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 * Refer to "The TLS Protocol Version 1.0" Section 5
12 * (https://tools.ietf.org/html/rfc2246#section-5) and
13 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
14 * (https://tools.ietf.org/html/rfc5246#section-5).
16 * For TLS v1.0 and TLS v1.1 the TLS PRF algorithm is given by:
18 * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
19 * P_SHA-1(S2, label + seed)
21 * where P_MD5 and P_SHA-1 are defined by P_<hash>, below, and S1 and S2 are
22 * two halves of the secret (with the possibility of one shared byte, in the
23 * case where the length of the original secret is odd). S1 is taken from the
24 * first half of the secret, S2 from the second half.
26 * For TLS v1.2 the TLS PRF algorithm is given by:
28 * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
30 * where hash is SHA-256 for all cipher suites defined in RFC 5246 as well as
31 * those published prior to TLS v1.2 while the TLS v1.2 protocol is in effect,
32 * unless defined otherwise by the cipher suite.
34 * P_<hash> is an expansion function that uses a single hash function to expand
35 * a secret and seed into an arbitrary quantity of output:
37 * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
38 * HMAC_<hash>(secret, A(2) + seed) +
39 * HMAC_<hash>(secret, A(3) + seed) + ...
41 * where + indicates concatenation. P_<hash> can be iterated as many times as
42 * is necessary to produce the required quantity of data.
46 * A(i) = HMAC_<hash>(secret, A(i-1))
51 #include <openssl/evp.h>
52 #include <openssl/kdf.h>
53 #include <openssl/core_names.h>
54 #include <openssl/params.h>
55 #include "internal/cryptlib.h"
56 #include "internal/numbers.h"
57 #include "crypto/evp.h"
58 #include "prov/provider_ctx.h"
59 #include "prov/providercommon.h"
60 #include "prov/providercommonerr.h"
61 #include "prov/implementations.h"
62 #include "prov/provider_util.h"
65 static OSSL_FUNC_kdf_newctx_fn kdf_tls1_prf_new
;
66 static OSSL_FUNC_kdf_freectx_fn kdf_tls1_prf_free
;
67 static OSSL_FUNC_kdf_reset_fn kdf_tls1_prf_reset
;
68 static OSSL_FUNC_kdf_derive_fn kdf_tls1_prf_derive
;
69 static OSSL_FUNC_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params
;
70 static OSSL_FUNC_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params
;
71 static OSSL_FUNC_kdf_gettable_ctx_params_fn kdf_tls1_prf_gettable_ctx_params
;
72 static OSSL_FUNC_kdf_get_ctx_params_fn kdf_tls1_prf_get_ctx_params
;
74 static int tls1_prf_alg(EVP_MAC_CTX
*mdctx
, EVP_MAC_CTX
*sha1ctx
,
75 const unsigned char *sec
, size_t slen
,
76 const unsigned char *seed
, size_t seed_len
,
77 unsigned char *out
, size_t olen
);
79 #define TLS1_PRF_MAXBUF 1024
81 /* TLS KDF kdf context structure */
85 /* MAC context for the main digest */
87 /* MAC context for SHA1 for the MD5/SHA-1 combined PRF */
90 /* Secret value to use for PRF */
93 /* Buffer of concatenated seed data */
94 unsigned char seed
[TLS1_PRF_MAXBUF
];
98 static void *kdf_tls1_prf_new(void *provctx
)
102 if (!ossl_prov_is_running())
105 if ((ctx
= OPENSSL_zalloc(sizeof(*ctx
))) == NULL
)
106 ERR_raise(ERR_LIB_PROV
, ERR_R_MALLOC_FAILURE
);
107 ctx
->provctx
= provctx
;
111 static void kdf_tls1_prf_free(void *vctx
)
113 TLS1_PRF
*ctx
= (TLS1_PRF
*)vctx
;
116 kdf_tls1_prf_reset(ctx
);
121 static void kdf_tls1_prf_reset(void *vctx
)
123 TLS1_PRF
*ctx
= (TLS1_PRF
*)vctx
;
124 void *provctx
= ctx
->provctx
;
126 EVP_MAC_CTX_free(ctx
->P_hash
);
127 EVP_MAC_CTX_free(ctx
->P_sha1
);
128 OPENSSL_clear_free(ctx
->sec
, ctx
->seclen
);
129 OPENSSL_cleanse(ctx
->seed
, ctx
->seedlen
);
130 memset(ctx
, 0, sizeof(*ctx
));
131 ctx
->provctx
= provctx
;
134 static int kdf_tls1_prf_derive(void *vctx
, unsigned char *key
,
137 TLS1_PRF
*ctx
= (TLS1_PRF
*)vctx
;
139 if (!ossl_prov_is_running())
142 if (ctx
->P_hash
== NULL
) {
143 ERR_raise(ERR_LIB_PROV
, PROV_R_MISSING_MESSAGE_DIGEST
);
146 if (ctx
->sec
== NULL
) {
147 ERR_raise(ERR_LIB_PROV
, PROV_R_MISSING_SECRET
);
150 if (ctx
->seedlen
== 0) {
151 ERR_raise(ERR_LIB_PROV
, PROV_R_MISSING_SEED
);
155 ERR_raise(ERR_LIB_PROV
, PROV_R_INVALID_KEY_LENGTH
);
159 return tls1_prf_alg(ctx
->P_hash
, ctx
->P_sha1
,
160 ctx
->sec
, ctx
->seclen
,
161 ctx
->seed
, ctx
->seedlen
,
165 static int kdf_tls1_prf_set_ctx_params(void *vctx
, const OSSL_PARAM params
[])
168 TLS1_PRF
*ctx
= vctx
;
169 OSSL_LIB_CTX
*libctx
= PROV_LIBRARY_CONTEXT_OF(ctx
->provctx
);
171 if ((p
= OSSL_PARAM_locate_const(params
, OSSL_KDF_PARAM_DIGEST
)) != NULL
) {
172 if (strcasecmp(p
->data
, SN_md5_sha1
) == 0) {
173 if (!ossl_prov_macctx_load_from_params(&ctx
->P_hash
, params
,
175 NULL
, SN_md5
, libctx
)
176 || !ossl_prov_macctx_load_from_params(&ctx
->P_sha1
, params
,
178 NULL
, SN_sha1
, libctx
))
181 EVP_MAC_CTX_free(ctx
->P_sha1
);
182 if (!ossl_prov_macctx_load_from_params(&ctx
->P_hash
, params
,
189 if ((p
= OSSL_PARAM_locate_const(params
, OSSL_KDF_PARAM_SECRET
)) != NULL
) {
190 OPENSSL_clear_free(ctx
->sec
, ctx
->seclen
);
192 if (!OSSL_PARAM_get_octet_string(p
, (void **)&ctx
->sec
, 0, &ctx
->seclen
))
195 /* The seed fields concatenate, so process them all */
196 if ((p
= OSSL_PARAM_locate_const(params
, OSSL_KDF_PARAM_SEED
)) != NULL
) {
197 for (; p
!= NULL
; p
= OSSL_PARAM_locate_const(p
+ 1,
198 OSSL_KDF_PARAM_SEED
)) {
199 const void *q
= ctx
->seed
+ ctx
->seedlen
;
202 if (p
->data_size
!= 0
204 && !OSSL_PARAM_get_octet_string(p
, (void **)&q
,
205 TLS1_PRF_MAXBUF
- ctx
->seedlen
,
214 static const OSSL_PARAM
*kdf_tls1_prf_settable_ctx_params(ossl_unused
void *ctx
)
216 static const OSSL_PARAM known_settable_ctx_params
[] = {
217 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES
, NULL
, 0),
218 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST
, NULL
, 0),
219 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET
, NULL
, 0),
220 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED
, NULL
, 0),
223 return known_settable_ctx_params
;
226 static int kdf_tls1_prf_get_ctx_params(void *vctx
, OSSL_PARAM params
[])
230 if ((p
= OSSL_PARAM_locate(params
, OSSL_KDF_PARAM_SIZE
)) != NULL
)
231 return OSSL_PARAM_set_size_t(p
, SIZE_MAX
);
235 static const OSSL_PARAM
*kdf_tls1_prf_gettable_ctx_params(ossl_unused
void *ctx
)
237 static const OSSL_PARAM known_gettable_ctx_params
[] = {
238 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE
, NULL
),
241 return known_gettable_ctx_params
;
244 const OSSL_DISPATCH ossl_kdf_tls1_prf_functions
[] = {
245 { OSSL_FUNC_KDF_NEWCTX
, (void(*)(void))kdf_tls1_prf_new
},
246 { OSSL_FUNC_KDF_FREECTX
, (void(*)(void))kdf_tls1_prf_free
},
247 { OSSL_FUNC_KDF_RESET
, (void(*)(void))kdf_tls1_prf_reset
},
248 { OSSL_FUNC_KDF_DERIVE
, (void(*)(void))kdf_tls1_prf_derive
},
249 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS
,
250 (void(*)(void))kdf_tls1_prf_settable_ctx_params
},
251 { OSSL_FUNC_KDF_SET_CTX_PARAMS
,
252 (void(*)(void))kdf_tls1_prf_set_ctx_params
},
253 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS
,
254 (void(*)(void))kdf_tls1_prf_gettable_ctx_params
},
255 { OSSL_FUNC_KDF_GET_CTX_PARAMS
,
256 (void(*)(void))kdf_tls1_prf_get_ctx_params
},
261 * Refer to "The TLS Protocol Version 1.0" Section 5
262 * (https://tools.ietf.org/html/rfc2246#section-5) and
263 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
264 * (https://tools.ietf.org/html/rfc5246#section-5).
266 * P_<hash> is an expansion function that uses a single hash function to expand
267 * a secret and seed into an arbitrary quantity of output:
269 * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
270 * HMAC_<hash>(secret, A(2) + seed) +
271 * HMAC_<hash>(secret, A(3) + seed) + ...
273 * where + indicates concatenation. P_<hash> can be iterated as many times as
274 * is necessary to produce the required quantity of data.
276 * A(i) is defined as:
278 * A(i) = HMAC_<hash>(secret, A(i-1))
280 static int tls1_prf_P_hash(EVP_MAC_CTX
*ctx_init
,
281 const unsigned char *sec
, size_t sec_len
,
282 const unsigned char *seed
, size_t seed_len
,
283 unsigned char *out
, size_t olen
)
286 EVP_MAC_CTX
*ctx
= NULL
, *ctx_Ai
= NULL
;
287 unsigned char Ai
[EVP_MAX_MD_SIZE
];
290 OSSL_PARAM params
[2], *p
= params
;
292 *p
++ = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY
,
293 (void *)sec
, sec_len
);
294 *p
= OSSL_PARAM_construct_end();
295 if (!EVP_MAC_CTX_set_params(ctx_init
, params
))
297 if (!EVP_MAC_init(ctx_init
))
299 chunk
= EVP_MAC_size(ctx_init
);
303 ctx_Ai
= EVP_MAC_CTX_dup(ctx_init
);
306 if (seed
!= NULL
&& !EVP_MAC_update(ctx_Ai
, seed
, seed_len
))
310 /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
311 if (!EVP_MAC_final(ctx_Ai
, Ai
, &Ai_len
, sizeof(Ai
)))
313 EVP_MAC_CTX_free(ctx_Ai
);
316 /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
317 ctx
= EVP_MAC_CTX_dup(ctx_init
);
320 if (!EVP_MAC_update(ctx
, Ai
, Ai_len
))
322 /* save state for calculating next A(i) value */
324 ctx_Ai
= EVP_MAC_CTX_dup(ctx
);
328 if (seed
!= NULL
&& !EVP_MAC_update(ctx
, seed
, seed_len
))
331 /* last chunk - use Ai as temp bounce buffer */
332 if (!EVP_MAC_final(ctx
, Ai
, &Ai_len
, sizeof(Ai
)))
334 memcpy(out
, Ai
, olen
);
337 if (!EVP_MAC_final(ctx
, out
, NULL
, olen
))
339 EVP_MAC_CTX_free(ctx
);
346 EVP_MAC_CTX_free(ctx
);
347 EVP_MAC_CTX_free(ctx_Ai
);
348 OPENSSL_cleanse(Ai
, sizeof(Ai
));
353 * Refer to "The TLS Protocol Version 1.0" Section 5
354 * (https://tools.ietf.org/html/rfc2246#section-5) and
355 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
356 * (https://tools.ietf.org/html/rfc5246#section-5).
358 * For TLS v1.0 and TLS v1.1:
360 * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
361 * P_SHA-1(S2, label + seed)
363 * S1 is taken from the first half of the secret, S2 from the second half.
365 * L_S = length in bytes of secret;
366 * L_S1 = L_S2 = ceil(L_S / 2);
370 * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
372 static int tls1_prf_alg(EVP_MAC_CTX
*mdctx
, EVP_MAC_CTX
*sha1ctx
,
373 const unsigned char *sec
, size_t slen
,
374 const unsigned char *seed
, size_t seed_len
,
375 unsigned char *out
, size_t olen
)
377 if (sha1ctx
!= NULL
) {
378 /* TLS v1.0 and TLS v1.1 */
381 /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
382 size_t L_S1
= (slen
+ 1) / 2;
385 if (!tls1_prf_P_hash(mdctx
, sec
, L_S1
,
386 seed
, seed_len
, out
, olen
))
389 if ((tmp
= OPENSSL_malloc(olen
)) == NULL
) {
390 ERR_raise(ERR_LIB_PROV
, ERR_R_MALLOC_FAILURE
);
394 if (!tls1_prf_P_hash(sha1ctx
, sec
+ slen
- L_S2
, L_S2
,
395 seed
, seed_len
, tmp
, olen
)) {
396 OPENSSL_clear_free(tmp
, olen
);
399 for (i
= 0; i
< olen
; i
++)
401 OPENSSL_clear_free(tmp
, olen
);
406 if (!tls1_prf_P_hash(mdctx
, sec
, slen
, seed
, seed_len
, out
, olen
))