2 * Copyright 2016-2018 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 "internal/cryptlib.h"
52 #include <openssl/evp.h>
53 #include <openssl/kdf.h>
54 #include <openssl/core_names.h>
55 #include <openssl/params.h>
56 #include "internal/evp_int.h"
57 #include "kdf_local.h"
59 static void kdf_tls1_prf_reset(EVP_KDF_IMPL *impl);
60 static int tls1_prf_alg(const EVP_MD *md,
61 const unsigned char *sec, size_t slen,
62 const unsigned char *seed, size_t seed_len,
63 unsigned char *out, size_t olen);
65 #define TLS1_PRF_MAXBUF 1024
67 /* TLS KDF kdf context structure */
69 struct evp_kdf_impl_st {
70 /* Digest to use for PRF */
72 /* Secret value to use for PRF */
75 /* Buffer of concatenated seed data */
76 unsigned char seed[TLS1_PRF_MAXBUF];
80 static EVP_KDF_IMPL *kdf_tls1_prf_new(void)
84 if ((impl = OPENSSL_zalloc(sizeof(*impl))) == NULL)
85 KDFerr(KDF_F_KDF_TLS1_PRF_NEW, ERR_R_MALLOC_FAILURE);
89 static void kdf_tls1_prf_free(EVP_KDF_IMPL *impl)
91 kdf_tls1_prf_reset(impl);
95 static void kdf_tls1_prf_reset(EVP_KDF_IMPL *impl)
97 OPENSSL_clear_free(impl->sec, impl->seclen);
98 OPENSSL_cleanse(impl->seed, impl->seedlen);
99 memset(impl, 0, sizeof(*impl));
102 static int kdf_tls1_prf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
104 const unsigned char *p;
109 case EVP_KDF_CTRL_SET_MD:
110 md = va_arg(args, const EVP_MD *);
117 case EVP_KDF_CTRL_SET_TLS_SECRET:
118 p = va_arg(args, const unsigned char *);
119 len = va_arg(args, size_t);
120 OPENSSL_clear_free(impl->sec, impl->seclen);
121 impl->sec = OPENSSL_memdup(p, len);
122 if (impl->sec == NULL)
128 case EVP_KDF_CTRL_RESET_TLS_SEED:
129 OPENSSL_cleanse(impl->seed, impl->seedlen);
133 case EVP_KDF_CTRL_ADD_TLS_SEED:
134 p = va_arg(args, const unsigned char *);
135 len = va_arg(args, size_t);
136 if (len == 0 || p == NULL)
139 if (len > (TLS1_PRF_MAXBUF - impl->seedlen))
142 memcpy(impl->seed + impl->seedlen, p, len);
143 impl->seedlen += len;
151 static int kdf_tls1_prf_ctrl_str(EVP_KDF_IMPL *impl,
152 const char *type, const char *value)
155 KDFerr(KDF_F_KDF_TLS1_PRF_CTRL_STR, KDF_R_VALUE_MISSING);
158 if (strcmp(type, "digest") == 0)
159 return kdf_md2ctrl(impl, kdf_tls1_prf_ctrl, EVP_KDF_CTRL_SET_MD, value);
161 if (strcmp(type, "secret") == 0)
162 return kdf_str2ctrl(impl, kdf_tls1_prf_ctrl,
163 EVP_KDF_CTRL_SET_TLS_SECRET, value);
165 if (strcmp(type, "hexsecret") == 0)
166 return kdf_hex2ctrl(impl, kdf_tls1_prf_ctrl,
167 EVP_KDF_CTRL_SET_TLS_SECRET, value);
169 if (strcmp(type, "seed") == 0)
170 return kdf_str2ctrl(impl, kdf_tls1_prf_ctrl, EVP_KDF_CTRL_ADD_TLS_SEED,
173 if (strcmp(type, "hexseed") == 0)
174 return kdf_hex2ctrl(impl, kdf_tls1_prf_ctrl, EVP_KDF_CTRL_ADD_TLS_SEED,
180 static int kdf_tls1_prf_derive(EVP_KDF_IMPL *impl, unsigned char *key,
183 if (impl->md == NULL) {
184 KDFerr(KDF_F_KDF_TLS1_PRF_DERIVE, KDF_R_MISSING_MESSAGE_DIGEST);
187 if (impl->sec == NULL) {
188 KDFerr(KDF_F_KDF_TLS1_PRF_DERIVE, KDF_R_MISSING_SECRET);
191 if (impl->seedlen == 0) {
192 KDFerr(KDF_F_KDF_TLS1_PRF_DERIVE, KDF_R_MISSING_SEED);
195 return tls1_prf_alg(impl->md, impl->sec, impl->seclen,
196 impl->seed, impl->seedlen,
200 const EVP_KDF tls1_prf_kdf_meth = {
206 kdf_tls1_prf_ctrl_str,
212 * Refer to "The TLS Protocol Version 1.0" Section 5
213 * (https://tools.ietf.org/html/rfc2246#section-5) and
214 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
215 * (https://tools.ietf.org/html/rfc5246#section-5).
217 * P_<hash> is an expansion function that uses a single hash function to expand
218 * a secret and seed into an arbitrary quantity of output:
220 * P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
221 * HMAC_<hash>(secret, A(2) + seed) +
222 * HMAC_<hash>(secret, A(3) + seed) + ...
224 * where + indicates concatenation. P_<hash> can be iterated as many times as
225 * is necessary to produce the required quantity of data.
227 * A(i) is defined as:
229 * A(i) = HMAC_<hash>(secret, A(i-1))
231 static int tls1_prf_P_hash(const EVP_MD *md,
232 const unsigned char *sec, size_t sec_len,
233 const unsigned char *seed, size_t seed_len,
234 unsigned char *out, size_t olen)
238 EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL, *ctx_init = NULL;
239 unsigned char Ai[EVP_MAX_MD_SIZE];
242 OSSL_PARAM params[4];
244 const char *mdname = EVP_MD_name(md);
246 mac = EVP_MAC_fetch(NULL, OSSL_MAC_NAME_HMAC, NULL); /* Implicit fetch */
247 ctx_init = EVP_MAC_CTX_new(mac);
248 if (ctx_init == NULL)
251 /* TODO(3.0) rethink "flags", also see hmac.c in providers */
252 mac_flags = EVP_MD_CTX_FLAG_NON_FIPS_ALLOW;
253 params[0] = OSSL_PARAM_construct_int(OSSL_MAC_PARAM_FLAGS, &mac_flags);
254 params[1] = OSSL_PARAM_construct_utf8_string(OSSL_MAC_PARAM_DIGEST,
257 params[2] = OSSL_PARAM_construct_octet_string(OSSL_MAC_PARAM_KEY,
258 (void *)sec, sec_len);
259 params[3] = OSSL_PARAM_construct_end();
260 if (!EVP_MAC_CTX_set_params(ctx_init, params))
262 if (!EVP_MAC_init(ctx_init))
264 chunk = EVP_MAC_size(ctx_init);
268 ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
271 if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
275 /* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
276 if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len, sizeof(Ai)))
278 EVP_MAC_CTX_free(ctx_Ai);
281 /* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
282 ctx = EVP_MAC_CTX_dup(ctx_init);
285 if (!EVP_MAC_update(ctx, Ai, Ai_len))
287 /* save state for calculating next A(i) value */
289 ctx_Ai = EVP_MAC_CTX_dup(ctx);
293 if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
296 /* last chunk - use Ai as temp bounce buffer */
297 if (!EVP_MAC_final(ctx, Ai, &Ai_len, sizeof(Ai)))
299 memcpy(out, Ai, olen);
302 if (!EVP_MAC_final(ctx, out, NULL, olen))
304 EVP_MAC_CTX_free(ctx);
311 EVP_MAC_CTX_free(ctx);
312 EVP_MAC_CTX_free(ctx_Ai);
313 EVP_MAC_CTX_free(ctx_init);
315 OPENSSL_cleanse(Ai, sizeof(Ai));
320 * Refer to "The TLS Protocol Version 1.0" Section 5
321 * (https://tools.ietf.org/html/rfc2246#section-5) and
322 * "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
323 * (https://tools.ietf.org/html/rfc5246#section-5).
325 * For TLS v1.0 and TLS v1.1:
327 * PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
328 * P_SHA-1(S2, label + seed)
330 * S1 is taken from the first half of the secret, S2 from the second half.
332 * L_S = length in bytes of secret;
333 * L_S1 = L_S2 = ceil(L_S / 2);
337 * PRF(secret, label, seed) = P_<hash>(secret, label + seed)
339 static int tls1_prf_alg(const EVP_MD *md,
340 const unsigned char *sec, size_t slen,
341 const unsigned char *seed, size_t seed_len,
342 unsigned char *out, size_t olen)
344 if (EVP_MD_type(md) == NID_md5_sha1) {
345 /* TLS v1.0 and TLS v1.1 */
348 /* calc: L_S1 = L_S2 = ceil(L_S / 2) */
349 size_t L_S1 = (slen + 1) / 2;
352 if (!tls1_prf_P_hash(EVP_md5(), sec, L_S1,
353 seed, seed_len, out, olen))
356 if ((tmp = OPENSSL_malloc(olen)) == NULL) {
357 KDFerr(KDF_F_TLS1_PRF_ALG, ERR_R_MALLOC_FAILURE);
360 if (!tls1_prf_P_hash(EVP_sha1(), sec + slen - L_S2, L_S2,
361 seed, seed_len, tmp, olen)) {
362 OPENSSL_clear_free(tmp, olen);
365 for (i = 0; i < olen; i++)
367 OPENSSL_clear_free(tmp, olen);
372 if (!tls1_prf_P_hash(md, sec, slen, seed, seed_len, out, olen))