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Commit | Line | Data |
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d2e9e320 | 1 | /* |
28428130 | 2 | * Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved. |
aacfb134 | 3 | * |
7bb803e8 | 4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
d2e9e320 RS |
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> | |
5a285add | 11 | #include <stdarg.h> |
aacfb134 AG |
12 | #include <string.h> |
13 | #include <openssl/hmac.h> | |
aacfb134 | 14 | #include <openssl/evp.h> |
5a285add | 15 | #include <openssl/kdf.h> |
aacfb134 | 16 | #include "internal/cryptlib.h" |
cee719c2 | 17 | #include "internal/numbers.h" |
aacfb134 | 18 | #include "internal/evp_int.h" |
5a285add | 19 | #include "kdf_local.h" |
aacfb134 AG |
20 | |
21 | #define HKDF_MAXBUF 1024 | |
22 | ||
5a285add DM |
23 | static void kdf_hkdf_reset(EVP_KDF_IMPL *impl); |
24 | static int HKDF(const EVP_MD *evp_md, | |
25 | const unsigned char *salt, size_t salt_len, | |
26 | const unsigned char *key, size_t key_len, | |
27 | const unsigned char *info, size_t info_len, | |
28 | unsigned char *okm, size_t okm_len); | |
29 | static int HKDF_Extract(const EVP_MD *evp_md, | |
30 | const unsigned char *salt, size_t salt_len, | |
e7018588 | 31 | const unsigned char *ikm, size_t ikm_len, |
5a285add DM |
32 | unsigned char *prk, size_t prk_len); |
33 | static int HKDF_Expand(const EVP_MD *evp_md, | |
34 | const unsigned char *prk, size_t prk_len, | |
35 | const unsigned char *info, size_t info_len, | |
36 | unsigned char *okm, size_t okm_len); | |
37 | ||
38 | struct evp_kdf_impl_st { | |
d2139cf8 | 39 | int mode; |
aacfb134 AG |
40 | const EVP_MD *md; |
41 | unsigned char *salt; | |
42 | size_t salt_len; | |
43 | unsigned char *key; | |
44 | size_t key_len; | |
45 | unsigned char info[HKDF_MAXBUF]; | |
46 | size_t info_len; | |
5a285add | 47 | }; |
aacfb134 | 48 | |
5a285add | 49 | static EVP_KDF_IMPL *kdf_hkdf_new(void) |
aacfb134 | 50 | { |
5a285add | 51 | EVP_KDF_IMPL *impl; |
aacfb134 | 52 | |
5a285add DM |
53 | if ((impl = OPENSSL_zalloc(sizeof(*impl))) == NULL) |
54 | KDFerr(KDF_F_KDF_HKDF_NEW, ERR_R_MALLOC_FAILURE); | |
55 | return impl; | |
56 | } | |
aacfb134 | 57 | |
5a285add DM |
58 | static void kdf_hkdf_free(EVP_KDF_IMPL *impl) |
59 | { | |
60 | kdf_hkdf_reset(impl); | |
61 | OPENSSL_free(impl); | |
aacfb134 AG |
62 | } |
63 | ||
5a285add | 64 | static void kdf_hkdf_reset(EVP_KDF_IMPL *impl) |
aacfb134 | 65 | { |
5a285add DM |
66 | OPENSSL_free(impl->salt); |
67 | OPENSSL_clear_free(impl->key, impl->key_len); | |
68 | OPENSSL_cleanse(impl->info, impl->info_len); | |
69 | memset(impl, 0, sizeof(*impl)); | |
aacfb134 AG |
70 | } |
71 | ||
5a285add | 72 | static int kdf_hkdf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args) |
aacfb134 | 73 | { |
5a285add DM |
74 | const unsigned char *p; |
75 | size_t len; | |
76 | const EVP_MD *md; | |
aacfb134 | 77 | |
5a285add DM |
78 | switch (cmd) { |
79 | case EVP_KDF_CTRL_SET_MD: | |
80 | md = va_arg(args, const EVP_MD *); | |
81 | if (md == NULL) | |
aacfb134 AG |
82 | return 0; |
83 | ||
5a285add | 84 | impl->md = md; |
aacfb134 AG |
85 | return 1; |
86 | ||
5a285add DM |
87 | case EVP_KDF_CTRL_SET_HKDF_MODE: |
88 | impl->mode = va_arg(args, int); | |
d2139cf8 MC |
89 | return 1; |
90 | ||
5a285add DM |
91 | case EVP_KDF_CTRL_SET_SALT: |
92 | p = va_arg(args, const unsigned char *); | |
93 | len = va_arg(args, size_t); | |
94 | if (len == 0 || p == NULL) | |
aacfb134 AG |
95 | return 1; |
96 | ||
5a285add DM |
97 | OPENSSL_free(impl->salt); |
98 | impl->salt = OPENSSL_memdup(p, len); | |
99 | if (impl->salt == NULL) | |
aacfb134 AG |
100 | return 0; |
101 | ||
5a285add | 102 | impl->salt_len = len; |
aacfb134 AG |
103 | return 1; |
104 | ||
5a285add DM |
105 | case EVP_KDF_CTRL_SET_KEY: |
106 | p = va_arg(args, const unsigned char *); | |
107 | len = va_arg(args, size_t); | |
108 | OPENSSL_clear_free(impl->key, impl->key_len); | |
109 | impl->key = OPENSSL_memdup(p, len); | |
110 | if (impl->key == NULL) | |
aacfb134 AG |
111 | return 0; |
112 | ||
5a285add DM |
113 | impl->key_len = len; |
114 | return 1; | |
aacfb134 | 115 | |
5a285add DM |
116 | case EVP_KDF_CTRL_RESET_HKDF_INFO: |
117 | OPENSSL_cleanse(impl->info, impl->info_len); | |
118 | impl->info_len = 0; | |
aacfb134 AG |
119 | return 1; |
120 | ||
5a285add DM |
121 | case EVP_KDF_CTRL_ADD_HKDF_INFO: |
122 | p = va_arg(args, const unsigned char *); | |
123 | len = va_arg(args, size_t); | |
124 | if (len == 0 || p == NULL) | |
aacfb134 AG |
125 | return 1; |
126 | ||
5a285add | 127 | if (len > (HKDF_MAXBUF - impl->info_len)) |
aacfb134 AG |
128 | return 0; |
129 | ||
5a285add DM |
130 | memcpy(impl->info + impl->info_len, p, len); |
131 | impl->info_len += len; | |
aacfb134 AG |
132 | return 1; |
133 | ||
134 | default: | |
135 | return -2; | |
aacfb134 AG |
136 | } |
137 | } | |
138 | ||
5a285add DM |
139 | static int kdf_hkdf_ctrl_str(EVP_KDF_IMPL *impl, const char *type, |
140 | const char *value) | |
aacfb134 | 141 | { |
ddd2c389 MC |
142 | if (strcmp(type, "mode") == 0) { |
143 | int mode; | |
144 | ||
145 | if (strcmp(value, "EXTRACT_AND_EXPAND") == 0) | |
5a285add | 146 | mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND; |
ddd2c389 | 147 | else if (strcmp(value, "EXTRACT_ONLY") == 0) |
5a285add | 148 | mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY; |
ddd2c389 | 149 | else if (strcmp(value, "EXPAND_ONLY") == 0) |
5a285add | 150 | mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY; |
ddd2c389 MC |
151 | else |
152 | return 0; | |
153 | ||
5a285add | 154 | return call_ctrl(kdf_hkdf_ctrl, impl, EVP_KDF_CTRL_SET_HKDF_MODE, mode); |
ddd2c389 MC |
155 | } |
156 | ||
5a285add DM |
157 | if (strcmp(type, "digest") == 0) |
158 | return kdf_md2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_MD, value); | |
aacfb134 AG |
159 | |
160 | if (strcmp(type, "salt") == 0) | |
5a285add | 161 | return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value); |
aacfb134 AG |
162 | |
163 | if (strcmp(type, "hexsalt") == 0) | |
5a285add | 164 | return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_SALT, value); |
aacfb134 AG |
165 | |
166 | if (strcmp(type, "key") == 0) | |
5a285add | 167 | return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value); |
aacfb134 AG |
168 | |
169 | if (strcmp(type, "hexkey") == 0) | |
5a285add | 170 | return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_SET_KEY, value); |
aacfb134 AG |
171 | |
172 | if (strcmp(type, "info") == 0) | |
5a285add DM |
173 | return kdf_str2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO, |
174 | value); | |
aacfb134 AG |
175 | |
176 | if (strcmp(type, "hexinfo") == 0) | |
5a285add DM |
177 | return kdf_hex2ctrl(impl, kdf_hkdf_ctrl, EVP_KDF_CTRL_ADD_HKDF_INFO, |
178 | value); | |
aacfb134 AG |
179 | |
180 | return -2; | |
181 | } | |
182 | ||
5a285add | 183 | static size_t kdf_hkdf_size(EVP_KDF_IMPL *impl) |
ca55d70b | 184 | { |
97cc9c9b SL |
185 | int sz; |
186 | ||
5a285add DM |
187 | if (impl->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY) |
188 | return SIZE_MAX; | |
ca55d70b | 189 | |
5a285add DM |
190 | if (impl->md == NULL) { |
191 | KDFerr(KDF_F_KDF_HKDF_SIZE, KDF_R_MISSING_MESSAGE_DIGEST); | |
192 | return 0; | |
193 | } | |
97cc9c9b SL |
194 | sz = EVP_MD_size(impl->md); |
195 | if (sz < 0) | |
196 | return 0; | |
197 | ||
198 | return sz; | |
ca55d70b MC |
199 | } |
200 | ||
5a285add DM |
201 | static int kdf_hkdf_derive(EVP_KDF_IMPL *impl, unsigned char *key, |
202 | size_t keylen) | |
aacfb134 | 203 | { |
5a285add DM |
204 | if (impl->md == NULL) { |
205 | KDFerr(KDF_F_KDF_HKDF_DERIVE, KDF_R_MISSING_MESSAGE_DIGEST); | |
f55129c7 JB |
206 | return 0; |
207 | } | |
5a285add DM |
208 | if (impl->key == NULL) { |
209 | KDFerr(KDF_F_KDF_HKDF_DERIVE, KDF_R_MISSING_KEY); | |
aacfb134 | 210 | return 0; |
e65f6509 | 211 | } |
aacfb134 | 212 | |
5a285add DM |
213 | switch (impl->mode) { |
214 | case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND: | |
215 | return HKDF(impl->md, impl->salt, impl->salt_len, impl->key, | |
216 | impl->key_len, impl->info, impl->info_len, key, | |
217 | keylen); | |
d2139cf8 | 218 | |
5a285add DM |
219 | case EVP_KDF_HKDF_MODE_EXTRACT_ONLY: |
220 | return HKDF_Extract(impl->md, impl->salt, impl->salt_len, impl->key, | |
221 | impl->key_len, key, keylen); | |
d2139cf8 | 222 | |
5a285add DM |
223 | case EVP_KDF_HKDF_MODE_EXPAND_ONLY: |
224 | return HKDF_Expand(impl->md, impl->key, impl->key_len, impl->info, | |
225 | impl->info_len, key, keylen); | |
d2139cf8 MC |
226 | |
227 | default: | |
aacfb134 AG |
228 | return 0; |
229 | } | |
aacfb134 AG |
230 | } |
231 | ||
d2ba8123 | 232 | const EVP_KDF hkdf_kdf_meth = { |
5a285add DM |
233 | EVP_KDF_HKDF, |
234 | kdf_hkdf_new, | |
235 | kdf_hkdf_free, | |
236 | kdf_hkdf_reset, | |
237 | kdf_hkdf_ctrl, | |
238 | kdf_hkdf_ctrl_str, | |
239 | kdf_hkdf_size, | |
240 | kdf_hkdf_derive | |
aacfb134 AG |
241 | }; |
242 | ||
e7018588 DM |
243 | /* |
244 | * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)" | |
245 | * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and | |
246 | * "Cryptographic Extraction and Key Derivation: The HKDF Scheme" | |
247 | * Section 4.2 (https://eprint.iacr.org/2010/264.pdf). | |
248 | * | |
249 | * From the paper: | |
250 | * The scheme HKDF is specified as: | |
251 | * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t) | |
252 | * | |
253 | * where: | |
254 | * SKM is source key material | |
255 | * XTS is extractor salt (which may be null or constant) | |
256 | * CTXinfo is context information (may be null) | |
257 | * L is the number of key bits to be produced by KDF | |
258 | * k is the output length in bits of the hash function used with HMAC | |
259 | * t = ceil(L/k) | |
260 | * the value K(t) is truncated to its first d = L mod k bits. | |
261 | * | |
262 | * From RFC 5869: | |
263 | * 2.2. Step 1: Extract | |
264 | * HKDF-Extract(salt, IKM) -> PRK | |
265 | * 2.3. Step 2: Expand | |
266 | * HKDF-Expand(PRK, info, L) -> OKM | |
267 | */ | |
5a285add DM |
268 | static int HKDF(const EVP_MD *evp_md, |
269 | const unsigned char *salt, size_t salt_len, | |
e7018588 | 270 | const unsigned char *ikm, size_t ikm_len, |
5a285add DM |
271 | const unsigned char *info, size_t info_len, |
272 | unsigned char *okm, size_t okm_len) | |
aacfb134 AG |
273 | { |
274 | unsigned char prk[EVP_MAX_MD_SIZE]; | |
97cc9c9b SL |
275 | int ret, sz; |
276 | size_t prk_len; | |
277 | ||
278 | sz = EVP_MD_size(evp_md); | |
279 | if (sz < 0) | |
280 | return 0; | |
281 | prk_len = (size_t)sz; | |
aacfb134 | 282 | |
e7018588 DM |
283 | /* Step 1: HKDF-Extract(salt, IKM) -> PRK */ |
284 | if (!HKDF_Extract(evp_md, salt, salt_len, ikm, ikm_len, prk, prk_len)) | |
5a285add | 285 | return 0; |
aacfb134 | 286 | |
e7018588 | 287 | /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */ |
d2139cf8 MC |
288 | ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len); |
289 | OPENSSL_cleanse(prk, sizeof(prk)); | |
290 | ||
291 | return ret; | |
aacfb134 AG |
292 | } |
293 | ||
e7018588 DM |
294 | /* |
295 | * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)" | |
296 | * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2). | |
297 | * | |
298 | * 2.2. Step 1: Extract | |
299 | * | |
300 | * HKDF-Extract(salt, IKM) -> PRK | |
301 | * | |
302 | * Options: | |
303 | * Hash a hash function; HashLen denotes the length of the | |
304 | * hash function output in octets | |
305 | * | |
306 | * Inputs: | |
307 | * salt optional salt value (a non-secret random value); | |
308 | * if not provided, it is set to a string of HashLen zeros. | |
309 | * IKM input keying material | |
310 | * | |
311 | * Output: | |
312 | * PRK a pseudorandom key (of HashLen octets) | |
313 | * | |
314 | * The output PRK is calculated as follows: | |
315 | * | |
316 | * PRK = HMAC-Hash(salt, IKM) | |
317 | */ | |
5a285add DM |
318 | static int HKDF_Extract(const EVP_MD *evp_md, |
319 | const unsigned char *salt, size_t salt_len, | |
e7018588 | 320 | const unsigned char *ikm, size_t ikm_len, |
5a285add | 321 | unsigned char *prk, size_t prk_len) |
aacfb134 | 322 | { |
97cc9c9b SL |
323 | int sz = EVP_MD_size(evp_md); |
324 | ||
325 | if (sz < 0) | |
326 | return 0; | |
327 | if (prk_len != (size_t)sz) { | |
5a285add DM |
328 | KDFerr(KDF_F_HKDF_EXTRACT, KDF_R_WRONG_OUTPUT_BUFFER_SIZE); |
329 | return 0; | |
330 | } | |
e7018588 DM |
331 | /* calc: PRK = HMAC-Hash(salt, IKM) */ |
332 | return HMAC(evp_md, salt, salt_len, ikm, ikm_len, prk, NULL) != NULL; | |
aacfb134 AG |
333 | } |
334 | ||
e7018588 DM |
335 | /* |
336 | * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)" | |
337 | * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3). | |
338 | * | |
339 | * 2.3. Step 2: Expand | |
340 | * | |
341 | * HKDF-Expand(PRK, info, L) -> OKM | |
342 | * | |
343 | * Options: | |
344 | * Hash a hash function; HashLen denotes the length of the | |
345 | * hash function output in octets | |
346 | * | |
347 | * Inputs: | |
348 | * PRK a pseudorandom key of at least HashLen octets | |
349 | * (usually, the output from the extract step) | |
350 | * info optional context and application specific information | |
351 | * (can be a zero-length string) | |
352 | * L length of output keying material in octets | |
353 | * (<= 255*HashLen) | |
354 | * | |
355 | * Output: | |
356 | * OKM output keying material (of L octets) | |
357 | * | |
358 | * The output OKM is calculated as follows: | |
359 | * | |
360 | * N = ceil(L/HashLen) | |
361 | * T = T(1) | T(2) | T(3) | ... | T(N) | |
362 | * OKM = first L octets of T | |
363 | * | |
364 | * where: | |
365 | * T(0) = empty string (zero length) | |
366 | * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01) | |
367 | * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02) | |
368 | * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03) | |
369 | * ... | |
370 | * | |
371 | * (where the constant concatenated to the end of each T(n) is a | |
372 | * single octet.) | |
373 | */ | |
5a285add DM |
374 | static int HKDF_Expand(const EVP_MD *evp_md, |
375 | const unsigned char *prk, size_t prk_len, | |
376 | const unsigned char *info, size_t info_len, | |
377 | unsigned char *okm, size_t okm_len) | |
aacfb134 AG |
378 | { |
379 | HMAC_CTX *hmac; | |
97cc9c9b | 380 | int ret = 0, sz; |
aacfb134 | 381 | unsigned int i; |
aacfb134 | 382 | unsigned char prev[EVP_MAX_MD_SIZE]; |
97cc9c9b SL |
383 | size_t done_len = 0, dig_len, n; |
384 | ||
385 | sz = EVP_MD_size(evp_md); | |
386 | if (sz <= 0) | |
387 | return 0; | |
388 | dig_len = (size_t)sz; | |
5a285add | 389 | |
e7018588 DM |
390 | /* calc: N = ceil(L/HashLen) */ |
391 | n = okm_len / dig_len; | |
aacfb134 AG |
392 | if (okm_len % dig_len) |
393 | n++; | |
394 | ||
d2139cf8 | 395 | if (n > 255 || okm == NULL) |
5a285add | 396 | return 0; |
aacfb134 AG |
397 | |
398 | if ((hmac = HMAC_CTX_new()) == NULL) | |
5a285add | 399 | return 0; |
aacfb134 AG |
400 | |
401 | if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL)) | |
402 | goto err; | |
403 | ||
404 | for (i = 1; i <= n; i++) { | |
405 | size_t copy_len; | |
406 | const unsigned char ctr = i; | |
407 | ||
e7018588 | 408 | /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */ |
aacfb134 AG |
409 | if (i > 1) { |
410 | if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL)) | |
411 | goto err; | |
412 | ||
413 | if (!HMAC_Update(hmac, prev, dig_len)) | |
414 | goto err; | |
415 | } | |
416 | ||
417 | if (!HMAC_Update(hmac, info, info_len)) | |
418 | goto err; | |
419 | ||
420 | if (!HMAC_Update(hmac, &ctr, 1)) | |
421 | goto err; | |
422 | ||
423 | if (!HMAC_Final(hmac, prev, NULL)) | |
424 | goto err; | |
425 | ||
426 | copy_len = (done_len + dig_len > okm_len) ? | |
427 | okm_len - done_len : | |
428 | dig_len; | |
429 | ||
430 | memcpy(okm + done_len, prev, copy_len); | |
431 | ||
432 | done_len += copy_len; | |
433 | } | |
5a285add | 434 | ret = 1; |
aacfb134 AG |
435 | |
436 | err: | |
64ed55ab | 437 | OPENSSL_cleanse(prev, sizeof(prev)); |
aacfb134 | 438 | HMAC_CTX_free(hmac); |
64ed55ab | 439 | return ret; |
aacfb134 | 440 | } |