/*
* Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.
*
* Licensed under the OpenSSL license (the "License"). You may not use
* this file except in compliance with the License. You can obtain a copy
* in the file LICENSE in the source distribution or at
* https://www.openssl.org/source/license.html
*/
#include <stdlib.h>
#include "ssl_local.h"
#include "internal/cryptlib.h"
#include <openssl/evp.h>
#include <openssl/kdf.h>
#define TLS13_MAX_LABEL_LEN 249
/* Always filled with zeros */
static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
/*
* Given a |secret|; a |label| of length |labellen|; and |data| of length
* |datalen| (e.g. typically a hash of the handshake messages), derive a new
* secret |outlen| bytes long and store it in the location pointed to be |out|.
* The |data| value may be zero length. Any errors will be treated as fatal if
* |fatal| is set. Returns 1 on success 0 on failure.
*/
int tls13_hkdf_expand(SSL *s, const EVP_MD *md, const unsigned char *secret,
const unsigned char *label, size_t labellen,
const unsigned char *data, size_t datalen,
unsigned char *out, size_t outlen, int fatal)
{
#ifdef CHARSET_EBCDIC
static const unsigned char label_prefix[] = { 0x74, 0x6C, 0x73, 0x31, 0x33, 0x20, 0x00 };
#else
static const unsigned char label_prefix[] = "tls13 ";
#endif
EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
int ret;
size_t hkdflabellen;
size_t hashlen;
/*
* 2 bytes for length of derived secret + 1 byte for length of combined
* prefix and label + bytes for the label itself + 1 byte length of hash
* + bytes for the hash itself
*/
unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t)
+ (sizeof(label_prefix) - 1) + TLS13_MAX_LABEL_LEN
+ 1 + EVP_MAX_MD_SIZE];
WPACKET pkt;
if (pctx == NULL)
return 0;
if (labellen > TLS13_MAX_LABEL_LEN) {
if (fatal) {
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
ERR_R_INTERNAL_ERROR);
} else {
/*
* Probably we have been called from SSL_export_keying_material(),
* or SSL_export_keying_material_early().
*/
SSLerr(SSL_F_TLS13_HKDF_EXPAND, SSL_R_TLS_ILLEGAL_EXPORTER_LABEL);
}
EVP_PKEY_CTX_free(pctx);
return 0;
}
hashlen = EVP_MD_size(md);
if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
|| !WPACKET_put_bytes_u16(&pkt, outlen)
|| !WPACKET_start_sub_packet_u8(&pkt)
|| !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
|| !WPACKET_memcpy(&pkt, label, labellen)
|| !WPACKET_close(&pkt)
|| !WPACKET_sub_memcpy_u8(&pkt, data, (data == NULL) ? 0 : datalen)
|| !WPACKET_get_total_written(&pkt, &hkdflabellen)
|| !WPACKET_finish(&pkt)) {
EVP_PKEY_CTX_free(pctx);
WPACKET_cleanup(&pkt);
if (fatal)
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
ERR_R_INTERNAL_ERROR);
else
SSLerr(SSL_F_TLS13_HKDF_EXPAND, ERR_R_INTERNAL_ERROR);
return 0;
}
ret = EVP_PKEY_derive_init(pctx) <= 0
|| EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
<= 0
|| EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
|| EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
|| EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
|| EVP_PKEY_derive(pctx, out, &outlen) <= 0;
EVP_PKEY_CTX_free(pctx);
if (ret != 0) {
if (fatal)
SSLfatal(s, SSL_AD_INTERNAL_ERROR, SSL_F_TLS13_HKDF_EXPAND,
ERR_R_INTERNAL_ERROR);
else
SSLerr(SSL_F_TLS13_HKDF_EXPAND, ERR_R_INTERNAL_ERROR);
}
return ret == 0;
}
/*
* Given a |secret| generate a |key| of length |keylen| bytes. Returns 1 on
* success 0 on failure.
*/
int tls13_derive_key(SSL *s, const EVP_MD *md, const unsigned char *secret,
unsigned char *key, size_t keylen)
{
#ifdef CHARSET_EBCDIC
static const unsigned char keylabel[] ={ 0x6B, 0x65, 0x79, 0x00 };
#else
static const unsigned char keylabel[] = "key";
#endif
return tls13_hkdf_expand(s, md, secret, keylabel, sizeof(keylabel) - 1,
NULL, 0, key, keylen, 1);
}
/*
* Given a |secret| generate an |iv| of length |ivlen| bytes. Returns 1 on
* success 0 on failure.
*/
int tls13_derive_iv(SSL *s, const EVP_MD *md, const unsigned char *secret,
unsigned char *iv, size_t ivlen)
{
#ifdef CH