mirror of
git://anongit.mindrot.org/openssh.git
synced 2024-12-24 02:42:25 +00:00
a70d92f236
better match ec25519-sk keys. Discussed with markus@ and Sebastian Kinne NB. if you are depending on security keys (already?) then make sure you update both your clients and servers. OpenBSD-Commit-ID: 53d88d8211f0dd02a7954d3af72017b1a79c0679
184 lines
5.7 KiB
C
184 lines
5.7 KiB
C
/* $OpenBSD: ssh-ecdsa-sk.c,v 1.2 2019/11/19 22:23:19 djm Exp $ */
|
|
/*
|
|
* Copyright (c) 2000 Markus Friedl. All rights reserved.
|
|
* Copyright (c) 2010 Damien Miller. All rights reserved.
|
|
* Copyright (c) 2019 Google Inc. All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
|
|
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
|
|
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
|
|
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
|
|
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
|
|
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
|
|
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
|
|
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
|
|
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
|
|
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*/
|
|
|
|
/* #define DEBUG_SK 1 */
|
|
|
|
#include "includes.h"
|
|
|
|
#ifdef ENABLE_SK
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <openssl/bn.h>
|
|
#include <openssl/ec.h>
|
|
#include <openssl/ecdsa.h>
|
|
#include <openssl/evp.h>
|
|
|
|
#include <string.h>
|
|
#include <stdio.h> /* needed for DEBUG_SK only */
|
|
|
|
#include "sshbuf.h"
|
|
#include "ssherr.h"
|
|
#include "digest.h"
|
|
#define SSHKEY_INTERNAL
|
|
#include "sshkey.h"
|
|
|
|
/* ARGSUSED */
|
|
int
|
|
ssh_ecdsa_sk_verify(const struct sshkey *key,
|
|
const u_char *signature, size_t signaturelen,
|
|
const u_char *data, size_t datalen, u_int compat)
|
|
{
|
|
ECDSA_SIG *sig = NULL;
|
|
BIGNUM *sig_r = NULL, *sig_s = NULL;
|
|
u_char sig_flags;
|
|
u_char msghash[32], apphash[32], sighash[32];
|
|
u_int sig_counter;
|
|
int ret = SSH_ERR_INTERNAL_ERROR;
|
|
struct sshbuf *b = NULL, *sigbuf = NULL, *original_signed = NULL;
|
|
char *ktype = NULL;
|
|
#ifdef DEBUG_SK
|
|
char *tmp = NULL;
|
|
#endif
|
|
|
|
if (key == NULL || key->ecdsa == NULL ||
|
|
sshkey_type_plain(key->type) != KEY_ECDSA_SK ||
|
|
signature == NULL || signaturelen == 0)
|
|
return SSH_ERR_INVALID_ARGUMENT;
|
|
|
|
if (key->ecdsa_nid != NID_X9_62_prime256v1)
|
|
return SSH_ERR_INTERNAL_ERROR;
|
|
|
|
/* fetch signature */
|
|
if ((b = sshbuf_from(signature, signaturelen)) == NULL)
|
|
return SSH_ERR_ALLOC_FAIL;
|
|
if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
|
|
sshbuf_froms(b, &sigbuf) != 0 ||
|
|
sshbuf_get_u8(b, &sig_flags) != 0 ||
|
|
sshbuf_get_u32(b, &sig_counter) != 0) {
|
|
ret = SSH_ERR_INVALID_FORMAT;
|
|
goto out;
|
|
}
|
|
if (strcmp(sshkey_ssh_name_plain(key), ktype) != 0) {
|
|
ret = SSH_ERR_KEY_TYPE_MISMATCH;
|
|
goto out;
|
|
}
|
|
if (sshbuf_len(b) != 0) {
|
|
ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
|
|
goto out;
|
|
}
|
|
|
|
/* parse signature */
|
|
if (sshbuf_get_bignum2(sigbuf, &sig_r) != 0 ||
|
|
sshbuf_get_bignum2(sigbuf, &sig_s) != 0) {
|
|
ret = SSH_ERR_INVALID_FORMAT;
|
|
goto out;
|
|
}
|
|
if ((sig = ECDSA_SIG_new()) == NULL) {
|
|
ret = SSH_ERR_ALLOC_FAIL;
|
|
goto out;
|
|
}
|
|
if (!ECDSA_SIG_set0(sig, sig_r, sig_s)) {
|
|
ret = SSH_ERR_LIBCRYPTO_ERROR;
|
|
goto out;
|
|
}
|
|
#ifdef DEBUG_SK
|
|
fprintf(stderr, "%s: sig_r: %s\n", __func__, (tmp = BN_bn2hex(sig_r)));
|
|
free(tmp);
|
|
fprintf(stderr, "%s: sig_s: %s\n", __func__, (tmp = BN_bn2hex(sig_s)));
|
|
free(tmp);
|
|
fprintf(stderr, "%s: sig_flags = 0x%02x, sig_counter = %u\n",
|
|
__func__, sig_flags, sig_counter);
|
|
#endif
|
|
sig_r = sig_s = NULL; /* transferred */
|
|
|
|
if (sshbuf_len(sigbuf) != 0) {
|
|
ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
|
|
goto out;
|
|
}
|
|
|
|
/* Reconstruct data that was supposedly signed */
|
|
if ((original_signed = sshbuf_new()) == NULL)
|
|
return SSH_ERR_ALLOC_FAIL;
|
|
if ((ret = ssh_digest_memory(SSH_DIGEST_SHA256, data, datalen,
|
|
msghash, sizeof(msghash))) != 0)
|
|
goto out;
|
|
/* Application value is hashed before signature */
|
|
if ((ret = ssh_digest_memory(SSH_DIGEST_SHA256, key->sk_application,
|
|
strlen(key->sk_application), apphash, sizeof(apphash))) != 0)
|
|
goto out;
|
|
#ifdef DEBUG_SK
|
|
fprintf(stderr, "%s: hashed message:\n", __func__);
|
|
sshbuf_dump_data(msghash, sizeof(msghash), stderr);
|
|
#endif
|
|
if ((ret = sshbuf_put(original_signed,
|
|
apphash, sizeof(apphash))) != 0 ||
|
|
(ret = sshbuf_put_u8(original_signed, sig_flags)) != 0 ||
|
|
(ret = sshbuf_put_u32(original_signed, sig_counter)) != 0 ||
|
|
(ret = sshbuf_put(original_signed, msghash, sizeof(msghash))) != 0)
|
|
goto out;
|
|
/* Signature is over H(original_signed) */
|
|
if ((ret = ssh_digest_buffer(SSH_DIGEST_SHA256, original_signed,
|
|
sighash, sizeof(sighash))) != 0)
|
|
goto out;
|
|
#ifdef DEBUG_SK
|
|
fprintf(stderr, "%s: signed buf:\n", __func__);
|
|
sshbuf_dump(original_signed, stderr);
|
|
fprintf(stderr, "%s: signed hash:\n", __func__);
|
|
sshbuf_dump_data(sighash, sizeof(sighash), stderr);
|
|
#endif
|
|
|
|
/* Verify it */
|
|
switch (ECDSA_do_verify(sighash, sizeof(sighash), sig, key->ecdsa)) {
|
|
case 1:
|
|
ret = 0;
|
|
break;
|
|
case 0:
|
|
ret = SSH_ERR_SIGNATURE_INVALID;
|
|
goto out;
|
|
default:
|
|
ret = SSH_ERR_LIBCRYPTO_ERROR;
|
|
goto out;
|
|
}
|
|
|
|
out:
|
|
explicit_bzero(&sig_flags, sizeof(sig_flags));
|
|
explicit_bzero(&sig_counter, sizeof(sig_counter));
|
|
explicit_bzero(msghash, sizeof(msghash));
|
|
explicit_bzero(sighash, sizeof(msghash));
|
|
explicit_bzero(apphash, sizeof(apphash));
|
|
sshbuf_free(original_signed);
|
|
sshbuf_free(sigbuf);
|
|
sshbuf_free(b);
|
|
ECDSA_SIG_free(sig);
|
|
BN_clear_free(sig_r);
|
|
BN_clear_free(sig_s);
|
|
free(ktype);
|
|
return ret;
|
|
}
|
|
#endif /* ENABLE_SK */
|