2 * Copyright 2016-2019 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
13 #include <openssl/hmac.h>
14 #include <openssl/evp.h>
15 #include <openssl/kdf.h>
16 #include <openssl/core_names.h>
17 #include "internal/cryptlib.h"
18 #include "internal/numbers.h"
19 #include "crypto/evp.h"
20 #include "internal/provider_ctx.h"
21 #include "internal/providercommonerr.h"
22 #include "internal/provider_algs.h"
23 #include "internal/provider_util.h"
26 #define HKDF_MAXBUF 1024
28 static OSSL_OP_kdf_newctx_fn kdf_hkdf_new;
29 static OSSL_OP_kdf_freectx_fn kdf_hkdf_free;
30 static OSSL_OP_kdf_reset_fn kdf_hkdf_reset;
31 static OSSL_OP_kdf_derive_fn kdf_hkdf_derive;
32 static OSSL_OP_kdf_settable_ctx_params_fn kdf_hkdf_settable_ctx_params;
33 static OSSL_OP_kdf_set_ctx_params_fn kdf_hkdf_set_ctx_params;
34 static OSSL_OP_kdf_gettable_ctx_params_fn kdf_hkdf_gettable_ctx_params;
35 static OSSL_OP_kdf_get_ctx_params_fn kdf_hkdf_get_ctx_params;
37 static int HKDF(const EVP_MD *evp_md,
38 const unsigned char *salt, size_t salt_len,
39 const unsigned char *key, size_t key_len,
40 const unsigned char *info, size_t info_len,
41 unsigned char *okm, size_t okm_len);
42 static int HKDF_Extract(const EVP_MD *evp_md,
43 const unsigned char *salt, size_t salt_len,
44 const unsigned char *ikm, size_t ikm_len,
45 unsigned char *prk, size_t prk_len);
46 static int HKDF_Expand(const EVP_MD *evp_md,
47 const unsigned char *prk, size_t prk_len,
48 const unsigned char *info, size_t info_len,
49 unsigned char *okm, size_t okm_len);
59 unsigned char info[HKDF_MAXBUF];
63 static void *kdf_hkdf_new(void *provctx)
67 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
68 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
70 ctx->provctx = provctx;
74 static void kdf_hkdf_free(void *vctx)
76 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
82 static void kdf_hkdf_reset(void *vctx)
84 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
86 ossl_prov_digest_reset(&ctx->digest);
87 OPENSSL_free(ctx->salt);
88 OPENSSL_clear_free(ctx->key, ctx->key_len);
89 OPENSSL_cleanse(ctx->info, ctx->info_len);
90 memset(ctx, 0, sizeof(*ctx));
93 static size_t kdf_hkdf_size(KDF_HKDF *ctx)
96 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
98 if (ctx->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY)
102 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
105 sz = EVP_MD_size(md);
112 static int kdf_hkdf_derive(void *vctx, unsigned char *key, size_t keylen)
114 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
115 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
118 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
121 if (ctx->key == NULL) {
122 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
127 case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
128 return HKDF(md, ctx->salt, ctx->salt_len, ctx->key,
129 ctx->key_len, ctx->info, ctx->info_len, key,
132 case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
133 return HKDF_Extract(md, ctx->salt, ctx->salt_len, ctx->key,
134 ctx->key_len, key, keylen);
136 case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
137 return HKDF_Expand(md, ctx->key, ctx->key_len, ctx->info,
138 ctx->info_len, key, keylen);
145 static int kdf_hkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
148 KDF_HKDF *ctx = vctx;
149 OPENSSL_CTX *provctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
152 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
155 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE)) != NULL) {
156 if (p->data_type == OSSL_PARAM_UTF8_STRING) {
157 if (strcasecmp(p->data, "EXTRACT_AND_EXPAND") == 0) {
158 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
159 } else if (strcasecmp(p->data, "EXTRACT_ONLY") == 0) {
160 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
161 } else if (strcasecmp(p->data, "EXPAND_ONLY") == 0) {
162 ctx->mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
164 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
167 } else if (OSSL_PARAM_get_int(p, &n)) {
168 if (n != EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND
169 && n != EVP_KDF_HKDF_MODE_EXTRACT_ONLY
170 && n != EVP_KDF_HKDF_MODE_EXPAND_ONLY) {
171 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
176 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
181 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) {
182 OPENSSL_clear_free(ctx->key, ctx->key_len);
184 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->key, 0,
189 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL) {
190 if (p->data_size != 0 && p->data != NULL) {
191 OPENSSL_free(ctx->salt);
193 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->salt, 0,
198 /* The info fields concatenate, so process them all */
199 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL) {
201 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
202 OSSL_KDF_PARAM_INFO)) {
203 const void *q = ctx->info + ctx->info_len;
206 if (p->data_size != 0
208 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
209 HKDF_MAXBUF - ctx->info_len,
218 static const OSSL_PARAM *kdf_hkdf_settable_ctx_params(void)
220 static const OSSL_PARAM known_settable_ctx_params[] = {
221 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
222 OSSL_PARAM_int(OSSL_KDF_PARAM_MODE, NULL),
223 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
224 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
225 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
226 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
227 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
230 return known_settable_ctx_params;
233 static int kdf_hkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
235 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
238 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
239 return OSSL_PARAM_set_size_t(p, kdf_hkdf_size(ctx));
243 static const OSSL_PARAM *kdf_hkdf_gettable_ctx_params(void)
245 static const OSSL_PARAM known_gettable_ctx_params[] = {
246 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
249 return known_gettable_ctx_params;
252 const OSSL_DISPATCH kdf_hkdf_functions[] = {
253 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_hkdf_new },
254 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_hkdf_free },
255 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_hkdf_reset },
256 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_hkdf_derive },
257 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
258 (void(*)(void))kdf_hkdf_settable_ctx_params },
259 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_hkdf_set_ctx_params },
260 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
261 (void(*)(void))kdf_hkdf_gettable_ctx_params },
262 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_hkdf_get_ctx_params },
267 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
268 * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and
269 * "Cryptographic Extraction and Key Derivation: The HKDF Scheme"
270 * Section 4.2 (https://eprint.iacr.org/2010/264.pdf).
273 * The scheme HKDF is specified as:
274 * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t)
277 * SKM is source key material
278 * XTS is extractor salt (which may be null or constant)
279 * CTXinfo is context information (may be null)
280 * L is the number of key bits to be produced by KDF
281 * k is the output length in bits of the hash function used with HMAC
283 * the value K(t) is truncated to its first d = L mod k bits.
286 * 2.2. Step 1: Extract
287 * HKDF-Extract(salt, IKM) -> PRK
288 * 2.3. Step 2: Expand
289 * HKDF-Expand(PRK, info, L) -> OKM
291 static int HKDF(const EVP_MD *evp_md,
292 const unsigned char *salt, size_t salt_len,
293 const unsigned char *ikm, size_t ikm_len,
294 const unsigned char *info, size_t info_len,
295 unsigned char *okm, size_t okm_len)
297 unsigned char prk[EVP_MAX_MD_SIZE];
301 sz = EVP_MD_size(evp_md);
304 prk_len = (size_t)sz;
306 /* Step 1: HKDF-Extract(salt, IKM) -> PRK */
307 if (!HKDF_Extract(evp_md, salt, salt_len, ikm, ikm_len, prk, prk_len))
310 /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */
311 ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
312 OPENSSL_cleanse(prk, sizeof(prk));
318 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
319 * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2).
321 * 2.2. Step 1: Extract
323 * HKDF-Extract(salt, IKM) -> PRK
326 * Hash a hash function; HashLen denotes the length of the
327 * hash function output in octets
330 * salt optional salt value (a non-secret random value);
331 * if not provided, it is set to a string of HashLen zeros.
332 * IKM input keying material
335 * PRK a pseudorandom key (of HashLen octets)
337 * The output PRK is calculated as follows:
339 * PRK = HMAC-Hash(salt, IKM)
341 static int HKDF_Extract(const EVP_MD *evp_md,
342 const unsigned char *salt, size_t salt_len,
343 const unsigned char *ikm, size_t ikm_len,
344 unsigned char *prk, size_t prk_len)
346 int sz = EVP_MD_size(evp_md);
350 if (prk_len != (size_t)sz) {
351 ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
354 /* calc: PRK = HMAC-Hash(salt, IKM) */
355 return HMAC(evp_md, salt, salt_len, ikm, ikm_len, prk, NULL) != NULL;
359 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
360 * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3).
362 * 2.3. Step 2: Expand
364 * HKDF-Expand(PRK, info, L) -> OKM
367 * Hash a hash function; HashLen denotes the length of the
368 * hash function output in octets
371 * PRK a pseudorandom key of at least HashLen octets
372 * (usually, the output from the extract step)
373 * info optional context and application specific information
374 * (can be a zero-length string)
375 * L length of output keying material in octets
379 * OKM output keying material (of L octets)
381 * The output OKM is calculated as follows:
383 * N = ceil(L/HashLen)
384 * T = T(1) | T(2) | T(3) | ... | T(N)
385 * OKM = first L octets of T
388 * T(0) = empty string (zero length)
389 * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
390 * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02)
391 * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03)
394 * (where the constant concatenated to the end of each T(n) is a
397 static int HKDF_Expand(const EVP_MD *evp_md,
398 const unsigned char *prk, size_t prk_len,
399 const unsigned char *info, size_t info_len,
400 unsigned char *okm, size_t okm_len)
405 unsigned char prev[EVP_MAX_MD_SIZE];
406 size_t done_len = 0, dig_len, n;
408 sz = EVP_MD_size(evp_md);
411 dig_len = (size_t)sz;
413 /* calc: N = ceil(L/HashLen) */
414 n = okm_len / dig_len;
415 if (okm_len % dig_len)
418 if (n > 255 || okm == NULL)
421 if ((hmac = HMAC_CTX_new()) == NULL)
424 if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
427 for (i = 1; i <= n; i++) {
429 const unsigned char ctr = i;
431 /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */
433 if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
436 if (!HMAC_Update(hmac, prev, dig_len))
440 if (!HMAC_Update(hmac, info, info_len))
443 if (!HMAC_Update(hmac, &ctr, 1))
446 if (!HMAC_Final(hmac, prev, NULL))
449 copy_len = (done_len + dig_len > okm_len) ?
453 memcpy(okm + done_len, prev, copy_len);
455 done_len += copy_len;
460 OPENSSL_cleanse(prev, sizeof(prev));