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d2e9e320 RS |
1 | /* |
2 | * Copyright 2016 The OpenSSL Project Authors. All Rights Reserved. | |
aacfb134 | 3 | * |
d2e9e320 RS |
4 | * Licensed under the OpenSSL license (the "License"). You may not use |
5 | * this file except in compliance with the License. You can obtain a copy | |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
aacfb134 AG |
8 | */ |
9 | ||
10 | #include <stdlib.h> | |
11 | #include <string.h> | |
12 | #include <openssl/hmac.h> | |
13 | #include <openssl/kdf.h> | |
14 | #include <openssl/evp.h> | |
15 | #include "internal/cryptlib.h" | |
16 | #include "internal/evp_int.h" | |
17 | ||
18 | #define HKDF_MAXBUF 1024 | |
19 | ||
20 | static unsigned char *HKDF(const EVP_MD *evp_md, | |
21 | const unsigned char *salt, size_t salt_len, | |
22 | const unsigned char *key, size_t key_len, | |
23 | const unsigned char *info, size_t info_len, | |
24 | unsigned char *okm, size_t okm_len); | |
25 | ||
26 | static unsigned char *HKDF_Extract(const EVP_MD *evp_md, | |
27 | const unsigned char *salt, size_t salt_len, | |
28 | const unsigned char *key, size_t key_len, | |
29 | unsigned char *prk, size_t *prk_len); | |
30 | ||
31 | static unsigned char *HKDF_Expand(const EVP_MD *evp_md, | |
32 | const unsigned char *prk, size_t prk_len, | |
33 | const unsigned char *info, size_t info_len, | |
34 | unsigned char *okm, size_t okm_len); | |
35 | ||
36 | typedef struct { | |
37 | const EVP_MD *md; | |
38 | unsigned char *salt; | |
39 | size_t salt_len; | |
40 | unsigned char *key; | |
41 | size_t key_len; | |
42 | unsigned char info[HKDF_MAXBUF]; | |
43 | size_t info_len; | |
44 | } HKDF_PKEY_CTX; | |
45 | ||
46 | static int pkey_hkdf_init(EVP_PKEY_CTX *ctx) | |
47 | { | |
48 | HKDF_PKEY_CTX *kctx; | |
49 | ||
50 | kctx = OPENSSL_zalloc(sizeof(*kctx)); | |
51 | if (kctx == NULL) | |
52 | return 0; | |
53 | ||
54 | ctx->data = kctx; | |
55 | ||
56 | return 1; | |
57 | } | |
58 | ||
59 | static void pkey_hkdf_cleanup(EVP_PKEY_CTX *ctx) | |
60 | { | |
61 | HKDF_PKEY_CTX *kctx = ctx->data; | |
62 | OPENSSL_clear_free(kctx->salt, kctx->salt_len); | |
63 | OPENSSL_clear_free(kctx->key, kctx->key_len); | |
64 | OPENSSL_cleanse(kctx->info, kctx->info_len); | |
65 | OPENSSL_free(kctx); | |
66 | } | |
67 | ||
68 | static int pkey_hkdf_ctrl(EVP_PKEY_CTX *ctx, int type, int p1, void *p2) | |
69 | { | |
70 | HKDF_PKEY_CTX *kctx = ctx->data; | |
71 | ||
72 | switch (type) { | |
73 | case EVP_PKEY_CTRL_HKDF_MD: | |
74 | if (p2 == NULL) | |
75 | return 0; | |
76 | ||
77 | kctx->md = p2; | |
78 | return 1; | |
79 | ||
80 | case EVP_PKEY_CTRL_HKDF_SALT: | |
81 | if (p1 == 0 || p2 == NULL) | |
82 | return 1; | |
83 | ||
84 | if (p1 < 0) | |
85 | return 0; | |
86 | ||
87 | if (kctx->salt != NULL) | |
88 | OPENSSL_clear_free(kctx->salt, kctx->salt_len); | |
89 | ||
90 | kctx->salt = OPENSSL_memdup(p2, p1); | |
91 | if (kctx->salt == NULL) | |
92 | return 0; | |
93 | ||
94 | kctx->salt_len = p1; | |
95 | return 1; | |
96 | ||
97 | case EVP_PKEY_CTRL_HKDF_KEY: | |
98 | if (p1 < 0) | |
99 | return 0; | |
100 | ||
101 | if (kctx->key != NULL) | |
102 | OPENSSL_clear_free(kctx->key, kctx->key_len); | |
103 | ||
104 | kctx->key = OPENSSL_memdup(p2, p1); | |
105 | if (kctx->key == NULL) | |
106 | return 0; | |
107 | ||
108 | kctx->key_len = p1; | |
109 | return 1; | |
110 | ||
111 | case EVP_PKEY_CTRL_HKDF_INFO: | |
112 | if (p1 == 0 || p2 == NULL) | |
113 | return 1; | |
114 | ||
115 | if (p1 < 0 || p1 > (int)(HKDF_MAXBUF - kctx->info_len)) | |
116 | return 0; | |
117 | ||
118 | memcpy(kctx->info + kctx->info_len, p2, p1); | |
119 | kctx->info_len += p1; | |
120 | return 1; | |
121 | ||
122 | default: | |
123 | return -2; | |
124 | ||
125 | } | |
126 | } | |
127 | ||
128 | static int pkey_hkdf_ctrl_str(EVP_PKEY_CTX *ctx, const char *type, | |
129 | const char *value) | |
130 | { | |
131 | if (strcmp(type, "md") == 0) | |
132 | return EVP_PKEY_CTX_set_hkdf_md(ctx, EVP_get_digestbyname(value)); | |
133 | ||
134 | if (strcmp(type, "salt") == 0) | |
135 | return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value); | |
136 | ||
137 | if (strcmp(type, "hexsalt") == 0) | |
138 | return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_SALT, value); | |
139 | ||
140 | if (strcmp(type, "key") == 0) | |
141 | return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value); | |
142 | ||
143 | if (strcmp(type, "hexkey") == 0) | |
144 | return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_KEY, value); | |
145 | ||
146 | if (strcmp(type, "info") == 0) | |
147 | return EVP_PKEY_CTX_str2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value); | |
148 | ||
149 | if (strcmp(type, "hexinfo") == 0) | |
150 | return EVP_PKEY_CTX_hex2ctrl(ctx, EVP_PKEY_CTRL_HKDF_INFO, value); | |
151 | ||
152 | return -2; | |
153 | } | |
154 | ||
155 | static int pkey_hkdf_derive(EVP_PKEY_CTX *ctx, unsigned char *key, | |
156 | size_t *keylen) | |
157 | { | |
158 | HKDF_PKEY_CTX *kctx = ctx->data; | |
159 | ||
160 | if (kctx->md == NULL || kctx->key == NULL) | |
161 | return 0; | |
162 | ||
163 | if (HKDF(kctx->md, kctx->salt, kctx->salt_len, kctx->key, kctx->key_len, | |
164 | kctx->info, kctx->info_len, key, *keylen) == NULL) | |
165 | { | |
166 | return 0; | |
167 | } | |
168 | ||
169 | return 1; | |
170 | } | |
171 | ||
172 | const EVP_PKEY_METHOD hkdf_pkey_meth = { | |
173 | EVP_PKEY_HKDF, | |
174 | 0, | |
175 | pkey_hkdf_init, | |
176 | 0, | |
177 | pkey_hkdf_cleanup, | |
178 | ||
179 | 0, 0, | |
180 | 0, 0, | |
181 | ||
182 | 0, | |
183 | 0, | |
184 | ||
185 | 0, | |
186 | 0, | |
187 | ||
188 | 0, 0, | |
189 | ||
190 | 0, 0, 0, 0, | |
191 | ||
192 | 0, 0, | |
193 | ||
194 | 0, 0, | |
195 | ||
196 | 0, | |
197 | pkey_hkdf_derive, | |
198 | pkey_hkdf_ctrl, | |
199 | pkey_hkdf_ctrl_str | |
200 | }; | |
201 | ||
202 | static unsigned char *HKDF(const EVP_MD *evp_md, | |
203 | const unsigned char *salt, size_t salt_len, | |
204 | const unsigned char *key, size_t key_len, | |
205 | const unsigned char *info, size_t info_len, | |
206 | unsigned char *okm, size_t okm_len) | |
207 | { | |
208 | unsigned char prk[EVP_MAX_MD_SIZE]; | |
209 | size_t prk_len; | |
210 | ||
211 | if (!HKDF_Extract(evp_md, salt, salt_len, key, key_len, prk, &prk_len)) | |
212 | return NULL; | |
213 | ||
214 | return HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len); | |
215 | } | |
216 | ||
217 | static unsigned char *HKDF_Extract(const EVP_MD *evp_md, | |
218 | const unsigned char *salt, size_t salt_len, | |
219 | const unsigned char *key, size_t key_len, | |
220 | unsigned char *prk, size_t *prk_len) | |
221 | { | |
222 | unsigned int tmp_len; | |
223 | ||
224 | if (!HMAC(evp_md, salt, salt_len, key, key_len, prk, &tmp_len)) | |
225 | return NULL; | |
226 | ||
227 | *prk_len = tmp_len; | |
228 | return prk; | |
229 | } | |
230 | ||
231 | static unsigned char *HKDF_Expand(const EVP_MD *evp_md, | |
232 | const unsigned char *prk, size_t prk_len, | |
233 | const unsigned char *info, size_t info_len, | |
234 | unsigned char *okm, size_t okm_len) | |
235 | { | |
236 | HMAC_CTX *hmac; | |
237 | ||
238 | unsigned int i; | |
239 | ||
240 | unsigned char prev[EVP_MAX_MD_SIZE]; | |
241 | ||
242 | size_t done_len = 0, dig_len = EVP_MD_size(evp_md); | |
243 | ||
244 | size_t n = okm_len / dig_len; | |
245 | if (okm_len % dig_len) | |
246 | n++; | |
247 | ||
248 | if (n > 255) | |
249 | return NULL; | |
250 | ||
251 | if ((hmac = HMAC_CTX_new()) == NULL) | |
252 | return NULL; | |
253 | ||
254 | if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL)) | |
255 | goto err; | |
256 | ||
257 | for (i = 1; i <= n; i++) { | |
258 | size_t copy_len; | |
259 | const unsigned char ctr = i; | |
260 | ||
261 | if (i > 1) { | |
262 | if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL)) | |
263 | goto err; | |
264 | ||
265 | if (!HMAC_Update(hmac, prev, dig_len)) | |
266 | goto err; | |
267 | } | |
268 | ||
269 | if (!HMAC_Update(hmac, info, info_len)) | |
270 | goto err; | |
271 | ||
272 | if (!HMAC_Update(hmac, &ctr, 1)) | |
273 | goto err; | |
274 | ||
275 | if (!HMAC_Final(hmac, prev, NULL)) | |
276 | goto err; | |
277 | ||
278 | copy_len = (done_len + dig_len > okm_len) ? | |
279 | okm_len - done_len : | |
280 | dig_len; | |
281 | ||
282 | memcpy(okm + done_len, prev, copy_len); | |
283 | ||
284 | done_len += copy_len; | |
285 | } | |
286 | ||
287 | HMAC_CTX_free(hmac); | |
288 | return okm; | |
289 | ||
290 | err: | |
291 | HMAC_CTX_free(hmac); | |
292 | return NULL; | |
293 | } |