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
));