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 "prov/provider_ctx.h"
21 #include "prov/providercommonerr.h"
22 #include "prov/implementations.h"
23 #include "prov/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;
84 static void kdf_hkdf_reset(void *vctx)
86 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
88 ossl_prov_digest_reset(&ctx->digest);
89 OPENSSL_free(ctx->salt);
90 OPENSSL_clear_free(ctx->key, ctx->key_len);
91 OPENSSL_cleanse(ctx->info, ctx->info_len);
92 memset(ctx, 0, sizeof(*ctx));
95 static size_t kdf_hkdf_size(KDF_HKDF *ctx)
98 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
100 if (ctx->mode != EVP_KDF_HKDF_MODE_EXTRACT_ONLY)
104 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
107 sz = EVP_MD_size(md);
114 static int kdf_hkdf_derive(void *vctx, unsigned char *key, size_t keylen)
116 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
117 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
120 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
123 if (ctx->key == NULL) {
124 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_KEY);
129 case EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND:
130 return HKDF(md, ctx->salt, ctx->salt_len, ctx->key,
131 ctx->key_len, ctx->info, ctx->info_len, key,
134 case EVP_KDF_HKDF_MODE_EXTRACT_ONLY:
135 return HKDF_Extract(md, ctx->salt, ctx->salt_len, ctx->key,
136 ctx->key_len, key, keylen);
138 case EVP_KDF_HKDF_MODE_EXPAND_ONLY:
139 return HKDF_Expand(md, ctx->key, ctx->key_len, ctx->info,
140 ctx->info_len, key, keylen);
147 static int kdf_hkdf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
150 KDF_HKDF *ctx = vctx;
151 OPENSSL_CTX *provctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
154 if (!ossl_prov_digest_load_from_params(&ctx->digest, params, provctx))
157 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_MODE)) != NULL) {
158 if (p->data_type == OSSL_PARAM_UTF8_STRING) {
159 if (strcasecmp(p->data, "EXTRACT_AND_EXPAND") == 0) {
160 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND;
161 } else if (strcasecmp(p->data, "EXTRACT_ONLY") == 0) {
162 ctx->mode = EVP_KDF_HKDF_MODE_EXTRACT_ONLY;
163 } else if (strcasecmp(p->data, "EXPAND_ONLY") == 0) {
164 ctx->mode = EVP_KDF_HKDF_MODE_EXPAND_ONLY;
166 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
169 } else if (OSSL_PARAM_get_int(p, &n)) {
170 if (n != EVP_KDF_HKDF_MODE_EXTRACT_AND_EXPAND
171 && n != EVP_KDF_HKDF_MODE_EXTRACT_ONLY
172 && n != EVP_KDF_HKDF_MODE_EXPAND_ONLY) {
173 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
178 ERR_raise(ERR_LIB_PROV, PROV_R_INVALID_MODE);
183 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_KEY)) != NULL) {
184 OPENSSL_clear_free(ctx->key, ctx->key_len);
186 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->key, 0,
191 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SALT)) != NULL) {
192 if (p->data_size != 0 && p->data != NULL) {
193 OPENSSL_free(ctx->salt);
195 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->salt, 0,
200 /* The info fields concatenate, so process them all */
201 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_INFO)) != NULL) {
203 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
204 OSSL_KDF_PARAM_INFO)) {
205 const void *q = ctx->info + ctx->info_len;
208 if (p->data_size != 0
210 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
211 HKDF_MAXBUF - ctx->info_len,
220 static const OSSL_PARAM *kdf_hkdf_settable_ctx_params(void)
222 static const OSSL_PARAM known_settable_ctx_params[] = {
223 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_MODE, NULL, 0),
224 OSSL_PARAM_int(OSSL_KDF_PARAM_MODE, NULL),
225 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
226 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
227 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SALT, NULL, 0),
228 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_KEY, NULL, 0),
229 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_INFO, NULL, 0),
232 return known_settable_ctx_params;
235 static int kdf_hkdf_get_ctx_params(void *vctx, OSSL_PARAM params[])
237 KDF_HKDF *ctx = (KDF_HKDF *)vctx;
240 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
241 return OSSL_PARAM_set_size_t(p, kdf_hkdf_size(ctx));
245 static const OSSL_PARAM *kdf_hkdf_gettable_ctx_params(void)
247 static const OSSL_PARAM known_gettable_ctx_params[] = {
248 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
251 return known_gettable_ctx_params;
254 const OSSL_DISPATCH kdf_hkdf_functions[] = {
255 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_hkdf_new },
256 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_hkdf_free },
257 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_hkdf_reset },
258 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_hkdf_derive },
259 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
260 (void(*)(void))kdf_hkdf_settable_ctx_params },
261 { OSSL_FUNC_KDF_SET_CTX_PARAMS, (void(*)(void))kdf_hkdf_set_ctx_params },
262 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
263 (void(*)(void))kdf_hkdf_gettable_ctx_params },
264 { OSSL_FUNC_KDF_GET_CTX_PARAMS, (void(*)(void))kdf_hkdf_get_ctx_params },
269 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
270 * Section 2 (https://tools.ietf.org/html/rfc5869#section-2) and
271 * "Cryptographic Extraction and Key Derivation: The HKDF Scheme"
272 * Section 4.2 (https://eprint.iacr.org/2010/264.pdf).
275 * The scheme HKDF is specified as:
276 * HKDF(XTS, SKM, CTXinfo, L) = K(1) | K(2) | ... | K(t)
279 * SKM is source key material
280 * XTS is extractor salt (which may be null or constant)
281 * CTXinfo is context information (may be null)
282 * L is the number of key bits to be produced by KDF
283 * k is the output length in bits of the hash function used with HMAC
285 * the value K(t) is truncated to its first d = L mod k bits.
288 * 2.2. Step 1: Extract
289 * HKDF-Extract(salt, IKM) -> PRK
290 * 2.3. Step 2: Expand
291 * HKDF-Expand(PRK, info, L) -> OKM
293 static int HKDF(const EVP_MD *evp_md,
294 const unsigned char *salt, size_t salt_len,
295 const unsigned char *ikm, size_t ikm_len,
296 const unsigned char *info, size_t info_len,
297 unsigned char *okm, size_t okm_len)
299 unsigned char prk[EVP_MAX_MD_SIZE];
303 sz = EVP_MD_size(evp_md);
306 prk_len = (size_t)sz;
308 /* Step 1: HKDF-Extract(salt, IKM) -> PRK */
309 if (!HKDF_Extract(evp_md, salt, salt_len, ikm, ikm_len, prk, prk_len))
312 /* Step 2: HKDF-Expand(PRK, info, L) -> OKM */
313 ret = HKDF_Expand(evp_md, prk, prk_len, info, info_len, okm, okm_len);
314 OPENSSL_cleanse(prk, sizeof(prk));
320 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
321 * Section 2.2 (https://tools.ietf.org/html/rfc5869#section-2.2).
323 * 2.2. Step 1: Extract
325 * HKDF-Extract(salt, IKM) -> PRK
328 * Hash a hash function; HashLen denotes the length of the
329 * hash function output in octets
332 * salt optional salt value (a non-secret random value);
333 * if not provided, it is set to a string of HashLen zeros.
334 * IKM input keying material
337 * PRK a pseudorandom key (of HashLen octets)
339 * The output PRK is calculated as follows:
341 * PRK = HMAC-Hash(salt, IKM)
343 static int HKDF_Extract(const EVP_MD *evp_md,
344 const unsigned char *salt, size_t salt_len,
345 const unsigned char *ikm, size_t ikm_len,
346 unsigned char *prk, size_t prk_len)
348 int sz = EVP_MD_size(evp_md);
352 if (prk_len != (size_t)sz) {
353 ERR_raise(ERR_LIB_PROV, PROV_R_WRONG_OUTPUT_BUFFER_SIZE);
356 /* calc: PRK = HMAC-Hash(salt, IKM) */
357 return HMAC(evp_md, salt, salt_len, ikm, ikm_len, prk, NULL) != NULL;
361 * Refer to "HMAC-based Extract-and-Expand Key Derivation Function (HKDF)"
362 * Section 2.3 (https://tools.ietf.org/html/rfc5869#section-2.3).
364 * 2.3. Step 2: Expand
366 * HKDF-Expand(PRK, info, L) -> OKM
369 * Hash a hash function; HashLen denotes the length of the
370 * hash function output in octets
373 * PRK a pseudorandom key of at least HashLen octets
374 * (usually, the output from the extract step)
375 * info optional context and application specific information
376 * (can be a zero-length string)
377 * L length of output keying material in octets
381 * OKM output keying material (of L octets)
383 * The output OKM is calculated as follows:
385 * N = ceil(L/HashLen)
386 * T = T(1) | T(2) | T(3) | ... | T(N)
387 * OKM = first L octets of T
390 * T(0) = empty string (zero length)
391 * T(1) = HMAC-Hash(PRK, T(0) | info | 0x01)
392 * T(2) = HMAC-Hash(PRK, T(1) | info | 0x02)
393 * T(3) = HMAC-Hash(PRK, T(2) | info | 0x03)
396 * (where the constant concatenated to the end of each T(n) is a
399 static int HKDF_Expand(const EVP_MD *evp_md,
400 const unsigned char *prk, size_t prk_len,
401 const unsigned char *info, size_t info_len,
402 unsigned char *okm, size_t okm_len)
407 unsigned char prev[EVP_MAX_MD_SIZE];
408 size_t done_len = 0, dig_len, n;
410 sz = EVP_MD_size(evp_md);
413 dig_len = (size_t)sz;
415 /* calc: N = ceil(L/HashLen) */
416 n = okm_len / dig_len;
417 if (okm_len % dig_len)
420 if (n > 255 || okm == NULL)
423 if ((hmac = HMAC_CTX_new()) == NULL)
426 if (!HMAC_Init_ex(hmac, prk, prk_len, evp_md, NULL))
429 for (i = 1; i <= n; i++) {
431 const unsigned char ctr = i;
433 /* calc: T(i) = HMAC-Hash(PRK, T(i - 1) | info | i) */
435 if (!HMAC_Init_ex(hmac, NULL, 0, NULL, NULL))
438 if (!HMAC_Update(hmac, prev, dig_len))
442 if (!HMAC_Update(hmac, info, info_len))
445 if (!HMAC_Update(hmac, &ctr, 1))
448 if (!HMAC_Final(hmac, prev, NULL))
451 copy_len = (done_len + dig_len > okm_len) ?
455 memcpy(okm + done_len, prev, copy_len);
457 done_len += copy_len;
462 OPENSSL_cleanse(prev, sizeof(prev));