1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (c) 2016, Intel Corporation
4 * Authors: Salvatore Benedetto <salvatore.benedetto@intel.com>
5 */
6#include <linux/kernel.h>
7#include <linux/export.h>
8#include <linux/err.h>
9#include <linux/string.h>
10#include <crypto/ecdh.h>
11#include <crypto/kpp.h>
12
13#define ECDH_KPP_SECRET_MIN_SIZE (sizeof(struct kpp_secret) + sizeof(short))
14
15static inline u8 *ecdh_pack_data(void *dst, const void *src, size_t sz)
16{
17 memcpy(dst, src, sz);
18 return dst + sz;
19}
20
21static inline const u8 *ecdh_unpack_data(void *dst, const void *src, size_t sz)
22{
23 memcpy(dst, src, sz);
24 return src + sz;
25}
26
27unsigned int crypto_ecdh_key_len(const struct ecdh *params)
28{
29 return ECDH_KPP_SECRET_MIN_SIZE + params->key_size;
30}
31EXPORT_SYMBOL_GPL(crypto_ecdh_key_len);
32
33int crypto_ecdh_encode_key(char *buf, unsigned int len,
34 const struct ecdh *params)
35{
36 u8 *ptr = buf;
37 struct kpp_secret secret = {
38 .type = CRYPTO_KPP_SECRET_TYPE_ECDH,
39 .len = len
40 };
41
42 if (unlikely(!buf))
43 return -EINVAL;
44
45 if (len != crypto_ecdh_key_len(params))
46 return -EINVAL;
47
48 ptr = ecdh_pack_data(dst: ptr, src: &secret, sz: sizeof(secret));
49 ptr = ecdh_pack_data(dst: ptr, src: &params->key_size, sz: sizeof(params->key_size));
50 ecdh_pack_data(dst: ptr, src: params->key, sz: params->key_size);
51
52 return 0;
53}
54EXPORT_SYMBOL_GPL(crypto_ecdh_encode_key);
55
56int crypto_ecdh_decode_key(const char *buf, unsigned int len,
57 struct ecdh *params)
58{
59 const u8 *ptr = buf;
60 struct kpp_secret secret;
61
62 if (unlikely(!buf || len < ECDH_KPP_SECRET_MIN_SIZE))
63 return -EINVAL;
64
65 ptr = ecdh_unpack_data(dst: &secret, src: ptr, sz: sizeof(secret));
66 if (secret.type != CRYPTO_KPP_SECRET_TYPE_ECDH)
67 return -EINVAL;
68
69 if (unlikely(len < secret.len))
70 return -EINVAL;
71
72 ptr = ecdh_unpack_data(dst: &params->key_size, src: ptr, sz: sizeof(params->key_size));
73 if (secret.len != crypto_ecdh_key_len(params))
74 return -EINVAL;
75
76 /* Don't allocate memory. Set pointer to data
77 * within the given buffer
78 */
79 params->key = (void *)ptr;
80
81 return 0;
82}
83EXPORT_SYMBOL_GPL(crypto_ecdh_decode_key);
84

source code of linux/crypto/ecdh_helper.c