362 lines
11 KiB
C
362 lines
11 KiB
C
/*
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* Copyright 2016-2018 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the Apache License 2.0 (the "License"). You may not use
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* this file except in compliance with the License. You can obtain a copy
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* in the file LICENSE in the source distribution or at
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* https://www.openssl.org/source/license.html
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*/
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/*
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* Refer to "The TLS Protocol Version 1.0" Section 5
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* (https://tools.ietf.org/html/rfc2246#section-5) and
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* "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
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* (https://tools.ietf.org/html/rfc5246#section-5).
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*
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* For TLS v1.0 and TLS v1.1 the TLS PRF algorithm is given by:
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*
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* PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
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* P_SHA-1(S2, label + seed)
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*
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* where P_MD5 and P_SHA-1 are defined by P_<hash>, below, and S1 and S2 are
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* two halves of the secret (with the possibility of one shared byte, in the
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* case where the length of the original secret is odd). S1 is taken from the
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* first half of the secret, S2 from the second half.
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*
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* For TLS v1.2 the TLS PRF algorithm is given by:
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*
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* PRF(secret, label, seed) = P_<hash>(secret, label + seed)
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*
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* where hash is SHA-256 for all cipher suites defined in RFC 5246 as well as
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* those published prior to TLS v1.2 while the TLS v1.2 protocol is in effect,
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* unless defined otherwise by the cipher suite.
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*
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* P_<hash> is an expansion function that uses a single hash function to expand
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* a secret and seed into an arbitrary quantity of output:
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*
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* P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
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* HMAC_<hash>(secret, A(2) + seed) +
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* HMAC_<hash>(secret, A(3) + seed) + ...
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*
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* where + indicates concatenation. P_<hash> can be iterated as many times as
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* is necessary to produce the required quantity of data.
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*
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* A(i) is defined as:
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* A(0) = seed
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* A(i) = HMAC_<hash>(secret, A(i-1))
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*/
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#include <stdio.h>
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#include <stdarg.h>
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#include <string.h>
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#include "internal/cryptlib.h"
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#include <openssl/evp.h>
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#include <openssl/kdf.h>
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#include "internal/evp_int.h"
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#include "kdf_local.h"
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static void kdf_tls1_prf_reset(EVP_KDF_IMPL *impl);
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static int tls1_prf_alg(const EVP_MD *md,
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const unsigned char *sec, size_t slen,
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const unsigned char *seed, size_t seed_len,
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unsigned char *out, size_t olen);
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#define TLS1_PRF_MAXBUF 1024
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/* TLS KDF kdf context structure */
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struct evp_kdf_impl_st {
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/* Digest to use for PRF */
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const EVP_MD *md;
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/* Secret value to use for PRF */
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unsigned char *sec;
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size_t seclen;
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/* Buffer of concatenated seed data */
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unsigned char seed[TLS1_PRF_MAXBUF];
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size_t seedlen;
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};
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static EVP_KDF_IMPL *kdf_tls1_prf_new(void)
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{
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EVP_KDF_IMPL *impl;
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if ((impl = OPENSSL_zalloc(sizeof(*impl))) == NULL)
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KDFerr(KDF_F_KDF_TLS1_PRF_NEW, ERR_R_MALLOC_FAILURE);
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return impl;
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}
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static void kdf_tls1_prf_free(EVP_KDF_IMPL *impl)
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{
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kdf_tls1_prf_reset(impl);
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OPENSSL_free(impl);
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}
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static void kdf_tls1_prf_reset(EVP_KDF_IMPL *impl)
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{
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OPENSSL_clear_free(impl->sec, impl->seclen);
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OPENSSL_cleanse(impl->seed, impl->seedlen);
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memset(impl, 0, sizeof(*impl));
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}
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static int kdf_tls1_prf_ctrl(EVP_KDF_IMPL *impl, int cmd, va_list args)
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{
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const unsigned char *p;
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size_t len;
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const EVP_MD *md;
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switch (cmd) {
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case EVP_KDF_CTRL_SET_MD:
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md = va_arg(args, const EVP_MD *);
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if (md == NULL)
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return 0;
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impl->md = md;
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return 1;
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case EVP_KDF_CTRL_SET_TLS_SECRET:
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p = va_arg(args, const unsigned char *);
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len = va_arg(args, size_t);
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OPENSSL_clear_free(impl->sec, impl->seclen);
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impl->sec = OPENSSL_memdup(p, len);
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if (impl->sec == NULL)
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return 0;
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impl->seclen = len;
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return 1;
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case EVP_KDF_CTRL_RESET_TLS_SEED:
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OPENSSL_cleanse(impl->seed, impl->seedlen);
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impl->seedlen = 0;
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return 1;
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case EVP_KDF_CTRL_ADD_TLS_SEED:
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p = va_arg(args, const unsigned char *);
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len = va_arg(args, size_t);
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if (len == 0 || p == NULL)
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return 1;
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if (len > (TLS1_PRF_MAXBUF - impl->seedlen))
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return 0;
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memcpy(impl->seed + impl->seedlen, p, len);
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impl->seedlen += len;
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return 1;
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default:
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return -2;
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}
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}
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static int kdf_tls1_prf_ctrl_str(EVP_KDF_IMPL *impl,
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const char *type, const char *value)
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{
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if (value == NULL) {
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KDFerr(KDF_F_KDF_TLS1_PRF_CTRL_STR, KDF_R_VALUE_MISSING);
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return 0;
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}
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if (strcmp(type, "digest") == 0)
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return kdf_md2ctrl(impl, kdf_tls1_prf_ctrl, EVP_KDF_CTRL_SET_MD, value);
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if (strcmp(type, "secret") == 0)
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return kdf_str2ctrl(impl, kdf_tls1_prf_ctrl,
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EVP_KDF_CTRL_SET_TLS_SECRET, value);
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if (strcmp(type, "hexsecret") == 0)
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return kdf_hex2ctrl(impl, kdf_tls1_prf_ctrl,
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EVP_KDF_CTRL_SET_TLS_SECRET, value);
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if (strcmp(type, "seed") == 0)
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return kdf_str2ctrl(impl, kdf_tls1_prf_ctrl, EVP_KDF_CTRL_ADD_TLS_SEED,
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value);
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if (strcmp(type, "hexseed") == 0)
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return kdf_hex2ctrl(impl, kdf_tls1_prf_ctrl, EVP_KDF_CTRL_ADD_TLS_SEED,
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value);
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return -2;
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}
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static int kdf_tls1_prf_derive(EVP_KDF_IMPL *impl, unsigned char *key,
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size_t keylen)
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{
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if (impl->md == NULL) {
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KDFerr(KDF_F_KDF_TLS1_PRF_DERIVE, KDF_R_MISSING_MESSAGE_DIGEST);
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return 0;
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}
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if (impl->sec == NULL) {
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KDFerr(KDF_F_KDF_TLS1_PRF_DERIVE, KDF_R_MISSING_SECRET);
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return 0;
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}
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if (impl->seedlen == 0) {
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KDFerr(KDF_F_KDF_TLS1_PRF_DERIVE, KDF_R_MISSING_SEED);
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return 0;
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}
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return tls1_prf_alg(impl->md, impl->sec, impl->seclen,
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impl->seed, impl->seedlen,
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key, keylen);
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}
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const EVP_KDF tls1_prf_kdf_meth = {
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EVP_KDF_TLS1_PRF,
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kdf_tls1_prf_new,
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kdf_tls1_prf_free,
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kdf_tls1_prf_reset,
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kdf_tls1_prf_ctrl,
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kdf_tls1_prf_ctrl_str,
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NULL,
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kdf_tls1_prf_derive
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};
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/*
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* Refer to "The TLS Protocol Version 1.0" Section 5
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* (https://tools.ietf.org/html/rfc2246#section-5) and
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* "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
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* (https://tools.ietf.org/html/rfc5246#section-5).
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*
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* P_<hash> is an expansion function that uses a single hash function to expand
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* a secret and seed into an arbitrary quantity of output:
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*
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* P_<hash>(secret, seed) = HMAC_<hash>(secret, A(1) + seed) +
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* HMAC_<hash>(secret, A(2) + seed) +
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* HMAC_<hash>(secret, A(3) + seed) + ...
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*
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* where + indicates concatenation. P_<hash> can be iterated as many times as
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* is necessary to produce the required quantity of data.
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*
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* A(i) is defined as:
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* A(0) = seed
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* A(i) = HMAC_<hash>(secret, A(i-1))
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*/
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static int tls1_prf_P_hash(const EVP_MD *md,
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const unsigned char *sec, size_t sec_len,
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const unsigned char *seed, size_t seed_len,
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unsigned char *out, size_t olen)
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{
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size_t chunk;
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EVP_MAC_CTX *ctx = NULL, *ctx_Ai = NULL, *ctx_init = NULL;
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unsigned char Ai[EVP_MAX_MD_SIZE];
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size_t Ai_len;
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int ret = 0;
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ctx_init = EVP_MAC_CTX_new_id(EVP_MAC_HMAC);
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if (ctx_init == NULL)
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goto err;
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if (EVP_MAC_ctrl(ctx_init, EVP_MAC_CTRL_SET_FLAGS, EVP_MD_CTX_FLAG_NON_FIPS_ALLOW) != 1)
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goto err;
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if (EVP_MAC_ctrl(ctx_init, EVP_MAC_CTRL_SET_MD, md) != 1)
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goto err;
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if (EVP_MAC_ctrl(ctx_init, EVP_MAC_CTRL_SET_KEY, sec, sec_len) != 1)
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goto err;
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if (!EVP_MAC_init(ctx_init))
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goto err;
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chunk = EVP_MAC_size(ctx_init);
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if (chunk == 0)
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goto err;
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/* A(0) = seed */
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ctx_Ai = EVP_MAC_CTX_dup(ctx_init);
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if (ctx_Ai == NULL)
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goto err;
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if (seed != NULL && !EVP_MAC_update(ctx_Ai, seed, seed_len))
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goto err;
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for (;;) {
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/* calc: A(i) = HMAC_<hash>(secret, A(i-1)) */
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if (!EVP_MAC_final(ctx_Ai, Ai, &Ai_len))
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goto err;
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EVP_MAC_CTX_free(ctx_Ai);
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ctx_Ai = NULL;
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/* calc next chunk: HMAC_<hash>(secret, A(i) + seed) */
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ctx = EVP_MAC_CTX_dup(ctx_init);
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if (ctx == NULL)
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goto err;
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if (!EVP_MAC_update(ctx, Ai, Ai_len))
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goto err;
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/* save state for calculating next A(i) value */
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if (olen > chunk) {
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ctx_Ai = EVP_MAC_CTX_dup(ctx);
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if (ctx_Ai == NULL)
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goto err;
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}
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if (seed != NULL && !EVP_MAC_update(ctx, seed, seed_len))
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goto err;
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if (olen <= chunk) {
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/* last chunk - use Ai as temp bounce buffer */
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if (!EVP_MAC_final(ctx, Ai, &Ai_len))
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goto err;
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memcpy(out, Ai, olen);
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break;
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}
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if (!EVP_MAC_final(ctx, out, NULL))
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goto err;
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EVP_MAC_CTX_free(ctx);
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ctx = NULL;
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out += chunk;
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olen -= chunk;
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}
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ret = 1;
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err:
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EVP_MAC_CTX_free(ctx);
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EVP_MAC_CTX_free(ctx_Ai);
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EVP_MAC_CTX_free(ctx_init);
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OPENSSL_cleanse(Ai, sizeof(Ai));
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return ret;
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}
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/*
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* Refer to "The TLS Protocol Version 1.0" Section 5
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* (https://tools.ietf.org/html/rfc2246#section-5) and
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* "The Transport Layer Security (TLS) Protocol Version 1.2" Section 5
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* (https://tools.ietf.org/html/rfc5246#section-5).
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*
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* For TLS v1.0 and TLS v1.1:
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*
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* PRF(secret, label, seed) = P_MD5(S1, label + seed) XOR
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* P_SHA-1(S2, label + seed)
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*
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* S1 is taken from the first half of the secret, S2 from the second half.
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*
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* L_S = length in bytes of secret;
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* L_S1 = L_S2 = ceil(L_S / 2);
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*
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* For TLS v1.2:
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*
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* PRF(secret, label, seed) = P_<hash>(secret, label + seed)
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*/
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static int tls1_prf_alg(const EVP_MD *md,
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const unsigned char *sec, size_t slen,
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const unsigned char *seed, size_t seed_len,
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unsigned char *out, size_t olen)
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{
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if (EVP_MD_type(md) == NID_md5_sha1) {
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/* TLS v1.0 and TLS v1.1 */
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size_t i;
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unsigned char *tmp;
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/* calc: L_S1 = L_S2 = ceil(L_S / 2) */
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size_t L_S1 = (slen + 1) / 2;
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size_t L_S2 = L_S1;
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if (!tls1_prf_P_hash(EVP_md5(), sec, L_S1,
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seed, seed_len, out, olen))
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return 0;
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if ((tmp = OPENSSL_malloc(olen)) == NULL) {
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KDFerr(KDF_F_TLS1_PRF_ALG, ERR_R_MALLOC_FAILURE);
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return 0;
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}
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if (!tls1_prf_P_hash(EVP_sha1(), sec + slen - L_S2, L_S2,
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seed, seed_len, tmp, olen)) {
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OPENSSL_clear_free(tmp, olen);
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return 0;
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}
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for (i = 0; i < olen; i++)
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out[i] ^= tmp[i];
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OPENSSL_clear_free(tmp, olen);
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return 1;
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}
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/* TLS v1.2 */
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if (!tls1_prf_P_hash(md, sec, slen, seed, seed_len, out, olen))
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return 0;
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return 1;
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}
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