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_FUNC_kdf_newctx_fn kdf_hkdf_new
;
35 static OSSL_FUNC_kdf_freectx_fn kdf_hkdf_free
;
36 static OSSL_FUNC_kdf_reset_fn kdf_hkdf_reset
;
37 static OSSL_FUNC_kdf_derive_fn kdf_hkdf_derive
;
38 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_hkdf_settable_ctx_params
;
39 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_hkdf_set_ctx_params
;
40 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_hkdf_gettable_ctx_params
;
41 static OSSL_FUNC_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
));