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
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 "internal/evp_int.h"
58 #include "internal/provider_ctx.h"
59 #include "internal/providercommonerr.h"
60 #include "internal/provider_algs.h"
61 #include "internal/provider_util.h"
64 static OSSL_OP_kdf_newctx_fn kdf_tls1_prf_new;
65 static OSSL_OP_kdf_freectx_fn kdf_tls1_prf_free;
66 static OSSL_OP_kdf_reset_fn kdf_tls1_prf_reset;
67 static OSSL_OP_kdf_derive_fn kdf_tls1_prf_derive;
68 static OSSL_OP_kdf_settable_ctx_params_fn kdf_tls1_prf_settable_ctx_params;
69 static OSSL_OP_kdf_set_ctx_params_fn kdf_tls1_prf_set_ctx_params;
71 static int tls1_prf_alg(const EVP_MD *md, const EVP_MD *sha1,
72 const unsigned char *sec, size_t slen,
73 const unsigned char *seed, size_t seed_len,
74 unsigned char *out, size_t olen);
76 #define TLS1_PRF_MAXBUF 1024
78 /* TLS KDF kdf context structure */
81 /* Digest to use for PRF */
83 /* Second digest for the MD5/SHA-1 combined PRF */
85 /* Secret value to use for PRF */
88 /* Buffer of concatenated seed data */
89 unsigned char seed[TLS1_PRF_MAXBUF];
93 static void *kdf_tls1_prf_new(void *provctx)
97 if ((ctx = OPENSSL_zalloc(sizeof(*ctx))) == NULL)
98 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
99 ctx->provctx = provctx;
103 static void kdf_tls1_prf_free(void *vctx)
105 TLS1_PRF *ctx = (TLS1_PRF *)vctx;
107 kdf_tls1_prf_reset(ctx);
111 static void kdf_tls1_prf_reset(void *vctx)
113 TLS1_PRF *ctx = (TLS1_PRF *)vctx;
115 ossl_prov_digest_reset(&ctx->sha1);
116 ossl_prov_digest_reset(&ctx->digest);
117 OPENSSL_clear_free(ctx->sec, ctx->seclen);
118 OPENSSL_cleanse(ctx->seed, ctx->seedlen);
119 memset(ctx, 0, sizeof(*ctx));
122 static int kdf_tls1_prf_derive(void *vctx, unsigned char *key,
125 TLS1_PRF *ctx = (TLS1_PRF *)vctx;
126 const EVP_MD *md = ossl_prov_digest_md(&ctx->digest);
129 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_MESSAGE_DIGEST);
132 if (ctx->sec == NULL) {
133 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SECRET);
136 if (ctx->seedlen == 0) {
137 ERR_raise(ERR_LIB_PROV, PROV_R_MISSING_SEED);
140 return tls1_prf_alg(md, ossl_prov_digest_md(&ctx->sha1),
141 ctx->sec, ctx->seclen,
142 ctx->seed, ctx->seedlen,
146 static int kdf_tls1_prf_set_ctx_params(void *vctx, const OSSL_PARAM params[])
149 TLS1_PRF *ctx = vctx;
150 OPENSSL_CTX *provctx = PROV_LIBRARY_CONTEXT_OF(ctx->provctx);
152 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_DIGEST)) != NULL
153 && p->data_type == OSSL_PARAM_UTF8_STRING
154 && strcasecmp(p->data, SN_md5_sha1) == 0) {
155 OSSL_PARAM qaram[4], *q = qaram;
157 /* Handle combined MD5 / SHA1 digest specially */
158 *q++ = OSSL_PARAM_construct_utf8_string("digest", SN_md5, 0);
159 if ((p = OSSL_PARAM_locate_const(params, "engine")) != NULL)
161 if ((p = OSSL_PARAM_locate_const(params, "properties")) != NULL)
163 *q = OSSL_PARAM_construct_end();
164 if (!ossl_prov_digest_load_from_params(&ctx->digest, qaram, provctx))
166 qaram[0] = OSSL_PARAM_construct_utf8_string("digest", SN_sha1, 0);
167 if (!ossl_prov_digest_load_from_params(&ctx->sha1, qaram, provctx))
169 } else if (!ossl_prov_digest_load_from_params(&ctx->digest, params,
174 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SECRET)) != NULL) {
175 OPENSSL_clear_free(ctx->sec, ctx->seclen);
177 if (!OSSL_PARAM_get_octet_string(p, (void **)&ctx->sec, 0, &ctx->seclen))
180 /* The seed fields concatenate, so process them all */
181 if ((p = OSSL_PARAM_locate_const(params, OSSL_KDF_PARAM_SEED)) != NULL) {
182 OPENSSL_cleanse(ctx->seed, ctx->seedlen);
185 for (; p != NULL; p = OSSL_PARAM_locate_const(p + 1,
186 OSSL_KDF_PARAM_SEED)) {
187 const void *q = ctx->seed + ctx->seedlen;
190 if (p->data_size != 0
192 && !OSSL_PARAM_get_octet_string(p, (void **)&q,
193 TLS1_PRF_MAXBUF - ctx->seedlen,
202 static const OSSL_PARAM *kdf_tls1_prf_settable_ctx_params(void)
204 static const OSSL_PARAM known_settable_ctx_params[] = {
205 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_PROPERTIES, NULL, 0),
206 OSSL_PARAM_utf8_string(OSSL_KDF_PARAM_DIGEST, NULL, 0),
207 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SECRET, NULL, 0),
208 OSSL_PARAM_octet_string(OSSL_KDF_PARAM_SEED, NULL, 0),
211 return known_settable_ctx_params;
214 static int kdf_tls1_prf_get_ctx_params(void *vctx, OSSL_PARAM params[])
218 if ((p = OSSL_PARAM_locate(params, OSSL_KDF_PARAM_SIZE)) != NULL)
219 return OSSL_PARAM_set_size_t(p, SIZE_MAX);
223 static const OSSL_PARAM *kdf_tls1_prf_gettable_ctx_params(void)
225 static const OSSL_PARAM known_gettable_ctx_params[] = {
226 OSSL_PARAM_size_t(OSSL_KDF_PARAM_SIZE, NULL),
229 return known_gettable_ctx_params;
232 const OSSL_DISPATCH kdf_tls1_prf_functions[] = {
233 { OSSL_FUNC_KDF_NEWCTX, (void(*)(void))kdf_tls1_prf_new },
234 { OSSL_FUNC_KDF_FREECTX, (void(*)(void))kdf_tls1_prf_free },
235 { OSSL_FUNC_KDF_RESET, (void(*)(void))kdf_tls1_prf_reset },
236 { OSSL_FUNC_KDF_DERIVE, (void(*)(void))kdf_tls1_prf_derive },
237 { OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS,
238 (void(*)(void))kdf_tls1_prf_settable_ctx_params },
239 { OSSL_FUNC_KDF_SET_CTX_PARAMS,
240 (void(*)(void))kdf_tls1_prf_set_ctx_params },
241 { OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS,
242 (void(*)(void))kdf_tls1_prf_gettable_ctx_params },
243 { OSSL_FUNC_KDF_GET_CTX_PARAMS,
244 (void(*)(void))kdf_tls1_prf_get_ctx_params },
249 * Refer to "The TLS Protocol Version 1.0" Section 5
250 * (https://tools.ietf.org/html/rfc2246#section-5) and
251 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
252 * (https://tools.ietf.org/html/rfc5246#section-5).
254 * P_<hash> is an expansion function that uses a single hash function to expand
255 * a secret and seed into an arbitrary quantity of output:
257 * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
258 * HMAC_<hash>(secret, A(2) + seed) +
259 * HMAC_<hash>(secret, A(3) + seed) + ...
261 * where + indicates concatenation. P_<hash> can be iterated as many times as
262 * is necessary to produce the required quantity of data.
264 * A(i) is defined as:
266 * A(i) = HMAC_<hash>(secret, A(i-1))
268 static int tls1_prf_P_hash(const EVP_MD *md,
269 const unsigned char *sec, size_t sec_len,
270 const unsigned char *seed, size_t seed_len,
271 unsigned char *out, size_t olen)
275 EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL, *ctx_init = NULL;
276 unsigned char Ai[EVP_MAX_MD_SIZE];
279 OSSL_PARAM params[4];
281 const char *mdname = EVP_MD_name(md);
283 mac = EVP_MAC_fetch(NULL, OSSL_MAC_NAME_HMAC, NULL); /* Implicit fetch */
284 ctx_init = EVP_MAC_CTX_new(mac);
285 if (ctx_init == NULL)
288 /* TODO(3.0) rethink "flags", also see hmac.c in providers */
289 mac_flags = EVP_MD_CTX_FLAG_NON_FIPS_ALLOW;
290 params[0] = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_FLAGS, &mac_flags);
291 params[1] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST,
293 params[2] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
294 (void *)sec, sec_len);
295 params[3] = OSSL_PARAM_construct_end();
296 if (!EVP_MAC_CTX_set_params(ctx_init, params))
298 if (!EVP_MAC_init(ctx_init))
300 chunk = EVP_MAC_size(ctx_init);
304 ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
307 if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
311 /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
312 if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
314 EVP_MAC_CTX_free(ctx_Ai);
317 /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
318 ctx = EVP_MAC_CTX_dup(ctx_init);
321 if (!EVP_MAC_update(ctx, Ai, Ai_len))
323 /* save state for calculating next A(i) value */
325 ctx_Ai = EVP_MAC_CTX_dup(ctx);
329 if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
332 /* last chunk - use Ai as temp bounce buffer */
333 if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
335 memcpy(out, Ai, olen);
338 if (!EVP_MAC_final(ctx, out, NULL, olen))
340 EVP_MAC_CTX_free(ctx);
347 EVP_MAC_CTX_free(ctx);
348 EVP_MAC_CTX_free(ctx_Ai);
349 EVP_MAC_CTX_free(ctx_init);
351 OPENSSL_cleanse(Ai, sizeof(Ai));
356 * Refer to "The TLS Protocol Version 1.0" Section 5
357 * (https://tools.ietf.org/html/rfc2246#section-5) and
358 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
359 * (https://tools.ietf.org/html/rfc5246#section-5).
361 * For TLS v1.0 and TLS v1.1:
363 * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
364 * P_SHA-1(S2, label + seed)
366 * S1 is taken from the first half of the secret, S2 from the second half.
368 * L_S = length in bytes of secret;
369 * L_S1 = L_S2 = ceil(L_S / 2);
373 * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
375 static int tls1_prf_alg(const EVP_MD *md, const EVP_MD *sha1,
376 const unsigned char *sec, size_t slen,
377 const unsigned char *seed, size_t seed_len,
378 unsigned char *out, size_t olen)
381 /* TLS v1.0 and TLS v1.1 */
384 /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
385 size_t L_S1 = (slen + 1) / 2;
388 if (!tls1_prf_P_hash(md, sec, L_S1,
389 seed, seed_len, out, olen))
392 if ((tmp = OPENSSL_malloc(olen)) == NULL) {
393 ERR_raise(ERR_LIB_PROV, ERR_R_MALLOC_FAILURE);
396 if (!tls1_prf_P_hash(sha1, sec + slen - L_S2, L_S2,
397 seed, seed_len, tmp, olen)) {
398 OPENSSL_clear_free(tmp, olen);
401 for (i = 0; i < olen; i++)
403 OPENSSL_clear_free(tmp, olen);
408 if (!tls1_prf_P_hash(md, sec, slen, seed, seed_len, out, olen))