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_OP_kdf_newctx_fn kdf_hkdf_new;
35 static OSSL_OP_kdf_freectx_fn kdf_hkdf_free;
36 static OSSL_OP_kdf_reset_fn kdf_hkdf_reset;
37 static OSSL_OP_kdf_derive_fn kdf_hkdf_derive;
38 static OSSL_OP_kdf_settable_ctx_params_fn kdf_hkdf_settable_ctx_params;
39 static OSSL_OP_kdf_set_ctx_params_fn kdf_hkdf_set_ctx_params;
40 static OSSL_OP_kdf_gettable_ctx_params_fn kdf_hkdf_gettable_ctx_params;
41 static OSSL_OP_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;
94 ossl_prov_digest_reset(&ctx->digest);
95 OPENSSL_free(ctx->salt);
96 OPENSSL_clear_free(ctx->key, ctx->key_len);
97 OPENSSL_cleanse(ctx->info, ctx->info_len);
98 memset(ctx, 0, sizeof(*ctx));
101 static size_t kdf_hkdf_size(KDF_HKDF *ctx)
104 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
106 if (ctx->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY)
110 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
113 sz = EVP_MD_size(md);
120 static int kdf_hkdf_derive(void *vctx, unsigned char *key, size_t keylen)
122 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
123 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
126 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
129 if (ctx->key == NULL) {
130 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
135 case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
136 return HKDF(md, ctx->salt, ctx->salt_len, ctx->key,
137 ctx->key_len, ctx->info, ctx->info_len, key,
140 case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
141 return HKDF_Extract(md, ctx->salt, ctx->salt_len, ctx->key,
142 ctx->key_len, key, keylen);
144 case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
145 return HKDF_Expand(md, ctx->key, ctx->key_len, ctx->info,
146 ctx->info_len, key, keylen);
153 static int kdf_hkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
156 KDF_HKDF *ctx = vctx;
157 OPENSSL_CTX *provctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
160 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
163 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE)) != NULL) {
164 if (p->data_type == OSSL_PARAM_UTF8_STRING) {
165 if (strcasecmp(p->data, "EXTRACT_AND_EXPAND") == 0) {
166 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
167 } else if (strcasecmp(p->data, "EXTRACT_ONLY") == 0) {
168 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
169 } else if (strcasecmp(p->data, "EXPAND_ONLY") == 0) {
170 ctx->mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
172 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
175 } else if (OSSL_PARAM_get_int(p, &n)) {
176 if (n != EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND
177 && n != EVP_KDF_HKDF_MODE_EXTRACT_ONLY
178 && n != EVP_KDF_HKDF_MODE_EXPAND_ONLY) {
179 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
184 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
189 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) {
190 OPENSSL_clear_free(ctx->key, ctx->key_len);
192 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->key, 0,
197 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL) {
198 if (p->data_size != 0 && p->data != NULL) {
199 OPENSSL_free(ctx->salt);
201 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->salt, 0,
206 /* The info fields concatenate, so process them all */
207 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL) {
209 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
210 OSSL_KDF_PARAM_INFO)) {
211 const void *q = ctx->info + ctx->info_len;
214 if (p->data_size != 0
216 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
217 HKDF_MAXBUF - ctx->info_len,
226 static const OSSL_PARAM *kdf_hkdf_settable_ctx_params(void)
228 static const OSSL_PARAM known_settable_ctx_params[] = {
229 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
230 OSSL_PARAM_int(OSSL_KDF_PARAM_MODE, NULL),
231 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
232 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
233 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
234 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
235 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
238 return known_settable_ctx_params;
241 static int kdf_hkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
243 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
246 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
247 return OSSL_PARAM_set_size_t(p, kdf_hkdf_size(ctx));
251 static const OSSL_PARAM *kdf_hkdf_gettable_ctx_params(void)
253 static const OSSL_PARAM known_gettable_ctx_params[] = {
254 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
257 return known_gettable_ctx_params;
260 const OSSL_DISPATCH kdf_hkdf_functions[] = {
261 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_hkdf_new },
262 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_hkdf_free },
263 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_hkdf_reset },
264 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_hkdf_derive },
265 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
266 (void(*)(void))kdf_hkdf_settable_ctx_params },
267 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_hkdf_set_ctx_params },
268 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
269 (void(*)(void))kdf_hkdf_gettable_ctx_params },
270 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_hkdf_get_ctx_params },
275 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
276 * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and
277 * "Cryptographic Extraction and Key Derivation: The HKDF Scheme"
278 * Section 4.2 (https://eprint.iacr.org/2010/264.pdf).
281 * The scheme HKDF is specified as:
282 * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t)
285 * SKM is source key material
286 * XTS is extractor salt (which may be null or constant)
287 * CTXinfo is context information (may be null)
288 * L is the number of key bits to be produced by KDF
289 * k is the output length in bits of the hash function used with HMAC
291 * the value K(t) is truncated to its first d = L mod k bits.
294 * 2.2. Step 1: Extract
295 * HKDF-Extract(salt, IKM) -> PRK
296 * 2.3. Step 2: Expand
297 * HKDF-Expand(PRK, info, L) -> OKM
299 static int HKDF(const EVP_MD *evp_md,
300 const unsigned char *salt, size_t salt_len,
301 const unsigned char *ikm, size_t ikm_len,
302 const unsigned char *info, size_t info_len,
303 unsigned char *okm, size_t okm_len)
305 unsigned char prk[EVP_MAX_MD_SIZE];
309 sz = EVP_MD_size(evp_md);
312 prk_len = (size_t)sz;
314 /* Step 1: HKDF-Extract(salt, IKM) -> PRK */
315 if (!HKDF_Extract(evp_md, salt, salt_len, ikm, ikm_len, prk, prk_len))
318 /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */
319 ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
320 OPENSSL_cleanse(prk, sizeof(prk));
326 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
327 * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2).
329 * 2.2. Step 1: Extract
331 * HKDF-Extract(salt, IKM) -> PRK
334 * Hash a hash function; HashLen denotes the length of the
335 * hash function output in octets
338 * salt optional salt value (a non-secret random value);
339 * if not provided, it is set to a string of HashLen zeros.
340 * IKM input keying material
343 * PRK a pseudorandom key (of HashLen octets)
345 * The output PRK is calculated as follows:
347 * PRK = HMAC-Hash(salt, IKM)
349 static int HKDF_Extract(const EVP_MD *evp_md,
350 const unsigned char *salt, size_t salt_len,
351 const unsigned char *ikm, size_t ikm_len,
352 unsigned char *prk, size_t prk_len)
354 int sz = EVP_MD_size(evp_md);
358 if (prk_len != (size_t)sz) {
359 ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
362 /* calc: PRK = HMAC-Hash(salt, IKM) */
363 return HMAC(evp_md, salt, salt_len, ikm, ikm_len, prk, NULL) != NULL;
367 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
368 * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3).
370 * 2.3. Step 2: Expand
372 * HKDF-Expand(PRK, info, L) -> OKM
375 * Hash a hash function; HashLen denotes the length of the
376 * hash function output in octets
379 * PRK a pseudorandom key of at least HashLen octets
380 * (usually, the output from the extract step)
381 * info optional context and application specific information
382 * (can be a zero-length string)
383 * L length of output keying material in octets
387 * OKM output keying material (of L octets)
389 * The output OKM is calculated as follows:
391 * N = ceil(L/HashLen)
392 * T = T(1) | T(2) | T(3) | ... | T(N)
393 * OKM = first L octets of T
396 * T(0) = empty string (zero length)
397 * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
398 * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02)
399 * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03)
402 * (where the constant concatenated to the end of each T(n) is a
405 static int HKDF_Expand(const EVP_MD *evp_md,
406 const unsigned char *prk, size_t prk_len,
407 const unsigned char *info, size_t info_len,
408 unsigned char *okm, size_t okm_len)
413 unsigned char prev[EVP_MAX_MD_SIZE];
414 size_t done_len = 0, dig_len, n;
416 sz = EVP_MD_size(evp_md);
419 dig_len = (size_t)sz;
421 /* calc: N = ceil(L/HashLen) */
422 n = okm_len / dig_len;
423 if (okm_len % dig_len)
426 if (n > 255 || okm == NULL)
429 if ((hmac = HMAC_CTX_new()) == NULL)
432 if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
435 for (i = 1; i <= n; i++) {
437 const unsigned char ctr = i;
439 /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */
441 if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
444 if (!HMAC_Update(hmac, prev, dig_len))
448 if (!HMAC_Update(hmac, info, info_len))
451 if (!HMAC_Update(hmac, &ctr, 1))
454 if (!HMAC_Final(hmac, prev, NULL))
457 copy_len = (done_len + dig_len > okm_len) ?
461 memcpy(okm + done_len, prev, copy_len);
463 done_len += copy_len;
468 OPENSSL_cleanse(prev, sizeof(prev));