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