2 * Copyright 2016-2021 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 <openssl/proverr.h>
24 #include "internal/cryptlib.h"
25 #include "internal/numbers.h"
26 #include "crypto/evp.h"
27 #include "prov/provider_ctx.h"
28 #include "prov/providercommon.h"
29 #include "prov/implementations.h"
30 #include "prov/provider_util.h"
33 #define HKDF_MAXBUF 2048
35 static OSSL_FUNC_kdf_newctx_fn kdf_hkdf_new;
36 static OSSL_FUNC_kdf_freectx_fn kdf_hkdf_free;
37 static OSSL_FUNC_kdf_reset_fn kdf_hkdf_reset;
38 static OSSL_FUNC_kdf_derive_fn kdf_hkdf_derive;
39 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_hkdf_settable_ctx_params;
40 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_hkdf_set_ctx_params;
41 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_hkdf_gettable_ctx_params;
42 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_hkdf_get_ctx_params;
44 static int HKDF(OSSL_LIB_CTX *libctx, const EVP_MD *evp_md,
45 const unsigned char *salt, size_t salt_len,
46 const unsigned char *key, size_t key_len,
47 const unsigned char *info, size_t info_len,
48 unsigned char *okm, size_t okm_len);
49 static int HKDF_Extract(OSSL_LIB_CTX *libctx, const EVP_MD *evp_md,
50 const unsigned char *salt, size_t salt_len,
51 const unsigned char *ikm, size_t ikm_len,
52 unsigned char *prk, size_t prk_len);
53 static int HKDF_Expand(const EVP_MD *evp_md,
54 const unsigned char *prk, size_t prk_len,
55 const unsigned char *info, size_t info_len,
56 unsigned char *okm, size_t okm_len);
66 unsigned char info[HKDF_MAXBUF];
70 static void *kdf_hkdf_new(void *provctx)
74 if (!ossl_prov_is_running())
77 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
78 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
80 ctx->provctx = provctx;
84 static void kdf_hkdf_free(void *vctx)
86 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
94 static void kdf_hkdf_reset(void *vctx)
96 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
97 void *provctx = ctx->provctx;
99 ossl_prov_digest_reset(&ctx->digest);
100 OPENSSL_free(ctx->salt);
101 OPENSSL_clear_free(ctx->key, ctx->key_len);
102 OPENSSL_cleanse(ctx->info, ctx->info_len);
103 memset(ctx, 0, sizeof(*ctx));
104 ctx->provctx = provctx;
107 static size_t kdf_hkdf_size(KDF_HKDF *ctx)
110 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
112 if (ctx->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY)
116 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
119 sz = EVP_MD_get_size(md);
126 static int kdf_hkdf_derive(void *vctx, unsigned char *key, size_t keylen,
127 const OSSL_PARAM params[])
129 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
130 OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
133 if (!ossl_prov_is_running() || !kdf_hkdf_set_ctx_params(ctx, params))
136 md = ossl_prov_digest_md(&ctx->digest);
138 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
141 if (ctx->key == NULL) {
142 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
146 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
151 case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
153 return HKDF(libctx, md, ctx->salt, ctx->salt_len,
154 ctx->key, ctx->key_len, ctx->info, ctx->info_len, key, keylen);
156 case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
157 return HKDF_Extract(libctx, md, ctx->salt, ctx->salt_len,
158 ctx->key, ctx->key_len, key, keylen);
160 case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
161 return HKDF_Expand(md, ctx->key, ctx->key_len, ctx->info,
162 ctx->info_len, key, keylen);
166 static int kdf_hkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
169 KDF_HKDF *ctx = vctx;
170 OSSL_LIB_CTX *libctx = PROV_LIBCTX_OF(ctx->provctx);
176 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, libctx))
179 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE)) != NULL) {
180 if (p->data_type == OSSL_PARAM_UTF8_STRING) {
181 if (strcasecmp(p->data, "EXTRACT_AND_EXPAND") == 0) {
182 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
183 } else if (strcasecmp(p->data, "EXTRACT_ONLY") == 0) {
184 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
185 } else if (strcasecmp(p->data, "EXPAND_ONLY") == 0) {
186 ctx->mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
188 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
191 } else if (OSSL_PARAM_get_int(p, &n)) {
192 if (n != EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND
193 && n != EVP_KDF_HKDF_MODE_EXTRACT_ONLY
194 && n != EVP_KDF_HKDF_MODE_EXPAND_ONLY) {
195 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
200 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
205 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) {
206 OPENSSL_clear_free(ctx->key, ctx->key_len);
208 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->key, 0,
213 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL) {
214 if (p->data_size != 0 && p->data != NULL) {
215 OPENSSL_free(ctx->salt);
217 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->salt, 0,
222 /* The info fields concatenate, so process them all */
223 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL) {
225 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
226 OSSL_KDF_PARAM_INFO)) {
227 const void *q = ctx->info + ctx->info_len;
230 if (p->data_size != 0
232 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
233 HKDF_MAXBUF - ctx->info_len,
242 static const OSSL_PARAM *kdf_hkdf_settable_ctx_params(ossl_unused void *ctx,
243 ossl_unused void *provctx)
245 static const OSSL_PARAM known_settable_ctx_params[] = {
246 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
247 OSSL_PARAM_int(OSSL_KDF_PARAM_MODE, NULL),
248 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
249 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
250 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
251 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
252 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
255 return known_settable_ctx_params;
258 static int kdf_hkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
260 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
263 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL) {
264 size_t sz = kdf_hkdf_size(ctx);
268 return OSSL_PARAM_set_size_t(p, sz);
273 static const OSSL_PARAM *kdf_hkdf_gettable_ctx_params(ossl_unused void *ctx,
274 ossl_unused void *provctx)
276 static const OSSL_PARAM known_gettable_ctx_params[] = {
277 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
280 return known_gettable_ctx_params;
283 const OSSL_DISPATCH ossl_kdf_hkdf_functions[] = {
284 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_hkdf_new },
285 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_hkdf_free },
286 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_hkdf_reset },
287 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_hkdf_derive },
288 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
289 (void(*)(void))kdf_hkdf_settable_ctx_params },
290 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_hkdf_set_ctx_params },
291 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
292 (void(*)(void))kdf_hkdf_gettable_ctx_params },
293 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_hkdf_get_ctx_params },
298 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
299 * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and
300 * "Cryptographic Extraction and Key Derivation: The HKDF Scheme"
301 * Section 4.2 (https://eprint.iacr.org/2010/264.pdf).
304 * The scheme HKDF is specified as:
305 * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t)
308 * SKM is source key material
309 * XTS is extractor salt (which may be null or constant)
310 * CTXinfo is context information (may be null)
311 * L is the number of key bits to be produced by KDF
312 * k is the output length in bits of the hash function used with HMAC
314 * the value K(t) is truncated to its first d = L mod k bits.
317 * 2.2. Step 1: Extract
318 * HKDF-Extract(salt, IKM) -> PRK
319 * 2.3. Step 2: Expand
320 * HKDF-Expand(PRK, info, L) -> OKM
322 static int HKDF(OSSL_LIB_CTX *libctx, const EVP_MD *evp_md,
323 const unsigned char *salt, size_t salt_len,
324 const unsigned char *ikm, size_t ikm_len,
325 const unsigned char *info, size_t info_len,
326 unsigned char *okm, size_t okm_len)
328 unsigned char prk[EVP_MAX_MD_SIZE];
332 sz = EVP_MD_get_size(evp_md);
335 prk_len = (size_t)sz;
337 /* Step 1: HKDF-Extract(salt, IKM) -> PRK */
338 if (!HKDF_Extract(libctx, evp_md,
339 salt, salt_len, ikm, ikm_len, prk, prk_len))
342 /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */
343 ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
344 OPENSSL_cleanse(prk, sizeof(prk));
350 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
351 * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2).
353 * 2.2. Step 1: Extract
355 * HKDF-Extract(salt, IKM) -> PRK
358 * Hash a hash function; HashLen denotes the length of the
359 * hash function output in octets
362 * salt optional salt value (a non-secret random value);
363 * if not provided, it is set to a string of HashLen zeros.
364 * IKM input keying material
367 * PRK a pseudorandom key (of HashLen octets)
369 * The output PRK is calculated as follows:
371 * PRK = HMAC-Hash(salt, IKM)
373 static int HKDF_Extract(OSSL_LIB_CTX *libctx, const EVP_MD *evp_md,
374 const unsigned char *salt, size_t salt_len,
375 const unsigned char *ikm, size_t ikm_len,
376 unsigned char *prk, size_t prk_len)
378 int sz = EVP_MD_get_size(evp_md);
382 if (prk_len != (size_t)sz) {
383 ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
386 /* calc: PRK = HMAC-Hash(salt, IKM) */
388 EVP_Q_mac(libctx, "HMAC", NULL, EVP_MD_get0_name(evp_md), NULL, salt,
389 salt_len, ikm, ikm_len, prk, EVP_MD_get_size(evp_md), NULL)
394 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
395 * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3).
397 * 2.3. Step 2: Expand
399 * HKDF-Expand(PRK, info, L) -> OKM
402 * Hash a hash function; HashLen denotes the length of the
403 * hash function output in octets
406 * PRK a pseudorandom key of at least HashLen octets
407 * (usually, the output from the extract step)
408 * info optional context and application specific information
409 * (can be a zero-length string)
410 * L length of output keying material in octets
414 * OKM output keying material (of L octets)
416 * The output OKM is calculated as follows:
418 * N = ceil(L/HashLen)
419 * T = T(1) | T(2) | T(3) | ... | T(N)
420 * OKM = first L octets of T
423 * T(0) = empty string (zero length)
424 * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
425 * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02)
426 * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03)
429 * (where the constant concatenated to the end of each T(n) is a
432 static int HKDF_Expand(const EVP_MD *evp_md,
433 const unsigned char *prk, size_t prk_len,
434 const unsigned char *info, size_t info_len,
435 unsigned char *okm, size_t okm_len)
440 unsigned char prev[EVP_MAX_MD_SIZE];
441 size_t done_len = 0, dig_len, n;
443 sz = EVP_MD_get_size(evp_md);
446 dig_len = (size_t)sz;
448 /* calc: N = ceil(L/HashLen) */
449 n = okm_len / dig_len;
450 if (okm_len % dig_len)
453 if (n > 255 || okm == NULL)
456 if ((hmac = HMAC_CTX_new()) == NULL)
459 if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
462 for (i = 1; i <= n; i++) {
464 const unsigned char ctr = i;
466 /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */
468 if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
471 if (!HMAC_Update(hmac, prev, dig_len))
475 if (!HMAC_Update(hmac, info, info_len))
478 if (!HMAC_Update(hmac, &ctr, 1))
481 if (!HMAC_Final(hmac, prev, NULL))
484 copy_len = (done_len + dig_len > okm_len) ?
488 memcpy(okm + done_len, prev, copy_len);
490 done_len += copy_len;
495 OPENSSL_cleanse(prev, sizeof(prev));