324 lines
6.3 KiB
C
Executable file
324 lines
6.3 KiB
C
Executable file
/* $OpenBSD: tls13_key_share.c,v 1.6 2020/04/18 14:07:56 jsing Exp $ */
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/*
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* Copyright (c) 2020 Joel Sing <jsing@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <stdlib.h>
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#include <openssl/curve25519.h>
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#include "bytestring.h"
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#include "ssl_locl.h"
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#include "tls13_internal.h"
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struct tls13_key_share {
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int nid;
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uint16_t group_id;
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EC_KEY *ecdhe;
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EC_KEY *ecdhe_peer;
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uint8_t *x25519_public;
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uint8_t *x25519_private;
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uint8_t *x25519_peer_public;
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};
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struct tls13_key_share *
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tls13_key_share_new(uint16_t group_id)
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{
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struct tls13_key_share *ks;
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int nid;
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if ((nid = tls1_ec_curve_id2nid(group_id)) == 0)
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return NULL;
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if ((ks = calloc(1, sizeof(struct tls13_key_share))) == NULL)
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return NULL;
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ks->group_id = group_id;
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ks->nid = nid;
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return ks;
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}
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struct tls13_key_share *
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tls13_key_share_new_nid(int nid)
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{
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uint16_t group_id;
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if ((group_id = tls1_ec_nid2curve_id(nid)) == 0)
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return NULL;
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return tls13_key_share_new(group_id);
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}
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void
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tls13_key_share_free(struct tls13_key_share *ks)
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{
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if (ks == NULL)
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return;
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EC_KEY_free(ks->ecdhe);
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EC_KEY_free(ks->ecdhe_peer);
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freezero(ks->x25519_public, X25519_KEY_LENGTH);
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freezero(ks->x25519_private, X25519_KEY_LENGTH);
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freezero(ks->x25519_peer_public, X25519_KEY_LENGTH);
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freezero(ks, sizeof(*ks));
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}
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uint16_t
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tls13_key_share_group(struct tls13_key_share *ks)
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{
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return ks->group_id;
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}
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int
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tls13_key_share_peer_pkey(struct tls13_key_share *ks, EVP_PKEY *pkey)
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{
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if (ks->nid == NID_X25519 && ks->x25519_peer_public != NULL) {
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if (!ssl_kex_dummy_ecdhe_x25519(pkey))
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return 0;
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} else if (ks->ecdhe_peer != NULL) {
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if (!EVP_PKEY_set1_EC_KEY(pkey, ks->ecdhe_peer))
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return 0;
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} else {
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return 0;
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}
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return 1;
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}
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static int
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tls13_key_share_generate_ecdhe_ecp(struct tls13_key_share *ks)
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{
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EC_KEY *ecdhe = NULL;
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int ret = 0;
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if (ks->ecdhe != NULL)
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goto err;
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if ((ecdhe = EC_KEY_new()) == NULL)
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goto err;
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if (!ssl_kex_generate_ecdhe_ecp(ecdhe, ks->nid))
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goto err;
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ks->ecdhe = ecdhe;
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ecdhe = NULL;
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ret = 1;
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err:
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EC_KEY_free(ecdhe);
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return ret;
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}
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static int
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tls13_key_share_generate_x25519(struct tls13_key_share *ks)
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{
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uint8_t *public = NULL, *private = NULL;
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int ret = 0;
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if (ks->x25519_public != NULL || ks->x25519_private != NULL)
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goto err;
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if ((public = calloc(1, X25519_KEY_LENGTH)) == NULL)
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goto err;
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if ((private = calloc(1, X25519_KEY_LENGTH)) == NULL)
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goto err;
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X25519_keypair(public, private);
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ks->x25519_public = public;
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ks->x25519_private = private;
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public = NULL;
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private = NULL;
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ret = 1;
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err:
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freezero(public, X25519_KEY_LENGTH);
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freezero(private, X25519_KEY_LENGTH);
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return ret;
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}
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int
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tls13_key_share_generate(struct tls13_key_share *ks)
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{
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if (ks->nid == NID_X25519)
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return tls13_key_share_generate_x25519(ks);
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return tls13_key_share_generate_ecdhe_ecp(ks);
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}
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static int
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tls13_key_share_public_ecdhe_ecp(struct tls13_key_share *ks, CBB *cbb)
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{
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if (ks->ecdhe == NULL)
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return 0;
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return ssl_kex_public_ecdhe_ecp(ks->ecdhe, cbb);
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}
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static int
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tls13_key_share_public_x25519(struct tls13_key_share *ks, CBB *cbb)
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{
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if (ks->x25519_public == NULL)
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return 0;
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return CBB_add_bytes(cbb, ks->x25519_public, X25519_KEY_LENGTH);
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}
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int
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tls13_key_share_public(struct tls13_key_share *ks, CBB *cbb)
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{
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CBB key_exchange;
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if (!CBB_add_u16(cbb, ks->group_id))
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goto err;
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if (!CBB_add_u16_length_prefixed(cbb, &key_exchange))
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goto err;
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if (ks->nid == NID_X25519) {
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if (!tls13_key_share_public_x25519(ks, &key_exchange))
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goto err;
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} else {
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if (!tls13_key_share_public_ecdhe_ecp(ks, &key_exchange))
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goto err;
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}
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if (!CBB_flush(cbb))
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goto err;
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return 1;
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err:
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return 0;
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}
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static int
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tls13_key_share_peer_public_ecdhe_ecp(struct tls13_key_share *ks, CBS *cbs)
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{
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EC_KEY *ecdhe = NULL;
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int ret = 0;
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if (ks->ecdhe_peer != NULL)
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goto err;
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if ((ecdhe = EC_KEY_new()) == NULL)
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goto err;
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if (!ssl_kex_peer_public_ecdhe_ecp(ecdhe, ks->nid, cbs))
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goto err;
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ks->ecdhe_peer = ecdhe;
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ecdhe = NULL;
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ret = 1;
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err:
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EC_KEY_free(ecdhe);
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return ret;
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}
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static int
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tls13_key_share_peer_public_x25519(struct tls13_key_share *ks, CBS *cbs)
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{
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size_t out_len;
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if (ks->x25519_peer_public != NULL)
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return 0;
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if (CBS_len(cbs) != X25519_KEY_LENGTH)
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return 0;
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return CBS_stow(cbs, &ks->x25519_peer_public, &out_len);
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}
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int
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tls13_key_share_peer_public(struct tls13_key_share *ks, uint16_t group,
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CBS *cbs)
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{
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if (ks->group_id != group)
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return 0;
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if (ks->nid == NID_X25519) {
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if (!tls13_key_share_peer_public_x25519(ks, cbs))
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return 0;
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} else {
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if (!tls13_key_share_peer_public_ecdhe_ecp(ks, cbs))
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return 0;
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}
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return 1;
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}
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static int
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tls13_key_share_derive_ecdhe_ecp(struct tls13_key_share *ks,
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uint8_t **shared_key, size_t *shared_key_len)
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{
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if (ks->ecdhe == NULL || ks->ecdhe_peer == NULL)
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return 0;
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return ssl_kex_derive_ecdhe_ecp(ks->ecdhe, ks->ecdhe_peer,
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shared_key, shared_key_len);
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}
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static int
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tls13_key_share_derive_x25519(struct tls13_key_share *ks,
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uint8_t **shared_key, size_t *shared_key_len)
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{
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uint8_t *sk = NULL;
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int ret = 0;
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if (ks->x25519_private == NULL || ks->x25519_peer_public == NULL)
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goto err;
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if ((sk = calloc(1, X25519_KEY_LENGTH)) == NULL)
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goto err;
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if (!X25519(sk, ks->x25519_private, ks->x25519_peer_public))
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goto err;
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*shared_key = sk;
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*shared_key_len = X25519_KEY_LENGTH;
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sk = NULL;
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ret = 1;
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err:
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freezero(sk, X25519_KEY_LENGTH);
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return ret;
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}
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int
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tls13_key_share_derive(struct tls13_key_share *ks, uint8_t **shared_key,
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size_t *shared_key_len)
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{
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if (*shared_key != NULL)
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return 0;
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*shared_key_len = 0;
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if (ks->nid == NID_X25519)
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return tls13_key_share_derive_x25519(ks, shared_key,
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shared_key_len);
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return tls13_key_share_derive_ecdhe_ecp(ks, shared_key,
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shared_key_len);
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}
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