecdh_encode_key() - encode the private key 57 * @buf: Buffer allocated by the caller to hold the packet ECDH 58 * private key. The buffer should be at least crypto_ecdh_key_len 59 * bytes in size. 60 * @len: Length of the packet private key buffer 61 * @p: Buffer with the caller-specified private key 62 * 63 * The ECDH implementations operate on a packet representation of the private 64 * key. 65 * 66 * Return: -EINVAL if buffer has insufficient size, 0 on success 67 */ 68int crypto_ecdh_encode_key(char *buf, unsigned int len, const struct ecdh *p); 69 70/** 71 * crypto_ecdh_decode_key() - decode a private key 72 * @buf: Buffer holding a packet key that should be decoded 73 * @len: Length of the packet private key buffer 74 * @p: Buffer allocated by the caller that is filled with the 75 * unpacked ECDH private key. 76 * 77 * The unpacking obtains the private key by pointing @p to the correct location 78 * in @buf. Thus, both pointers refer to the same memory. 79 * 80 * Return: -EINVAL if buffer has insufficient size, 0 on success 81 */ 82int crypto_ecdh_decode_key(const char *buf, unsigned int len, struct ecdh *p); 83 84#endif 85