2 * Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.
4 * Licensed under the Apache License 2.0 (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
11 * HMAC low level APIs are deprecated for public use, but still ok for internal
14 #include "internal/deprecated.h"
19 #include <openssl/hmac.h>
20 #include <openssl/evp.h>
21 #include <openssl/kdf.h>
22 #include <openssl/core_names.h>
23 #include "internal/cryptlib.h"
24 #include "internal/numbers.h"
25 #include "crypto/evp.h"
26 #include "prov/provider_ctx.h"
27 #include "prov/providercommonerr.h"
28 #include "prov/implementations.h"
29 #include "prov/provider_util.h"
32 #define HKDF_MAXBUF 1024
34 static OSSL_FUNC_kdf_newctx_fn kdf_hkdf_new;
35 static OSSL_FUNC_kdf_freectx_fn kdf_hkdf_free;
36 static OSSL_FUNC_kdf_reset_fn kdf_hkdf_reset;
37 static OSSL_FUNC_kdf_derive_fn kdf_hkdf_derive;
38 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_hkdf_settable_ctx_params;
39 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_hkdf_set_ctx_params;
40 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_hkdf_gettable_ctx_params;
41 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_hkdf_get_ctx_params;
43 static int HKDF(const EVP_MD *evp_md,
44 const unsigned char *salt, size_t salt_len,
45 const unsigned char *key, size_t key_len,
46 const unsigned char *info, size_t info_len,
47 unsigned char *okm, size_t okm_len);
48 static int HKDF_Extract(const EVP_MD *evp_md,
49 const unsigned char *salt, size_t salt_len,
50 const unsigned char *ikm, size_t ikm_len,
51 unsigned char *prk, size_t prk_len);
52 static int HKDF_Expand(const EVP_MD *evp_md,
53 const unsigned char *prk, size_t prk_len,
54 const unsigned char *info, size_t info_len,
55 unsigned char *okm, size_t okm_len);
65 unsigned char info[HKDF_MAXBUF];
69 static void *kdf_hkdf_new(void *provctx)
73 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
74 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
76 ctx->provctx = provctx;
80 static void kdf_hkdf_free(void *vctx)
82 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
90 static void kdf_hkdf_reset(void *vctx)
92 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
93 void *provctx = ctx->provctx;
95 ossl_prov_digest_reset(&ctx->digest);
96 OPENSSL_free(ctx->salt);
97 OPENSSL_clear_free(ctx->key, ctx->key_len);
98 OPENSSL_cleanse(ctx->info, ctx->info_len);
99 memset(ctx, 0, sizeof(*ctx));
100 ctx->provctx = provctx;
103 static size_t kdf_hkdf_size(KDF_HKDF *ctx)
106 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
108 if (ctx->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY)
112 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
115 sz = EVP_MD_size(md);
122 static int kdf_hkdf_derive(void *vctx, unsigned char *key, size_t keylen)
124 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
125 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
128 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
131 if (ctx->key == NULL) {
132 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
137 case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
138 return HKDF(md, ctx->salt, ctx->salt_len, ctx->key,
139 ctx->key_len, ctx->info, ctx->info_len, key,
142 case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
143 return HKDF_Extract(md, ctx->salt, ctx->salt_len, ctx->key,
144 ctx->key_len, key, keylen);
146 case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
147 return HKDF_Expand(md, ctx->key, ctx->key_len, ctx->info,
148 ctx->info_len, key, keylen);
155 static int kdf_hkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
158 KDF_HKDF *ctx = vctx;
159 OPENSSL_CTX *provctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
162 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
165 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE)) != NULL) {
166 if (p->data_type == OSSL_PARAM_UTF8_STRING) {
167 if (strcasecmp(p->data, "EXTRACT_AND_EXPAND") == 0) {
168 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
169 } else if (strcasecmp(p->data, "EXTRACT_ONLY") == 0) {
170 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
171 } else if (strcasecmp(p->data, "EXPAND_ONLY") == 0) {
172 ctx->mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
174 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
177 } else if (OSSL_PARAM_get_int(p, &n)) {
178 if (n != EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND
179 && n != EVP_KDF_HKDF_MODE_EXTRACT_ONLY
180 && n != EVP_KDF_HKDF_MODE_EXPAND_ONLY) {
181 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
186 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
191 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) {
192 OPENSSL_clear_free(ctx->key, ctx->key_len);
194 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->key, 0,
199 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL) {
200 if (p->data_size != 0 && p->data != NULL) {
201 OPENSSL_free(ctx->salt);
203 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->salt, 0,
208 /* The info fields concatenate, so process them all */
209 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL) {
211 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
212 OSSL_KDF_PARAM_INFO)) {
213 const void *q = ctx->info + ctx->info_len;
216 if (p->data_size != 0
218 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
219 HKDF_MAXBUF - ctx->info_len,
228 static const OSSL_PARAM *kdf_hkdf_settable_ctx_params(ossl_unused void *provctx)
230 static const OSSL_PARAM known_settable_ctx_params[] = {
231 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
232 OSSL_PARAM_int(OSSL_KDF_PARAM_MODE, NULL),
233 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
234 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
235 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
236 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
237 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
240 return known_settable_ctx_params;
243 static int kdf_hkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
245 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
248 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
249 return OSSL_PARAM_set_size_t(p, kdf_hkdf_size(ctx));
253 static const OSSL_PARAM *kdf_hkdf_gettable_ctx_params(ossl_unused void *provctx)
255 static const OSSL_PARAM known_gettable_ctx_params[] = {
256 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
259 return known_gettable_ctx_params;
262 const OSSL_DISPATCH kdf_hkdf_functions[] = {
263 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_hkdf_new },
264 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_hkdf_free },
265 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_hkdf_reset },
266 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_hkdf_derive },
267 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
268 (void(*)(void))kdf_hkdf_settable_ctx_params },
269 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_hkdf_set_ctx_params },
270 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
271 (void(*)(void))kdf_hkdf_gettable_ctx_params },
272 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_hkdf_get_ctx_params },
277 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
278 * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and
279 * "Cryptographic Extraction and Key Derivation: The HKDF Scheme"
280 * Section 4.2 (https://eprint.iacr.org/2010/264.pdf).
283 * The scheme HKDF is specified as:
284 * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t)
287 * SKM is source key material
288 * XTS is extractor salt (which may be null or constant)
289 * CTXinfo is context information (may be null)
290 * L is the number of key bits to be produced by KDF
291 * k is the output length in bits of the hash function used with HMAC
293 * the value K(t) is truncated to its first d = L mod k bits.
296 * 2.2. Step 1: Extract
297 * HKDF-Extract(salt, IKM) -> PRK
298 * 2.3. Step 2: Expand
299 * HKDF-Expand(PRK, info, L) -> OKM
301 static int HKDF(const EVP_MD *evp_md,
302 const unsigned char *salt, size_t salt_len,
303 const unsigned char *ikm, size_t ikm_len,
304 const unsigned char *info, size_t info_len,
305 unsigned char *okm, size_t okm_len)
307 unsigned char prk[EVP_MAX_MD_SIZE];
311 sz = EVP_MD_size(evp_md);
314 prk_len = (size_t)sz;
316 /* Step 1: HKDF-Extract(salt, IKM) -> PRK */
317 if (!HKDF_Extract(evp_md, salt, salt_len, ikm, ikm_len, prk, prk_len))
320 /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */
321 ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
322 OPENSSL_cleanse(prk, sizeof(prk));
328 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
329 * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2).
331 * 2.2. Step 1: Extract
333 * HKDF-Extract(salt, IKM) -> PRK
336 * Hash a hash function; HashLen denotes the length of the
337 * hash function output in octets
340 * salt optional salt value (a non-secret random value);
341 * if not provided, it is set to a string of HashLen zeros.
342 * IKM input keying material
345 * PRK a pseudorandom key (of HashLen octets)
347 * The output PRK is calculated as follows:
349 * PRK = HMAC-Hash(salt, IKM)
351 static int HKDF_Extract(const EVP_MD *evp_md,
352 const unsigned char *salt, size_t salt_len,
353 const unsigned char *ikm, size_t ikm_len,
354 unsigned char *prk, size_t prk_len)
356 int sz = EVP_MD_size(evp_md);
360 if (prk_len != (size_t)sz) {
361 ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
364 /* calc: PRK = HMAC-Hash(salt, IKM) */
365 return HMAC(evp_md, salt, salt_len, ikm, ikm_len, prk, NULL) != NULL;
369 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
370 * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3).
372 * 2.3. Step 2: Expand
374 * HKDF-Expand(PRK, info, L) -> OKM
377 * Hash a hash function; HashLen denotes the length of the
378 * hash function output in octets
381 * PRK a pseudorandom key of at least HashLen octets
382 * (usually, the output from the extract step)
383 * info optional context and application specific information
384 * (can be a zero-length string)
385 * L length of output keying material in octets
389 * OKM output keying material (of L octets)
391 * The output OKM is calculated as follows:
393 * N = ceil(L/HashLen)
394 * T = T(1) | T(2) | T(3) | ... | T(N)
395 * OKM = first L octets of T
398 * T(0) = empty string (zero length)
399 * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
400 * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02)
401 * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03)
404 * (where the constant concatenated to the end of each T(n) is a
407 static int HKDF_Expand(const EVP_MD *evp_md,
408 const unsigned char *prk, size_t prk_len,
409 const unsigned char *info, size_t info_len,
410 unsigned char *okm, size_t okm_len)
415 unsigned char prev[EVP_MAX_MD_SIZE];
416 size_t done_len = 0, dig_len, n;
418 sz = EVP_MD_size(evp_md);
421 dig_len = (size_t)sz;
423 /* calc: N = ceil(L/HashLen) */
424 n = okm_len / dig_len;
425 if (okm_len % dig_len)
428 if (n > 255 || okm == NULL)
431 if ((hmac = HMAC_CTX_new()) == NULL)
434 if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
437 for (i = 1; i <= n; i++) {
439 const unsigned char ctr = i;
441 /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */
443 if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
446 if (!HMAC_Update(hmac, prev, dig_len))
450 if (!HMAC_Update(hmac, info, info_len))
453 if (!HMAC_Update(hmac, &ctr, 1))
456 if (!HMAC_Final(hmac, prev, NULL))
459 copy_len = (done_len + dig_len > okm_len) ?
463 memcpy(okm + done_len, prev, copy_len);
465 done_len += copy_len;
470 OPENSSL_cleanse(prev, sizeof(prev));