1/*
2 * Copyright (c) 2016, Intel Corporation
3 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 */
10#include <linux/kernel.h>
11#include <linux/export.h>
12#include <linux/err.h>
13#include <linux/string.h>
14#include <crypto/ecdh.h>
15#include <crypto/kpp.h>
16
17#define ECDH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + 2 * sizeof(short))
18
19static inline u8 *ecdh_pack_data(void *dst, const void *src, size_t sz)
20{
21 memcpy(dst, src, sz);
22 return dst + sz;
23}
24
25static inline const u8 *ecdh_unpack_data(void *dst, const void *src, size_t sz)
26{
27 memcpy(dst, src, sz);
28 return src + sz;
29}
30
31unsigned int crypto_ecdh_key_len(const struct ecdh *params)
32{
33 return ECDH_KPP_SECRET_MIN_SIZE + params->key_size;
34}
35EXPORT_SYMBOL_GPL(crypto_ecdh_key_len);
36
37int crypto_ecdh_encode_key(char *buf, unsigned int len,
38 const struct ecdh *params)
39{
40 u8 *ptr = buf;
41 struct kpp_secret secret = {
42 .type = CRYPTO_KPP_SECRET_TYPE_ECDH,
43 .len = len
44 };
45
46 if (unlikely(!buf))
47 return -EINVAL;
48
49 if (len != crypto_ecdh_key_len(params))
50 return -EINVAL;
51
52 ptr = ecdh_pack_data(ptr, &secret, sizeof(secret));
53 ptr = ecdh_pack_data(ptr, &params->curve_id, sizeof(params->curve_id));
54 ptr = ecdh_pack_data(ptr, &params->key_size, sizeof(params->key_size));
55 ecdh_pack_data(ptr, params->key, params->key_size);
56
57 return 0;
58}
59EXPORT_SYMBOL_GPL(crypto_ecdh_encode_key);
60
61int crypto_ecdh_decode_key(const char *buf, unsigned int len,
62 struct ecdh *params)
63{
64 const u8 *ptr = buf;
65 struct kpp_secret secret;
66
67 if (unlikely(!buf || len < ECDH_KPP_SECRET_MIN_SIZE))
68 return -EINVAL;
69
70 ptr = ecdh_unpack_data(&secret, ptr, sizeof(secret));
71 if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
72 return -EINVAL;
73
74 ptr = ecdh_unpack_data(&params->curve_id, ptr, sizeof(params->curve_id));
75 ptr = ecdh_unpack_data(&params->key_size, ptr, sizeof(params->key_size));
76 if (secret.len != crypto_ecdh_key_len(params))
77 return -EINVAL;
78
79 /* Don't allocate memory. Set pointer to data
80 * within the given buffer
81 */
82 params->key = (void *)ptr;
83
84 return 0;
85}
86EXPORT_SYMBOL_GPL(crypto_ecdh_decode_key);
87