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 1024
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(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(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_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;
132 if (!ossl_prov_is_running() || !kdf_hkdf_set_ctx_params(ctx, params))
135 md = ossl_prov_digest_md(&ctx->digest);
137 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
140 if (ctx->key == NULL) {
141 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
145 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_KEY_LENGTH);
150 case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
151 return HKDF(md, ctx->salt, ctx->salt_len, ctx->key,
152 ctx->key_len, ctx->info, ctx->info_len, key,
155 case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
156 return HKDF_Extract(md, ctx->salt, ctx->salt_len, ctx->key,
157 ctx->key_len, key, keylen);
159 case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
160 return HKDF_Expand(md, ctx->key, ctx->key_len, ctx->info,
161 ctx->info_len, key, keylen);
168 static int kdf_hkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
171 KDF_HKDF *ctx = vctx;
172 OSSL_LIB_CTX *provctx = PROV_LIBCTX_OF(ctx->provctx);
175 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
178 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE)) != NULL) {
179 if (p->data_type == OSSL_PARAM_UTF8_STRING) {
180 if (strcasecmp(p->data, "EXTRACT_AND_EXPAND") == 0) {
181 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
182 } else if (strcasecmp(p->data, "EXTRACT_ONLY") == 0) {
183 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
184 } else if (strcasecmp(p->data, "EXPAND_ONLY") == 0) {
185 ctx->mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
187 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
190 } else if (OSSL_PARAM_get_int(p, &n)) {
191 if (n != EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND
192 && n != EVP_KDF_HKDF_MODE_EXTRACT_ONLY
193 && n != EVP_KDF_HKDF_MODE_EXPAND_ONLY) {
194 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
199 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
204 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) {
205 OPENSSL_clear_free(ctx->key, ctx->key_len);
207 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->key, 0,
212 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL) {
213 if (p->data_size != 0 && p->data != NULL) {
214 OPENSSL_free(ctx->salt);
216 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->salt, 0,
221 /* The info fields concatenate, so process them all */
222 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL) {
224 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
225 OSSL_KDF_PARAM_INFO)) {
226 const void *q = ctx->info + ctx->info_len;
229 if (p->data_size != 0
231 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
232 HKDF_MAXBUF - ctx->info_len,
241 static const OSSL_PARAM *kdf_hkdf_settable_ctx_params(ossl_unused void *ctx,
242 ossl_unused void *provctx)
244 static const OSSL_PARAM known_settable_ctx_params[] = {
245 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
246 OSSL_PARAM_int(OSSL_KDF_PARAM_MODE, NULL),
247 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
248 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
249 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
250 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
251 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
254 return known_settable_ctx_params;
257 static int kdf_hkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
259 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
262 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
263 return OSSL_PARAM_set_size_t(p, kdf_hkdf_size(ctx));
267 static const OSSL_PARAM *kdf_hkdf_gettable_ctx_params(ossl_unused void *ctx,
268 ossl_unused void *provctx)
270 static const OSSL_PARAM known_gettable_ctx_params[] = {
271 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
274 return known_gettable_ctx_params;
277 const OSSL_DISPATCH ossl_kdf_hkdf_functions[] = {
278 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_hkdf_new },
279 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_hkdf_free },
280 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_hkdf_reset },
281 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_hkdf_derive },
282 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
283 (void(*)(void))kdf_hkdf_settable_ctx_params },
284 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_hkdf_set_ctx_params },
285 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
286 (void(*)(void))kdf_hkdf_gettable_ctx_params },
287 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_hkdf_get_ctx_params },
292 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
293 * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and
294 * "Cryptographic Extraction and Key Derivation: The HKDF Scheme"
295 * Section 4.2 (https://eprint.iacr.org/2010/264.pdf).
298 * The scheme HKDF is specified as:
299 * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t)
302 * SKM is source key material
303 * XTS is extractor salt (which may be null or constant)
304 * CTXinfo is context information (may be null)
305 * L is the number of key bits to be produced by KDF
306 * k is the output length in bits of the hash function used with HMAC
308 * the value K(t) is truncated to its first d = L mod k bits.
311 * 2.2. Step 1: Extract
312 * HKDF-Extract(salt, IKM) -> PRK
313 * 2.3. Step 2: Expand
314 * HKDF-Expand(PRK, info, L) -> OKM
316 static int HKDF(const EVP_MD *evp_md,
317 const unsigned char *salt, size_t salt_len,
318 const unsigned char *ikm, size_t ikm_len,
319 const unsigned char *info, size_t info_len,
320 unsigned char *okm, size_t okm_len)
322 unsigned char prk[EVP_MAX_MD_SIZE];
326 sz = EVP_MD_size(evp_md);
329 prk_len = (size_t)sz;
331 /* Step 1: HKDF-Extract(salt, IKM) -> PRK */
332 if (!HKDF_Extract(evp_md, salt, salt_len, ikm, ikm_len, prk, prk_len))
335 /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */
336 ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
337 OPENSSL_cleanse(prk, sizeof(prk));
343 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
344 * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2).
346 * 2.2. Step 1: Extract
348 * HKDF-Extract(salt, IKM) -> PRK
351 * Hash a hash function; HashLen denotes the length of the
352 * hash function output in octets
355 * salt optional salt value (a non-secret random value);
356 * if not provided, it is set to a string of HashLen zeros.
357 * IKM input keying material
360 * PRK a pseudorandom key (of HashLen octets)
362 * The output PRK is calculated as follows:
364 * PRK = HMAC-Hash(salt, IKM)
366 static int HKDF_Extract(const EVP_MD *evp_md,
367 const unsigned char *salt, size_t salt_len,
368 const unsigned char *ikm, size_t ikm_len,
369 unsigned char *prk, size_t prk_len)
371 int sz = EVP_MD_size(evp_md);
375 if (prk_len != (size_t)sz) {
376 ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
379 /* calc: PRK = HMAC-Hash(salt, IKM) */
380 return HMAC(evp_md, salt, salt_len, ikm, ikm_len, prk, NULL) != NULL;
384 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
385 * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3).
387 * 2.3. Step 2: Expand
389 * HKDF-Expand(PRK, info, L) -> OKM
392 * Hash a hash function; HashLen denotes the length of the
393 * hash function output in octets
396 * PRK a pseudorandom key of at least HashLen octets
397 * (usually, the output from the extract step)
398 * info optional context and application specific information
399 * (can be a zero-length string)
400 * L length of output keying material in octets
404 * OKM output keying material (of L octets)
406 * The output OKM is calculated as follows:
408 * N = ceil(L/HashLen)
409 * T = T(1) | T(2) | T(3) | ... | T(N)
410 * OKM = first L octets of T
413 * T(0) = empty string (zero length)
414 * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
415 * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02)
416 * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03)
419 * (where the constant concatenated to the end of each T(n) is a
422 static int HKDF_Expand(const EVP_MD *evp_md,
423 const unsigned char *prk, size_t prk_len,
424 const unsigned char *info, size_t info_len,
425 unsigned char *okm, size_t okm_len)
430 unsigned char prev[EVP_MAX_MD_SIZE];
431 size_t done_len = 0, dig_len, n;
433 sz = EVP_MD_size(evp_md);
436 dig_len = (size_t)sz;
438 /* calc: N = ceil(L/HashLen) */
439 n = okm_len / dig_len;
440 if (okm_len % dig_len)
443 if (n > 255 || okm == NULL)
446 if ((hmac = HMAC_CTX_new()) == NULL)
449 if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
452 for (i = 1; i <= n; i++) {
454 const unsigned char ctr = i;
456 /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */
458 if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
461 if (!HMAC_Update(hmac, prev, dig_len))
465 if (!HMAC_Update(hmac, info, info_len))
468 if (!HMAC_Update(hmac, &ctr, 1))
471 if (!HMAC_Final(hmac, prev, NULL))
474 copy_len = (done_len + dig_len > okm_len) ?
478 memcpy(okm + done_len, prev, copy_len);
480 done_len += copy_len;
485 OPENSSL_cleanse(prev, sizeof(prev));