2017-01-31 13:29:48 +01:00
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/* $OpenBSD: ssh-dss.c,v 1.35 2016/04/21 06:08:02 djm Exp $ */
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2001-05-04 05:57:05 +02:00
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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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2006-09-30 15:29:51 +02:00
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2015-07-02 15:15:34 +02:00
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#ifdef WITH_OPENSSL
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2006-09-30 15:29:51 +02:00
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#include <sys/types.h>
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2001-05-04 05:57:05 +02:00
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#include <openssl/bn.h>
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2015-01-05 17:09:55 +01:00
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#include <openssl/dsa.h>
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2001-05-04 05:57:05 +02:00
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#include <openssl/evp.h>
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2006-09-30 15:29:51 +02:00
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#include <stdarg.h>
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#include <string.h>
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2015-01-05 17:09:55 +01:00
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#include "sshbuf.h"
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2001-05-04 05:57:05 +02:00
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#include "compat.h"
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2015-01-05 17:09:55 +01:00
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#include "ssherr.h"
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2014-01-30 11:56:49 +01:00
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#include "digest.h"
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2015-01-05 17:09:55 +01:00
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#define SSHKEY_INTERNAL
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#include "sshkey.h"
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2001-05-04 05:57:05 +02:00
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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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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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{
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2015-01-05 17:09:55 +01:00
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DSA_SIG *sig = NULL;
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2014-01-30 11:56:49 +01:00
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u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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}
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rlen = BN_num_bytes(sig->r);
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slen = BN_num_bytes(sig->s);
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if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
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2015-01-05 17:09:55 +01:00
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ret = SSH_ERR_INTERNAL_ERROR;
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goto out;
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2001-05-04 05:57:05 +02:00
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}
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2014-03-22 16:23:38 +01:00
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explicit_bzero(sigblob, SIGBLOB_LEN);
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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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2015-01-05 17:09:55 +01:00
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if (compat & SSH_BUG_SIGBLOB) {
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2002-10-29 10:43:00 +01:00
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if (sigp != NULL) {
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2015-01-05 17:09:55 +01:00
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if ((*sigp = malloc(SIGBLOB_LEN)) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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2002-10-29 10:43:00 +01:00
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memcpy(*sigp, sigblob, SIGBLOB_LEN);
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}
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2015-01-05 17:09:55 +01:00
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if (lenp != NULL)
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*lenp = SIGBLOB_LEN;
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ret = 0;
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2001-05-04 05:57:05 +02:00
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} else {
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/* ietf-drafts */
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2015-01-05 17:09:55 +01:00
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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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2002-10-29 10:43:00 +01:00
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if (sigp != NULL) {
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2015-01-05 17:09:55 +01:00
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if ((*sigp = malloc(len)) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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memcpy(*sigp, sshbuf_ptr(b), len);
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2002-10-29 10:43:00 +01:00
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}
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2015-01-05 17:09:55 +01:00
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if (lenp != NULL)
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*lenp = len;
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ret = 0;
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2001-05-04 05:57:05 +02:00
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}
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2015-01-05 17:09:55 +01:00
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out:
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explicit_bzero(digest, sizeof(digest));
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if (sig != NULL)
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DSA_SIG_free(sig);
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2016-03-10 21:10:25 +01:00
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sshbuf_free(b);
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2015-01-05 17:09:55 +01:00
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return ret;
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2001-05-04 05:57:05 +02:00
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}
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2015-01-05 17:09:55 +01:00
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2001-05-04 05:57:05 +02:00
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int
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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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{
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2015-01-05 17:09:55 +01:00
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DSA_SIG *sig = NULL;
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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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2017-01-31 13:29:48 +01:00
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sshkey_type_plain(key->type) != KEY_DSA ||
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signature == NULL || signaturelen == 0)
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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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/* fetch signature */
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2015-01-05 17:09:55 +01:00
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if (compat & SSH_BUG_SIGBLOB) {
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if ((sigblob = malloc(signaturelen)) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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2004-02-26 11:38:49 +01:00
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memcpy(sigblob, signature, signaturelen);
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2001-05-04 05:57:05 +02:00
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len = signaturelen;
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} else {
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/* ietf-drafts */
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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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if (strcmp("ssh-dss", ktype) != 0) {
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2015-01-05 17:09:55 +01:00
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ret = SSH_ERR_KEY_TYPE_MISMATCH;
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goto out;
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2001-05-04 05:57:05 +02:00
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}
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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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}
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}
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if (len != SIGBLOB_LEN) {
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2015-01-05 17:09:55 +01:00
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ret = SSH_ERR_INVALID_FORMAT;
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goto out;
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2001-05-04 05:57:05 +02:00
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}
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/* parse signature */
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2015-01-05 17:09:55 +01:00
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if ((sig = DSA_SIG_new()) == NULL ||
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(sig->r = BN_new()) == NULL ||
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(sig->s = BN_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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2006-11-10 17:39:21 +01:00
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if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) ||
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2015-01-05 17:09:55 +01:00
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(BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL)) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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2001-05-04 05:57:05 +02:00
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/* sha1 the data */
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2015-01-05 17:09:55 +01:00
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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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2014-01-30 11:56:49 +01:00
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}
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2001-05-04 05:57:05 +02:00
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2015-01-05 17:09:55 +01:00
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out:
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2014-03-22 16:23:38 +01:00
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explicit_bzero(digest, sizeof(digest));
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2015-01-05 17:09:55 +01:00
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if (sig != NULL)
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DSA_SIG_free(sig);
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2016-03-10 21:10:25 +01:00
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sshbuf_free(b);
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free(ktype);
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2015-01-05 17:09:55 +01:00
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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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2001-05-04 05:57:05 +02:00
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return ret;
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}
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2015-07-02 15:15:34 +02:00
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#endif /* WITH_OPENSSL */
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