2018-02-07 02:06:50 +00:00
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/* $OpenBSD: ssh-dss.c,v 1.37 2018/02/07 02:06:51 jsing Exp $ */
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2000-04-16 01:52:47 +00:00
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/*
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* Copyright (c) 2000 Markus Friedl. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "includes.h"
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2001-01-22 05:34:40 +00:00
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2015-01-14 15:21:31 +00:00
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#ifdef WITH_OPENSSL
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2006-08-05 02:39:39 +00:00
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#include <sys/types.h>
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2001-01-22 05:34:40 +00:00
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#include <openssl/bn.h>
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2014-08-19 01:32:34 +00:00
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#include <openssl/dsa.h>
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2001-01-22 05:34:40 +00:00
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#include <openssl/evp.h>
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2000-04-16 01:52:47 +00:00
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2006-09-01 05:38:36 +00:00
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#include <stdarg.h>
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2006-07-24 04:13:33 +00:00
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#include <string.h>
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2014-07-02 05:28:02 +00:00
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#include "sshbuf.h"
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2000-04-16 01:52:47 +00:00
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#include "compat.h"
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2014-07-02 05:28:02 +00:00
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#include "ssherr.h"
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2014-01-09 23:58:53 +00:00
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#include "digest.h"
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2014-07-02 05:28:02 +00:00
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#define SSHKEY_INTERNAL
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#include "sshkey.h"
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2000-04-16 01:52:47 +00:00
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2018-09-13 02:13:50 +00:00
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#include "openbsd-compat/openssl-compat.h"
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2000-04-16 01:52:47 +00:00
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#define INTBLOB_LEN 20
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#define SIGBLOB_LEN (2*INTBLOB_LEN)
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int
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2014-07-02 05:28:02 +00:00
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ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
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const u_char *data, size_t datalen, u_int compat)
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2000-04-16 01:52:47 +00:00
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{
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2014-07-02 05:28:02 +00:00
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DSA_SIG *sig = NULL;
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2018-09-13 02:08:33 +00:00
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const BIGNUM *sig_r, *sig_s;
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2014-01-09 23:58:53 +00:00
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u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
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2014-07-02 05:28:02 +00:00
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size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
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struct sshbuf *b = NULL;
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int ret = SSH_ERR_INVALID_ARGUMENT;
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if (lenp != NULL)
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*lenp = 0;
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if (sigp != NULL)
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*sigp = NULL;
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if (key == NULL || key->dsa == NULL ||
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sshkey_type_plain(key->type) != KEY_DSA)
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return SSH_ERR_INVALID_ARGUMENT;
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if (dlen == 0)
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return SSH_ERR_INTERNAL_ERROR;
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if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
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digest, sizeof(digest))) != 0)
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goto out;
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if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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2001-06-09 01:36:21 +00:00
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}
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2000-04-16 01:52:47 +00:00
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2018-09-13 02:08:33 +00:00
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DSA_SIG_get0(sig, &sig_r, &sig_s);
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rlen = BN_num_bytes(sig_r);
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slen = BN_num_bytes(sig_s);
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2000-04-16 01:52:47 +00:00
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if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
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2014-07-02 05:28:02 +00:00
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ret = SSH_ERR_INTERNAL_ERROR;
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goto out;
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2000-04-16 01:52:47 +00:00
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}
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2014-02-04 00:20:14 +00:00
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explicit_bzero(sigblob, SIGBLOB_LEN);
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2018-09-13 02:08:33 +00:00
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BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
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BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
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2000-04-16 01:52:47 +00:00
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2018-01-23 05:27:21 +00:00
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if ((b = sshbuf_new()) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
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(ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
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goto out;
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len = sshbuf_len(b);
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if (sigp != NULL) {
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if ((*sigp = malloc(len)) == NULL) {
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2014-07-02 05:28:02 +00:00
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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2018-01-23 05:27:21 +00:00
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memcpy(*sigp, sshbuf_ptr(b), len);
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2000-04-16 01:52:47 +00:00
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}
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2018-01-23 05:27:21 +00:00
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if (lenp != NULL)
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*lenp = len;
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ret = 0;
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2014-07-02 05:28:02 +00:00
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out:
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explicit_bzero(digest, sizeof(digest));
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2018-02-07 02:06:50 +00:00
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DSA_SIG_free(sig);
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2015-12-11 04:21:11 +00:00
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sshbuf_free(b);
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2014-07-02 05:28:02 +00:00
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return ret;
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2000-04-16 01:52:47 +00:00
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}
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2014-07-02 05:28:02 +00:00
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2000-04-16 01:52:47 +00:00
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int
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2014-07-02 05:28:02 +00:00
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ssh_dss_verify(const struct sshkey *key,
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const u_char *signature, size_t signaturelen,
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const u_char *data, size_t datalen, u_int compat)
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2000-04-16 01:52:47 +00:00
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{
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2014-07-02 05:28:02 +00:00
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DSA_SIG *sig = NULL;
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2018-09-13 02:08:33 +00:00
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BIGNUM *sig_r = NULL, *sig_s = NULL;
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2014-07-02 05:28:02 +00:00
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u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
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size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
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int ret = SSH_ERR_INTERNAL_ERROR;
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struct sshbuf *b = NULL;
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char *ktype = NULL;
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if (key == NULL || key->dsa == NULL ||
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2016-04-21 06:08:02 +00:00
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sshkey_type_plain(key->type) != KEY_DSA ||
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signature == NULL || signaturelen == 0)
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2014-07-02 05:28:02 +00:00
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return SSH_ERR_INVALID_ARGUMENT;
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if (dlen == 0)
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return SSH_ERR_INTERNAL_ERROR;
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2000-04-16 01:52:47 +00:00
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/* fetch signature */
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2018-01-23 05:27:21 +00:00
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if ((b = sshbuf_from(signature, signaturelen)) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
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sshbuf_get_string(b, &sigblob, &len) != 0) {
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ret = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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if (strcmp("ssh-dss", ktype) != 0) {
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ret = SSH_ERR_KEY_TYPE_MISMATCH;
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goto out;
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}
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if (sshbuf_len(b) != 0) {
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ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
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goto out;
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2000-04-16 01:52:47 +00:00
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}
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if (len != SIGBLOB_LEN) {
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2014-07-02 05:28:02 +00:00
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ret = SSH_ERR_INVALID_FORMAT;
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goto out;
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2000-04-16 01:52:47 +00:00
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}
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/* parse signature */
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2014-07-02 05:28:02 +00:00
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if ((sig = DSA_SIG_new()) == NULL ||
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2018-09-13 02:08:33 +00:00
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(sig_r = BN_new()) == NULL ||
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(sig_s = BN_new()) == NULL) {
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2014-07-02 05:28:02 +00:00
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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2018-09-13 02:08:33 +00:00
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if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
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(BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
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2014-07-02 05:28:02 +00:00
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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2018-09-13 02:08:33 +00:00
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if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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sig_r = sig_s = NULL; /* transferred */
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2001-02-05 12:42:17 +00:00
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2000-04-29 13:57:08 +00:00
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/* sha1 the data */
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2014-07-02 05:28:02 +00:00
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if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
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digest, sizeof(digest))) != 0)
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goto out;
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switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
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case 1:
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ret = 0;
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break;
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case 0:
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ret = SSH_ERR_SIGNATURE_INVALID;
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goto out;
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default:
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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2014-01-09 23:58:53 +00:00
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}
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2000-04-16 01:52:47 +00:00
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2014-07-02 05:28:02 +00:00
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out:
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2014-02-04 00:20:14 +00:00
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explicit_bzero(digest, sizeof(digest));
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2018-02-07 02:06:50 +00:00
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DSA_SIG_free(sig);
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2018-09-13 02:08:33 +00:00
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BN_clear_free(sig_r);
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BN_clear_free(sig_s);
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2015-12-11 04:21:11 +00:00
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sshbuf_free(b);
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2015-12-10 17:08:40 +00:00
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free(ktype);
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2014-07-02 05:28:02 +00:00
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if (sigblob != NULL) {
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explicit_bzero(sigblob, len);
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free(sigblob);
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}
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2000-04-16 01:52:47 +00:00
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return ret;
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}
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2015-01-14 15:21:31 +00:00
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#endif /* WITH_OPENSSL */
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