]>
Commit | Line | Data |
---|---|---|
3c4b2390 SB |
1 | /* ECDH key-agreement protocol |
2 | * | |
3 | * Copyright (c) 2016, Intel Corporation | |
4 | * Authors: Salvator Benedetto <salvatore.benedetto@intel.com> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public Licence | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the Licence, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <crypto/internal/kpp.h> | |
14 | #include <crypto/kpp.h> | |
15 | #include <crypto/ecdh.h> | |
16 | #include <linux/scatterlist.h> | |
17 | #include "ecc.h" | |
18 | ||
19 | struct ecdh_ctx { | |
20 | unsigned int curve_id; | |
21 | unsigned int ndigits; | |
22 | u64 private_key[ECC_MAX_DIGITS]; | |
23 | u64 public_key[2 * ECC_MAX_DIGITS]; | |
24 | u64 shared_secret[ECC_MAX_DIGITS]; | |
25 | }; | |
26 | ||
27 | static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm) | |
28 | { | |
29 | return kpp_tfm_ctx(tfm); | |
30 | } | |
31 | ||
32 | static unsigned int ecdh_supported_curve(unsigned int curve_id) | |
33 | { | |
34 | switch (curve_id) { | |
35 | case ECC_CURVE_NIST_P192: return 3; | |
36 | case ECC_CURVE_NIST_P256: return 4; | |
37 | default: return 0; | |
38 | } | |
39 | } | |
40 | ||
41 | static int ecdh_set_secret(struct crypto_kpp *tfm, void *buf, unsigned int len) | |
42 | { | |
43 | struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); | |
44 | struct ecdh params; | |
45 | unsigned int ndigits; | |
46 | ||
47 | if (crypto_ecdh_decode_key(buf, len, ¶ms) < 0) | |
48 | return -EINVAL; | |
49 | ||
50 | ndigits = ecdh_supported_curve(params.curve_id); | |
51 | if (!ndigits) | |
52 | return -EINVAL; | |
53 | ||
54 | ctx->curve_id = params.curve_id; | |
55 | ctx->ndigits = ndigits; | |
56 | ||
57 | if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits, | |
58 | (const u8 *)params.key, params.key_size) < 0) | |
59 | return -EINVAL; | |
60 | ||
61 | memcpy(ctx->private_key, params.key, params.key_size); | |
62 | ||
63 | return 0; | |
64 | } | |
65 | ||
66 | static int ecdh_compute_value(struct kpp_request *req) | |
67 | { | |
68 | int ret = 0; | |
69 | struct crypto_kpp *tfm = crypto_kpp_reqtfm(req); | |
70 | struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); | |
71 | size_t copied, nbytes; | |
72 | void *buf; | |
73 | ||
74 | nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT; | |
75 | ||
76 | if (req->src) { | |
77 | copied = sg_copy_to_buffer(req->src, 1, ctx->public_key, | |
78 | 2 * nbytes); | |
79 | if (copied != 2 * nbytes) | |
80 | return -EINVAL; | |
81 | ||
8f44df15 | 82 | ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits, |
3c4b2390 SB |
83 | (const u8 *)ctx->private_key, nbytes, |
84 | (const u8 *)ctx->public_key, 2 * nbytes, | |
85 | (u8 *)ctx->shared_secret, nbytes); | |
86 | ||
87 | buf = ctx->shared_secret; | |
88 | } else { | |
89 | ret = ecdh_make_pub_key(ctx->curve_id, ctx->ndigits, | |
90 | (const u8 *)ctx->private_key, nbytes, | |
91 | (u8 *)ctx->public_key, | |
92 | sizeof(ctx->public_key)); | |
93 | buf = ctx->public_key; | |
94 | /* Public part is a point thus it has both coordinates */ | |
95 | nbytes *= 2; | |
96 | } | |
97 | ||
98 | if (ret < 0) | |
99 | return ret; | |
100 | ||
101 | copied = sg_copy_from_buffer(req->dst, 1, buf, nbytes); | |
102 | if (copied != nbytes) | |
103 | return -EINVAL; | |
104 | ||
105 | return ret; | |
106 | } | |
107 | ||
108 | static int ecdh_max_size(struct crypto_kpp *tfm) | |
109 | { | |
110 | struct ecdh_ctx *ctx = ecdh_get_ctx(tfm); | |
111 | int nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT; | |
112 | ||
113 | /* Public key is made of two coordinates */ | |
114 | return 2 * nbytes; | |
115 | } | |
116 | ||
117 | static void no_exit_tfm(struct crypto_kpp *tfm) | |
118 | { | |
119 | return; | |
120 | } | |
121 | ||
122 | static struct kpp_alg ecdh = { | |
123 | .set_secret = ecdh_set_secret, | |
124 | .generate_public_key = ecdh_compute_value, | |
125 | .compute_shared_secret = ecdh_compute_value, | |
126 | .max_size = ecdh_max_size, | |
127 | .exit = no_exit_tfm, | |
128 | .base = { | |
129 | .cra_name = "ecdh", | |
130 | .cra_driver_name = "ecdh-generic", | |
131 | .cra_priority = 100, | |
132 | .cra_module = THIS_MODULE, | |
133 | .cra_ctxsize = sizeof(struct ecdh_ctx), | |
134 | }, | |
135 | }; | |
136 | ||
137 | static int ecdh_init(void) | |
138 | { | |
139 | return crypto_register_kpp(&ecdh); | |
140 | } | |
141 | ||
142 | static void ecdh_exit(void) | |
143 | { | |
144 | crypto_unregister_kpp(&ecdh); | |
145 | } | |
146 | ||
147 | module_init(ecdh_init); | |
148 | module_exit(ecdh_exit); | |
149 | MODULE_ALIAS_CRYPTO("ecdh"); | |
150 | MODULE_LICENSE("GPL"); | |
151 | MODULE_DESCRIPTION("ECDH generic algorithm"); |