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 #define ECC_CURVE_NIST_P521 0x0004 30 31 /** 32 * struct ecdh - define an ECDH private key 33 * 34 * @key: Private ECDH key 35 * @key_size: Size of the private ECDH key 36 */ 37 struct ecdh { 38 char *key; 39 unsigned short key_size; 40 }; 41 42 /** 43 * crypto_ecdh_key_len() - Obtain the size of the private ECDH key 44 * @params: private ECDH key 45 * 46 * This function returns the packet ECDH key size. A caller can use that 47 * with the provided ECDH private key reference to obtain the required 48 * memory size to hold a packet key. 49 * 50 * Return: size of the key in bytes 51 */ 52 unsigned int crypto_ecdh_key_len(const struct ecdh *params); 53 54 /** 55 * crypto_ecdh_encode_key() - encode the private key 56 * @buf: Buffer allocated by the caller to hold the packet ECDH 57 * private key. The buffer should be at least crypto_ecdh_key_len 58 * bytes in size. 59 * @len: Length of the packet private key buffer 60 * @p: Buffer with the caller-specified private key 61 * 62 * The ECDH implementations operate on a packet representation of the private 63 * key. 64 * 65 * Return: -EINVAL if buffer has insufficient size, 0 on success 66 */ 67 int crypto_ecdh_encode_key(char *buf, unsigned int len, const struct ecdh *p); 68 69 /** 70 * crypto_ecdh_decode_key() - decode a private key 71 * @buf: Buffer holding a packet key that should be decoded 72 * @len: Length of the packet private key buffer 73 * @p: Buffer allocated by the caller that is filled with the 74 * unpacked ECDH private key. 75 * 76 * The unpacking obtains the private key by pointing @p to the correct location 77 * in @buf. Thus, both pointers refer to the same memory. 78 * 79 * Return: -EINVAL if buffer has insufficient size, 0 on success 80 */ 81 int crypto_ecdh_decode_key(const char *buf, unsigned int len, struct ecdh *p); 82 83 #endif 84