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