398 lines
13 KiB
C
398 lines
13 KiB
C
/*
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* Copyright 2016 The OpenSSL Project Authors. All Rights Reserved.
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*
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* Licensed under the OpenSSL license (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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#include <stdlib.h>
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#include "ssl_locl.h"
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#include <openssl/evp.h>
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#include <openssl/kdf.h>
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#define TLS13_MAX_LABEL_LEN 246
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/* Always filled with zeros */
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static const unsigned char default_zeros[EVP_MAX_MD_SIZE];
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/*
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* Given a |secret|; a |label| of length |labellen|; and a |hash| of the
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* handshake messages, derive a new secret |outlen| bytes long and store it in
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* the location pointed to be |out|. The |hash| value may be NULL. Returns 1 on
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* success 0 on failure.
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*/
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static int tls13_hkdf_expand(SSL *s, const unsigned char *secret,
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const unsigned char *label, size_t labellen,
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const unsigned char *hash,
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unsigned char *out, size_t outlen)
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{
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const unsigned char label_prefix[] = "TLS 1.3, ";
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const EVP_MD *md = ssl_handshake_md(s);
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EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
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int ret;
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size_t hkdflabellen;
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size_t hashlen;
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/*
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* 2 bytes for length of whole HkdfLabel + 1 byte for length of combined
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* prefix and label + bytes for the label itself + bytes for the hash
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*/
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unsigned char hkdflabel[sizeof(uint16_t) + sizeof(uint8_t) +
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+ sizeof(label_prefix) + TLS13_MAX_LABEL_LEN
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+ EVP_MAX_MD_SIZE];
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WPACKET pkt;
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if (pctx == NULL)
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return 0;
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hashlen = EVP_MD_size(md);
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if (!WPACKET_init_static_len(&pkt, hkdflabel, sizeof(hkdflabel), 0)
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|| !WPACKET_put_bytes_u16(&pkt, outlen)
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|| !WPACKET_start_sub_packet_u8(&pkt)
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|| !WPACKET_memcpy(&pkt, label_prefix, sizeof(label_prefix) - 1)
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|| !WPACKET_memcpy(&pkt, label, labellen)
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|| !WPACKET_close(&pkt)
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|| !WPACKET_sub_memcpy_u8(&pkt, hash, (hash == NULL) ? 0 : hashlen)
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|| !WPACKET_get_total_written(&pkt, &hkdflabellen)
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|| !WPACKET_finish(&pkt)) {
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WPACKET_cleanup(&pkt);
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return 0;
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}
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ret = EVP_PKEY_derive_init(pctx) <= 0
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|| EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXPAND_ONLY)
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<= 0
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|| EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
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|| EVP_PKEY_CTX_set1_hkdf_key(pctx, secret, hashlen) <= 0
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|| EVP_PKEY_CTX_add1_hkdf_info(pctx, hkdflabel, hkdflabellen) <= 0
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|| EVP_PKEY_derive(pctx, out, &outlen) <= 0;
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EVP_PKEY_CTX_free(pctx);
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return ret == 0;
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}
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/*
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* Given a input secret |insecret| and a |label| of length |labellen|, derive a
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* new |secret|. This will be the length of the current hash output size and
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* will be based on the current state of the handshake hashes. Returns 1 on
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* success 0 on failure.
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*/
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int tls13_derive_secret(SSL *s, const unsigned char *insecret,
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const unsigned char *label, size_t labellen,
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unsigned char *secret)
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{
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unsigned char hash[EVP_MAX_MD_SIZE];
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size_t hashlen;
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if (!ssl3_digest_cached_records(s, 1))
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return 0;
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if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen))
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return 0;
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return tls13_hkdf_expand(s, insecret, label, labellen, hash, secret,
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hashlen);
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}
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/*
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* Given a |secret| generate a |key| of length |keylen| bytes. Returns 1 on
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* success 0 on failure.
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*/
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int tls13_derive_key(SSL *s, const unsigned char *secret, unsigned char *key,
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size_t keylen)
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{
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static const unsigned char keylabel[] = "key";
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return tls13_hkdf_expand(s, secret, keylabel, sizeof(keylabel) - 1, NULL,
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key, keylen);
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}
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/*
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* Given a |secret| generate an |iv| of length |ivlen| bytes. Returns 1 on
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* success 0 on failure.
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*/
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int tls13_derive_iv(SSL *s, const unsigned char *secret, unsigned char *iv,
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size_t ivlen)
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{
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static const unsigned char ivlabel[] = "iv";
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return tls13_hkdf_expand(s, secret, ivlabel, sizeof(ivlabel) - 1, NULL,
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iv, ivlen);
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}
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static int tls13_derive_finishedkey(SSL *s, const unsigned char *secret,
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unsigned char *fin, size_t finlen)
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{
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static const unsigned char finishedlabel[] = "finished";
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return tls13_hkdf_expand(s, secret, finishedlabel,
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sizeof(finishedlabel) - 1, NULL, fin, finlen);
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}
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/*
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* Given the previous secret |prevsecret| and a new input secret |insecret| of
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* length |insecretlen|, generate a new secret and store it in the location
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* pointed to by |outsecret|. Returns 1 on success 0 on failure.
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*/
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static int tls13_generate_secret(SSL *s, const unsigned char *prevsecret,
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const unsigned char *insecret,
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size_t insecretlen,
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unsigned char *outsecret)
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{
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const EVP_MD *md = ssl_handshake_md(s);
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size_t mdlen, prevsecretlen;
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int ret;
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EVP_PKEY_CTX *pctx = EVP_PKEY_CTX_new_id(EVP_PKEY_HKDF, NULL);
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if (pctx == NULL)
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return 0;
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mdlen = EVP_MD_size(md);
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if (insecret == NULL) {
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insecret = default_zeros;
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insecretlen = mdlen;
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}
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if (prevsecret == NULL) {
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prevsecret = default_zeros;
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prevsecretlen = 0;
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} else {
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prevsecretlen = mdlen;
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}
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ret = EVP_PKEY_derive_init(pctx) <= 0
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|| EVP_PKEY_CTX_hkdf_mode(pctx, EVP_PKEY_HKDEF_MODE_EXTRACT_ONLY)
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<= 0
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|| EVP_PKEY_CTX_set_hkdf_md(pctx, md) <= 0
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|| EVP_PKEY_CTX_set1_hkdf_key(pctx, insecret, insecretlen) <= 0
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|| EVP_PKEY_CTX_set1_hkdf_salt(pctx, prevsecret, prevsecretlen)
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<= 0
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|| EVP_PKEY_derive(pctx, outsecret, &mdlen)
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<= 0;
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EVP_PKEY_CTX_free(pctx);
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return ret == 0;
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}
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/*
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* Given an input secret |insecret| of length |insecretlen| generate the early
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* secret. Returns 1 on success 0 on failure.
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*/
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int tls13_generate_early_secret(SSL *s, const unsigned char *insecret,
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size_t insecretlen)
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{
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return tls13_generate_secret(s, NULL, insecret, insecretlen,
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(unsigned char *)&s->early_secret);
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}
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/*
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* Given an input secret |insecret| of length |insecretlen| generate the
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* handshake secret. This requires the early secret to already have been
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* generated. Returns 1 on success 0 on failure.
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*/
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int tls13_generate_handshake_secret(SSL *s, const unsigned char *insecret,
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size_t insecretlen)
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{
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return tls13_generate_secret(s, s->early_secret, insecret, insecretlen,
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(unsigned char *)&s->handshake_secret);
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}
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/*
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* Given the handshake secret |prev| of length |prevlen| generate the master
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* secret and store its length in |*secret_size|. Returns 1 on success 0 on
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* failure.
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*/
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int tls13_generate_master_secret(SSL *s, unsigned char *out,
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unsigned char *prev, size_t prevlen,
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size_t *secret_size)
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{
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*secret_size = EVP_MD_size(ssl_handshake_md(s));
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return tls13_generate_secret(s, prev, NULL, 0, out);
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}
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/*
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* Generates the mac for the Finished message. Returns the length of the MAC or
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* 0 on error.
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*/
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size_t tls13_final_finish_mac(SSL *s, const char *str, size_t slen,
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unsigned char *out)
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{
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const EVP_MD *md = ssl_handshake_md(s);
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unsigned char hash[EVP_MAX_MD_SIZE];
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size_t hashlen, ret = 0;
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EVP_PKEY *key = NULL;
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EVP_MD_CTX *ctx = EVP_MD_CTX_new();
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if (!ssl_handshake_hash(s, hash, sizeof(hash), &hashlen))
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goto err;
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if (str == s->method->ssl3_enc->server_finished_label)
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key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
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s->server_finished_secret, hashlen);
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else
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key = EVP_PKEY_new_mac_key(EVP_PKEY_HMAC, NULL,
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s->client_finished_secret, hashlen);
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if (key == NULL
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|| ctx == NULL
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|| EVP_DigestSignInit(ctx, NULL, md, NULL, key) <= 0
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|| EVP_DigestSignUpdate(ctx, hash, hashlen) <= 0
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|| EVP_DigestSignFinal(ctx, out, &hashlen) <= 0)
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goto err;
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ret = hashlen;
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err:
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EVP_PKEY_free(key);
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EVP_MD_CTX_free(ctx);
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return ret;
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}
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/*
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* There isn't really a key block in TLSv1.3, but we still need this function
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* for initialising the cipher and hash. Returns 1 on success or 0 on failure.
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*/
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int tls13_setup_key_block(SSL *s)
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{
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const EVP_CIPHER *c;
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const EVP_MD *hash;
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int mac_type = NID_undef;
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s->session->cipher = s->s3->tmp.new_cipher;
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if (!ssl_cipher_get_evp
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(s->session, &c, &hash, &mac_type, NULL, NULL, 0)) {
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SSLerr(SSL_F_TLS13_SETUP_KEY_BLOCK, SSL_R_CIPHER_OR_HASH_UNAVAILABLE);
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return 0;
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}
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s->s3->tmp.new_sym_enc = c;
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s->s3->tmp.new_hash = hash;
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return 1;
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}
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int tls13_change_cipher_state(SSL *s, int which)
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{
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static const unsigned char client_handshake_traffic[] =
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"client handshake traffic secret";
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static const unsigned char client_application_traffic[] =
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"client application traffic secret";
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static const unsigned char server_handshake_traffic[] =
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"server handshake traffic secret";
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static const unsigned char server_application_traffic[] =
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"server application traffic secret";
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unsigned char key[EVP_MAX_KEY_LENGTH];
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unsigned char *iv;
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unsigned char secret[EVP_MAX_MD_SIZE];
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unsigned char *insecret;
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unsigned char *finsecret = NULL;
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EVP_CIPHER_CTX *ciph_ctx;
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const EVP_CIPHER *ciph = s->s3->tmp.new_sym_enc;
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size_t ivlen, keylen, finsecretlen = 0;
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const unsigned char *label;
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size_t labellen;
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int ret = 0;
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if (which & SSL3_CC_READ) {
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if (s->enc_read_ctx != NULL) {
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EVP_CIPHER_CTX_reset(s->enc_read_ctx);
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} else {
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s->enc_read_ctx = EVP_CIPHER_CTX_new();
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if (s->enc_read_ctx == NULL) {
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SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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}
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ciph_ctx = s->enc_read_ctx;
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iv = s->read_iv;
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RECORD_LAYER_reset_read_sequence(&s->rlayer);
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} else {
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if (s->enc_write_ctx != NULL) {
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EVP_CIPHER_CTX_reset(s->enc_write_ctx);
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} else {
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s->enc_write_ctx = EVP_CIPHER_CTX_new();
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if (s->enc_write_ctx == NULL) {
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SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_MALLOC_FAILURE);
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goto err;
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}
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}
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ciph_ctx = s->enc_write_ctx;
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iv = s->write_iv;
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RECORD_LAYER_reset_write_sequence(&s->rlayer);
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}
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if (((which & SSL3_CC_CLIENT) && (which & SSL3_CC_WRITE))
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|| ((which & SSL3_CC_SERVER) && (which & SSL3_CC_READ))) {
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if (which & SSL3_CC_HANDSHAKE) {
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insecret = s->handshake_secret;
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finsecret = s->client_finished_secret;
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finsecretlen = sizeof(s->client_finished_secret);
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label = client_handshake_traffic;
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labellen = sizeof(client_handshake_traffic) - 1;
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} else {
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insecret = s->session->master_key;
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label = client_application_traffic;
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labellen = sizeof(client_application_traffic) - 1;
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}
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} else {
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if (which & SSL3_CC_HANDSHAKE) {
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insecret = s->handshake_secret;
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finsecret = s->server_finished_secret;
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finsecretlen = sizeof(s->server_finished_secret);
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label = server_handshake_traffic;
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labellen = sizeof(server_handshake_traffic) - 1;
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} else {
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insecret = s->session->master_key;
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label = server_application_traffic;
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labellen = sizeof(server_application_traffic) - 1;
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}
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}
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if (!tls13_derive_secret(s, insecret, label, labellen, secret)) {
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SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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/* TODO(size_t): convert me */
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keylen = EVP_CIPHER_key_length(ciph);
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ivlen = EVP_CIPHER_iv_length(ciph);
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if (!tls13_derive_key(s, secret, key, keylen)
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|| !tls13_derive_iv(s, secret, iv, ivlen)
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|| (finsecret != NULL && !tls13_derive_finishedkey(s, secret,
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finsecret,
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finsecretlen))) {
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SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_INTERNAL_ERROR);
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goto err;
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}
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if (EVP_CipherInit_ex(ciph_ctx, ciph, NULL, key, NULL,
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(which & SSL3_CC_WRITE)) <= 0) {
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SSLerr(SSL_F_TLS13_CHANGE_CIPHER_STATE, ERR_R_EVP_LIB);
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goto err;
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}
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#ifdef OPENSSL_SSL_TRACE_CRYPTO
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if (s->msg_callback) {
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int wh = which & SSL3_CC_WRITE ? TLS1_RT_CRYPTO_WRITE : 0;
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if (ciph->key_len)
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s->msg_callback(2, s->version, wh | TLS1_RT_CRYPTO_KEY,
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key, ciph->key_len, s, s->msg_callback_arg);
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wh |= TLS1_RT_CRYPTO_IV;
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s->msg_callback(2, s->version, wh, iv, ivlen, s,
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s->msg_callback_arg);
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}
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#endif
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ret = 1;
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err:
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OPENSSL_cleanse(secret, sizeof(secret));
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OPENSSL_cleanse(key, sizeof(key));
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return ret;
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}
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