mirror of
git://anongit.mindrot.org/openssh.git
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4e838120a7
on ok markus@ OpenBSD-Commit-ID: 4f8e98fc1fd6de399d0921d5b31b3127a03f581d
458 lines
12 KiB
C
458 lines
12 KiB
C
/* $OpenBSD: ssh-dss.c,v 1.50 2024/01/11 01:45:36 djm Exp $ */
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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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#if defined(WITH_OPENSSL) && defined(WITH_DSA)
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#include <sys/types.h>
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#include <openssl/bn.h>
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#include <openssl/dsa.h>
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#include <openssl/evp.h>
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#include <stdarg.h>
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#include <string.h>
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#include "sshbuf.h"
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#include "ssherr.h"
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#include "digest.h"
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#define SSHKEY_INTERNAL
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#include "sshkey.h"
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#include "openbsd-compat/openssl-compat.h"
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#define INTBLOB_LEN 20
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#define SIGBLOB_LEN (2*INTBLOB_LEN)
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static u_int
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ssh_dss_size(const struct sshkey *key)
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{
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const BIGNUM *dsa_p;
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if (key->dsa == NULL)
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return 0;
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DSA_get0_pqg(key->dsa, &dsa_p, NULL, NULL);
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return BN_num_bits(dsa_p);
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}
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static int
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ssh_dss_alloc(struct sshkey *k)
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{
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if ((k->dsa = DSA_new()) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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return 0;
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}
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static void
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ssh_dss_cleanup(struct sshkey *k)
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{
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DSA_free(k->dsa);
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k->dsa = NULL;
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}
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static int
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ssh_dss_equal(const struct sshkey *a, const struct sshkey *b)
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{
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const BIGNUM *dsa_p_a, *dsa_q_a, *dsa_g_a, *dsa_pub_key_a;
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const BIGNUM *dsa_p_b, *dsa_q_b, *dsa_g_b, *dsa_pub_key_b;
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if (a->dsa == NULL || b->dsa == NULL)
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return 0;
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DSA_get0_pqg(a->dsa, &dsa_p_a, &dsa_q_a, &dsa_g_a);
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DSA_get0_pqg(b->dsa, &dsa_p_b, &dsa_q_b, &dsa_g_b);
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DSA_get0_key(a->dsa, &dsa_pub_key_a, NULL);
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DSA_get0_key(b->dsa, &dsa_pub_key_b, NULL);
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if (dsa_p_a == NULL || dsa_p_b == NULL ||
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dsa_q_a == NULL || dsa_q_b == NULL ||
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dsa_g_a == NULL || dsa_g_b == NULL ||
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dsa_pub_key_a == NULL || dsa_pub_key_b == NULL)
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return 0;
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if (BN_cmp(dsa_p_a, dsa_p_b) != 0)
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return 0;
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if (BN_cmp(dsa_q_a, dsa_q_b) != 0)
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return 0;
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if (BN_cmp(dsa_g_a, dsa_g_b) != 0)
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return 0;
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if (BN_cmp(dsa_pub_key_a, dsa_pub_key_b) != 0)
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return 0;
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return 1;
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}
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static int
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ssh_dss_serialize_public(const struct sshkey *key, struct sshbuf *b,
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enum sshkey_serialize_rep opts)
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{
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int r;
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const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
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if (key->dsa == NULL)
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return SSH_ERR_INVALID_ARGUMENT;
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DSA_get0_pqg(key->dsa, &dsa_p, &dsa_q, &dsa_g);
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DSA_get0_key(key->dsa, &dsa_pub_key, NULL);
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if (dsa_p == NULL || dsa_q == NULL ||
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dsa_g == NULL || dsa_pub_key == NULL)
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return SSH_ERR_INTERNAL_ERROR;
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if ((r = sshbuf_put_bignum2(b, dsa_p)) != 0 ||
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(r = sshbuf_put_bignum2(b, dsa_q)) != 0 ||
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(r = sshbuf_put_bignum2(b, dsa_g)) != 0 ||
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(r = sshbuf_put_bignum2(b, dsa_pub_key)) != 0)
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return r;
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return 0;
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}
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static int
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ssh_dss_serialize_private(const struct sshkey *key, struct sshbuf *b,
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enum sshkey_serialize_rep opts)
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{
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int r;
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const BIGNUM *dsa_priv_key;
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DSA_get0_key(key->dsa, NULL, &dsa_priv_key);
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if (!sshkey_is_cert(key)) {
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if ((r = ssh_dss_serialize_public(key, b, opts)) != 0)
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return r;
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}
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if ((r = sshbuf_put_bignum2(b, dsa_priv_key)) != 0)
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return r;
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return 0;
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}
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static int
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ssh_dss_generate(struct sshkey *k, int bits)
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{
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DSA *private;
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if (bits != 1024)
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return SSH_ERR_KEY_LENGTH;
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if ((private = DSA_new()) == NULL)
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return SSH_ERR_ALLOC_FAIL;
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if (!DSA_generate_parameters_ex(private, bits, NULL, 0, NULL,
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NULL, NULL) || !DSA_generate_key(private)) {
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DSA_free(private);
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return SSH_ERR_LIBCRYPTO_ERROR;
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}
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k->dsa = private;
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return 0;
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}
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static int
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ssh_dss_copy_public(const struct sshkey *from, struct sshkey *to)
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{
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const BIGNUM *dsa_p, *dsa_q, *dsa_g, *dsa_pub_key;
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BIGNUM *dsa_p_dup = NULL, *dsa_q_dup = NULL, *dsa_g_dup = NULL;
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BIGNUM *dsa_pub_key_dup = NULL;
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int r = SSH_ERR_INTERNAL_ERROR;
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DSA_get0_pqg(from->dsa, &dsa_p, &dsa_q, &dsa_g);
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DSA_get0_key(from->dsa, &dsa_pub_key, NULL);
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if ((dsa_p_dup = BN_dup(dsa_p)) == NULL ||
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(dsa_q_dup = BN_dup(dsa_q)) == NULL ||
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(dsa_g_dup = BN_dup(dsa_g)) == NULL ||
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(dsa_pub_key_dup = BN_dup(dsa_pub_key)) == NULL) {
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r = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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if (!DSA_set0_pqg(to->dsa, dsa_p_dup, dsa_q_dup, dsa_g_dup)) {
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r = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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dsa_p_dup = dsa_q_dup = dsa_g_dup = NULL; /* transferred */
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if (!DSA_set0_key(to->dsa, dsa_pub_key_dup, NULL)) {
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r = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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dsa_pub_key_dup = NULL; /* transferred */
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/* success */
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r = 0;
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out:
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BN_clear_free(dsa_p_dup);
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BN_clear_free(dsa_q_dup);
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BN_clear_free(dsa_g_dup);
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BN_clear_free(dsa_pub_key_dup);
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return r;
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}
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static int
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ssh_dss_deserialize_public(const char *ktype, struct sshbuf *b,
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struct sshkey *key)
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{
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int ret = SSH_ERR_INTERNAL_ERROR;
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BIGNUM *dsa_p = NULL, *dsa_q = NULL, *dsa_g = NULL, *dsa_pub_key = NULL;
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if (sshbuf_get_bignum2(b, &dsa_p) != 0 ||
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sshbuf_get_bignum2(b, &dsa_q) != 0 ||
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sshbuf_get_bignum2(b, &dsa_g) != 0 ||
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sshbuf_get_bignum2(b, &dsa_pub_key) != 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 (!DSA_set0_pqg(key->dsa, dsa_p, dsa_q, dsa_g)) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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dsa_p = dsa_q = dsa_g = NULL; /* transferred */
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if (!DSA_set0_key(key->dsa, dsa_pub_key, NULL)) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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dsa_pub_key = NULL; /* transferred */
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#ifdef DEBUG_PK
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DSA_print_fp(stderr, key->dsa, 8);
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#endif
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/* success */
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ret = 0;
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out:
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BN_clear_free(dsa_p);
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BN_clear_free(dsa_q);
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BN_clear_free(dsa_g);
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BN_clear_free(dsa_pub_key);
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return ret;
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}
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static int
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ssh_dss_deserialize_private(const char *ktype, struct sshbuf *b,
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struct sshkey *key)
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{
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int r;
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BIGNUM *dsa_priv_key = NULL;
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if (!sshkey_is_cert(key)) {
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if ((r = ssh_dss_deserialize_public(ktype, b, key)) != 0)
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return r;
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}
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if ((r = sshbuf_get_bignum2(b, &dsa_priv_key)) != 0)
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return r;
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if (!DSA_set0_key(key->dsa, NULL, dsa_priv_key)) {
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BN_clear_free(dsa_priv_key);
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return SSH_ERR_LIBCRYPTO_ERROR;
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}
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return 0;
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}
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static int
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ssh_dss_sign(struct sshkey *key,
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u_char **sigp, size_t *lenp,
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const u_char *data, size_t datalen,
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const char *alg, const char *sk_provider, const char *sk_pin, u_int compat)
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{
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DSA_SIG *sig = NULL;
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const BIGNUM *sig_r, *sig_s;
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u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
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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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}
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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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if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
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ret = SSH_ERR_INTERNAL_ERROR;
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goto out;
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}
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explicit_bzero(sigblob, SIGBLOB_LEN);
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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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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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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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}
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if (lenp != NULL)
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*lenp = len;
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ret = 0;
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out:
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explicit_bzero(digest, sizeof(digest));
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DSA_SIG_free(sig);
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sshbuf_free(b);
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return ret;
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}
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static int
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ssh_dss_verify(const struct sshkey *key,
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const u_char *sig, size_t siglen,
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const u_char *data, size_t dlen, const char *alg, u_int compat,
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struct sshkey_sig_details **detailsp)
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{
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DSA_SIG *dsig = NULL;
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BIGNUM *sig_r = NULL, *sig_s = NULL;
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u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
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size_t len, hlen = 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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sshkey_type_plain(key->type) != KEY_DSA ||
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sig == NULL || siglen == 0)
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return SSH_ERR_INVALID_ARGUMENT;
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if (hlen == 0)
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return SSH_ERR_INTERNAL_ERROR;
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/* fetch signature */
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if ((b = sshbuf_from(sig, siglen)) == 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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}
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if (len != SIGBLOB_LEN) {
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ret = SSH_ERR_INVALID_FORMAT;
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goto out;
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}
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/* parse signature */
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if ((dsig = 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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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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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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}
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if (!DSA_SIG_set0(dsig, 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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/* sha1 the data */
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if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, dlen,
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digest, sizeof(digest))) != 0)
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goto out;
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switch (DSA_do_verify(digest, hlen, dsig, 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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}
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out:
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explicit_bzero(digest, sizeof(digest));
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DSA_SIG_free(dsig);
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BN_clear_free(sig_r);
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BN_clear_free(sig_s);
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sshbuf_free(b);
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free(ktype);
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if (sigblob != NULL)
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freezero(sigblob, len);
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return ret;
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}
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static const struct sshkey_impl_funcs sshkey_dss_funcs = {
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/* .size = */ ssh_dss_size,
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/* .alloc = */ ssh_dss_alloc,
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/* .cleanup = */ ssh_dss_cleanup,
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/* .equal = */ ssh_dss_equal,
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/* .ssh_serialize_public = */ ssh_dss_serialize_public,
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/* .ssh_deserialize_public = */ ssh_dss_deserialize_public,
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/* .ssh_serialize_private = */ ssh_dss_serialize_private,
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/* .ssh_deserialize_private = */ ssh_dss_deserialize_private,
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/* .generate = */ ssh_dss_generate,
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/* .copy_public = */ ssh_dss_copy_public,
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/* .sign = */ ssh_dss_sign,
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/* .verify = */ ssh_dss_verify,
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};
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const struct sshkey_impl sshkey_dss_impl = {
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/* .name = */ "ssh-dss",
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/* .shortname = */ "DSA",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_DSA,
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/* .nid = */ 0,
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/* .cert = */ 0,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_dss_funcs,
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};
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const struct sshkey_impl sshkey_dsa_cert_impl = {
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/* .name = */ "ssh-dss-cert-v01@openssh.com",
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/* .shortname = */ "DSA-CERT",
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/* .sigalg = */ NULL,
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/* .type = */ KEY_DSA_CERT,
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/* .nid = */ 0,
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/* .cert = */ 1,
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/* .sigonly = */ 0,
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/* .keybits = */ 0,
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/* .funcs = */ &sshkey_dss_funcs,
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};
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#endif /* WITH_OPENSSL && WITH_DSA */
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