2015-01-05 16:09:55 +00:00
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/* $OpenBSD: ssh-rsa.c,v 1.52 2014/06/24 01:13:21 djm Exp $ */
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2001-05-04 03:57:05 +00:00
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/*
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2004-01-07 11:10:17 +00:00
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* Copyright (c) 2000, 2003 Markus Friedl <markus@openbsd.org>
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2001-05-04 03:57:05 +00:00
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*
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2004-01-07 11:10:17 +00:00
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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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2001-05-04 03:57:05 +00:00
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*
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2004-01-07 11:10:17 +00:00
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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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2001-05-04 03:57:05 +00:00
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*/
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2006-09-30 13:29:51 +00:00
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2001-05-04 03:57:05 +00:00
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#include "includes.h"
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2006-09-30 13:29:51 +00:00
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#include <sys/types.h>
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2001-05-04 03:57:05 +00:00
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#include <openssl/evp.h>
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#include <openssl/err.h>
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2006-09-30 13:29:51 +00:00
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#include <stdarg.h>
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#include <string.h>
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2015-01-05 16:09:55 +00:00
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#include "sshbuf.h"
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2001-05-04 03:57:05 +00:00
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#include "compat.h"
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2015-01-05 16:09:55 +00:00
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#include "ssherr.h"
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#define SSHKEY_INTERNAL
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#include "sshkey.h"
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2014-01-30 10:56:49 +00:00
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#include "digest.h"
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2001-05-04 03:57:05 +00:00
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2015-01-05 16:09:55 +00:00
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static int openssh_RSA_verify(int, u_char *, size_t, u_char *, size_t, RSA *);
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2002-10-29 09:43:00 +00:00
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2001-05-04 03:57:05 +00:00
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/* RSASSA-PKCS1-v1_5 (PKCS #1 v2.0 signature) with SHA1 */
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int
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2015-01-05 16:09:55 +00:00
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ssh_rsa_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 03:57:05 +00:00
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{
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2014-01-30 10:56:49 +00:00
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int hash_alg;
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2015-01-05 16:09:55 +00:00
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u_char digest[SSH_DIGEST_MAX_LENGTH], *sig = NULL;
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size_t slen;
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u_int dlen, len;
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int nid, ret = SSH_ERR_INTERNAL_ERROR;
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struct sshbuf *b = NULL;
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2001-05-04 03:57:05 +00:00
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2015-01-05 16:09:55 +00:00
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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->rsa == NULL ||
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sshkey_type_plain(key->type) != KEY_RSA)
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return SSH_ERR_INVALID_ARGUMENT;
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slen = RSA_size(key->rsa);
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if (slen <= 0 || slen > SSHBUF_MAX_BIGNUM)
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return SSH_ERR_INVALID_ARGUMENT;
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2014-01-30 10:56:49 +00:00
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/* hash the data */
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hash_alg = SSH_DIGEST_SHA1;
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nid = NID_sha1;
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2015-01-05 16:09:55 +00:00
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if ((dlen = ssh_digest_bytes(hash_alg)) == 0)
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return SSH_ERR_INTERNAL_ERROR;
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if ((ret = ssh_digest_memory(hash_alg, data, datalen,
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digest, sizeof(digest))) != 0)
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goto out;
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2001-05-04 03:57:05 +00:00
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2015-01-05 16:09:55 +00:00
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if ((sig = malloc(slen)) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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2006-09-30 13:29:51 +00:00
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2015-01-05 16:09:55 +00:00
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if (RSA_sign(nid, digest, dlen, sig, &len, key->rsa) != 1) {
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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goto out;
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2001-05-04 03:57:05 +00:00
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}
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if (len < slen) {
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2015-01-05 16:09:55 +00:00
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size_t diff = slen - len;
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2001-05-04 03:57:05 +00:00
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memmove(sig + diff, sig, len);
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2014-03-22 15:23:38 +00:00
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explicit_bzero(sig, diff);
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2001-05-04 03:57:05 +00:00
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} else if (len > slen) {
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2015-01-05 16:09:55 +00:00
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ret = SSH_ERR_INTERNAL_ERROR;
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goto out;
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2001-05-04 03:57:05 +00:00
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}
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/* encode signature */
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2015-01-05 16:09:55 +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-rsa")) != 0 ||
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(ret = sshbuf_put_string(b, sig, slen)) != 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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2002-10-29 09:43:00 +00:00
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if (lenp != NULL)
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*lenp = len;
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2015-01-05 16:09:55 +00:00
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ret = 0;
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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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explicit_bzero(sig, slen);
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free(sig);
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2002-10-29 09:43:00 +00:00
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}
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2015-01-05 16:09:55 +00:00
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if (b != NULL)
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sshbuf_free(b);
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2001-05-04 03:57:05 +00:00
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return 0;
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}
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int
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2015-01-05 16:09:55 +00:00
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ssh_rsa_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 03:57:05 +00:00
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{
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2015-01-05 16:09:55 +00:00
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char *ktype = NULL;
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int hash_alg, ret = SSH_ERR_INTERNAL_ERROR;
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size_t len, diff, modlen, dlen;
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struct sshbuf *b = NULL;
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u_char digest[SSH_DIGEST_MAX_LENGTH], *osigblob, *sigblob = NULL;
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2001-05-04 03:57:05 +00:00
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2015-01-05 16:09:55 +00:00
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if (key == NULL || key->rsa == NULL ||
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sshkey_type_plain(key->type) != KEY_RSA ||
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BN_num_bits(key->rsa->n) < SSH_RSA_MINIMUM_MODULUS_SIZE)
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return SSH_ERR_INVALID_ARGUMENT;
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2014-01-30 10:56:49 +00:00
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2015-01-05 16:09:55 +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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ret = SSH_ERR_INVALID_FORMAT;
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goto out;
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2001-05-04 03:57:05 +00:00
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}
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if (strcmp("ssh-rsa", ktype) != 0) {
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2015-01-05 16:09:55 +00:00
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ret = SSH_ERR_KEY_TYPE_MISMATCH;
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goto out;
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2001-05-04 03:57:05 +00:00
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}
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2015-01-05 16:09:55 +00:00
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if (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 (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 03:57:05 +00:00
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}
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2002-06-23 14:01:54 +00:00
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/* RSA_verify expects a signature of RSA_size */
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modlen = RSA_size(key->rsa);
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if (len > modlen) {
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2015-01-05 16:09:55 +00:00
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ret = SSH_ERR_KEY_BITS_MISMATCH;
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goto out;
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2002-06-23 14:01:54 +00:00
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} else if (len < modlen) {
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2015-01-05 16:09:55 +00:00
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diff = modlen - len;
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osigblob = sigblob;
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if ((sigblob = realloc(sigblob, modlen)) == NULL) {
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sigblob = osigblob; /* put it back for clear/free */
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ret = SSH_ERR_ALLOC_FAIL;
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goto out;
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}
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2002-06-23 14:01:54 +00:00
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memmove(sigblob + diff, sigblob, len);
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2014-03-22 15:23:38 +00:00
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explicit_bzero(sigblob, diff);
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2002-06-23 14:01:54 +00:00
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len = modlen;
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}
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2014-01-30 10:56:49 +00:00
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hash_alg = SSH_DIGEST_SHA1;
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if ((dlen = ssh_digest_bytes(hash_alg)) == 0) {
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2015-01-05 16:09:55 +00:00
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ret = SSH_ERR_INTERNAL_ERROR;
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goto out;
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2001-05-04 03:57:05 +00:00
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}
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2015-01-05 16:09:55 +00:00
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if ((ret = ssh_digest_memory(hash_alg, data, datalen,
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digest, sizeof(digest))) != 0)
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goto out;
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2001-05-04 03:57:05 +00:00
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2014-01-30 10:56:49 +00:00
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ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
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key->rsa);
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2015-01-05 16:09:55 +00:00
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out:
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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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if (ktype != NULL)
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free(ktype);
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if (b != NULL)
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sshbuf_free(b);
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2014-03-22 15:23:38 +00:00
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explicit_bzero(digest, sizeof(digest));
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2001-05-04 03:57:05 +00:00
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return ret;
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}
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2002-10-29 09:43:00 +00:00
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/*
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* See:
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* http://www.rsasecurity.com/rsalabs/pkcs/pkcs-1/
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* ftp://ftp.rsasecurity.com/pub/pkcs/pkcs-1/pkcs-1v2-1.asn
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*/
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/*
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* id-sha1 OBJECT IDENTIFIER ::= { iso(1) identified-organization(3)
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* oiw(14) secsig(3) algorithms(2) 26 }
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*/
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static const u_char id_sha1[] = {
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0x30, 0x21, /* type Sequence, length 0x21 (33) */
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0x30, 0x09, /* type Sequence, length 0x09 */
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0x06, 0x05, /* type OID, length 0x05 */
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0x2b, 0x0e, 0x03, 0x02, 0x1a, /* id-sha1 OID */
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0x05, 0x00, /* NULL */
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0x04, 0x14 /* Octet string, length 0x14 (20), followed by sha1 hash */
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};
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static int
|
2015-01-05 16:09:55 +00:00
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openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
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u_char *sigbuf, size_t siglen, RSA *rsa)
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2002-10-29 09:43:00 +00:00
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{
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2015-01-05 16:09:55 +00:00
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size_t ret, rsasize = 0, oidlen = 0, hlen = 0;
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2010-11-08 10:45:44 +00:00
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int len, oidmatch, hashmatch;
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2002-10-29 09:43:00 +00:00
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const u_char *oid = NULL;
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u_char *decrypted = NULL;
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2015-01-05 16:09:55 +00:00
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ret = SSH_ERR_INTERNAL_ERROR;
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2014-01-30 10:56:49 +00:00
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switch (hash_alg) {
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case SSH_DIGEST_SHA1:
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2002-10-29 09:43:00 +00:00
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oid = id_sha1;
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oidlen = sizeof(id_sha1);
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hlen = 20;
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break;
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default:
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goto done;
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}
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if (hashlen != hlen) {
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2015-01-05 16:09:55 +00:00
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ret = SSH_ERR_INVALID_ARGUMENT;
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2002-10-29 09:43:00 +00:00
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goto done;
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}
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rsasize = RSA_size(rsa);
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2015-01-05 16:09:55 +00:00
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if (rsasize <= 0 || rsasize > SSHBUF_MAX_BIGNUM ||
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siglen == 0 || siglen > rsasize) {
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ret = SSH_ERR_INVALID_ARGUMENT;
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goto done;
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}
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if ((decrypted = malloc(rsasize)) == NULL) {
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ret = SSH_ERR_ALLOC_FAIL;
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2002-10-29 09:43:00 +00:00
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goto done;
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}
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if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
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RSA_PKCS1_PADDING)) < 0) {
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2015-01-05 16:09:55 +00:00
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ret = SSH_ERR_LIBCRYPTO_ERROR;
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2002-10-29 09:43:00 +00:00
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goto done;
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}
|
2015-01-05 16:09:55 +00:00
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if (len < 0 || (size_t)len != hlen + oidlen) {
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ret = SSH_ERR_INVALID_FORMAT;
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2002-10-29 09:43:00 +00:00
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goto done;
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}
|
2010-11-08 10:45:44 +00:00
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oidmatch = timingsafe_bcmp(decrypted, oid, oidlen) == 0;
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hashmatch = timingsafe_bcmp(decrypted + oidlen, hash, hlen) == 0;
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2015-01-05 16:09:55 +00:00
|
|
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if (!oidmatch || !hashmatch) {
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ret = SSH_ERR_SIGNATURE_INVALID;
|
2002-10-29 09:43:00 +00:00
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goto done;
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|
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}
|
2015-01-05 16:09:55 +00:00
|
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ret = 0;
|
2002-10-29 09:43:00 +00:00
|
|
|
done:
|
2015-01-05 16:09:55 +00:00
|
|
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if (decrypted) {
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|
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explicit_bzero(decrypted, rsasize);
|
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|
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free(decrypted);
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|
|
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}
|
2002-10-29 09:43:00 +00:00
|
|
|
return ret;
|
|
|
|
}
|