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