summaryrefslogtreecommitdiffstats
path: root/ssh-dss.c
diff options
context:
space:
mode:
Diffstat (limited to 'ssh-dss.c')
-rw-r--r--ssh-dss.c209
1 files changed, 209 insertions, 0 deletions
diff --git a/ssh-dss.c b/ssh-dss.c
new file mode 100644
index 0000000..a23c383
--- /dev/null
+++ b/ssh-dss.c
@@ -0,0 +1,209 @@
+/* $OpenBSD: ssh-dss.c,v 1.37 2018/02/07 02:06:51 jsing Exp $ */
+/*
+ * Copyright (c) 2000 Markus Friedl. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "includes.h"
+
+#ifdef WITH_OPENSSL
+
+#include <sys/types.h>
+
+#include <openssl/bn.h>
+#include <openssl/dsa.h>
+#include <openssl/evp.h>
+
+#include <stdarg.h>
+#include <string.h>
+
+#include "sshbuf.h"
+#include "compat.h"
+#include "ssherr.h"
+#include "digest.h"
+#define SSHKEY_INTERNAL
+#include "sshkey.h"
+
+#include "openbsd-compat/openssl-compat.h"
+
+#define INTBLOB_LEN 20
+#define SIGBLOB_LEN (2*INTBLOB_LEN)
+
+int
+ssh_dss_sign(const struct sshkey *key, u_char **sigp, size_t *lenp,
+ const u_char *data, size_t datalen, u_int compat)
+{
+ DSA_SIG *sig = NULL;
+ const BIGNUM *sig_r, *sig_s;
+ u_char digest[SSH_DIGEST_MAX_LENGTH], sigblob[SIGBLOB_LEN];
+ size_t rlen, slen, len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
+ struct sshbuf *b = NULL;
+ int ret = SSH_ERR_INVALID_ARGUMENT;
+
+ if (lenp != NULL)
+ *lenp = 0;
+ if (sigp != NULL)
+ *sigp = NULL;
+
+ if (key == NULL || key->dsa == NULL ||
+ sshkey_type_plain(key->type) != KEY_DSA)
+ return SSH_ERR_INVALID_ARGUMENT;
+ if (dlen == 0)
+ return SSH_ERR_INTERNAL_ERROR;
+
+ if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
+ digest, sizeof(digest))) != 0)
+ goto out;
+
+ if ((sig = DSA_do_sign(digest, dlen, key->dsa)) == NULL) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+
+ DSA_SIG_get0(sig, &sig_r, &sig_s);
+ rlen = BN_num_bytes(sig_r);
+ slen = BN_num_bytes(sig_s);
+ if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) {
+ ret = SSH_ERR_INTERNAL_ERROR;
+ goto out;
+ }
+ explicit_bzero(sigblob, SIGBLOB_LEN);
+ BN_bn2bin(sig_r, sigblob + SIGBLOB_LEN - INTBLOB_LEN - rlen);
+ BN_bn2bin(sig_s, sigblob + SIGBLOB_LEN - slen);
+
+ if ((b = sshbuf_new()) == NULL) {
+ ret = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((ret = sshbuf_put_cstring(b, "ssh-dss")) != 0 ||
+ (ret = sshbuf_put_string(b, sigblob, SIGBLOB_LEN)) != 0)
+ goto out;
+
+ len = sshbuf_len(b);
+ if (sigp != NULL) {
+ if ((*sigp = malloc(len)) == NULL) {
+ ret = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ memcpy(*sigp, sshbuf_ptr(b), len);
+ }
+ if (lenp != NULL)
+ *lenp = len;
+ ret = 0;
+ out:
+ explicit_bzero(digest, sizeof(digest));
+ DSA_SIG_free(sig);
+ sshbuf_free(b);
+ return ret;
+}
+
+int
+ssh_dss_verify(const struct sshkey *key,
+ const u_char *signature, size_t signaturelen,
+ const u_char *data, size_t datalen, u_int compat)
+{
+ DSA_SIG *sig = NULL;
+ BIGNUM *sig_r = NULL, *sig_s = NULL;
+ u_char digest[SSH_DIGEST_MAX_LENGTH], *sigblob = NULL;
+ size_t len, dlen = ssh_digest_bytes(SSH_DIGEST_SHA1);
+ int ret = SSH_ERR_INTERNAL_ERROR;
+ struct sshbuf *b = NULL;
+ char *ktype = NULL;
+
+ if (key == NULL || key->dsa == NULL ||
+ sshkey_type_plain(key->type) != KEY_DSA ||
+ signature == NULL || signaturelen == 0)
+ return SSH_ERR_INVALID_ARGUMENT;
+ if (dlen == 0)
+ return SSH_ERR_INTERNAL_ERROR;
+
+ /* fetch signature */
+ if ((b = sshbuf_from(signature, signaturelen)) == NULL)
+ return SSH_ERR_ALLOC_FAIL;
+ if (sshbuf_get_cstring(b, &ktype, NULL) != 0 ||
+ sshbuf_get_string(b, &sigblob, &len) != 0) {
+ ret = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+ if (strcmp("ssh-dss", ktype) != 0) {
+ ret = SSH_ERR_KEY_TYPE_MISMATCH;
+ goto out;
+ }
+ if (sshbuf_len(b) != 0) {
+ ret = SSH_ERR_UNEXPECTED_TRAILING_DATA;
+ goto out;
+ }
+
+ if (len != SIGBLOB_LEN) {
+ ret = SSH_ERR_INVALID_FORMAT;
+ goto out;
+ }
+
+ /* parse signature */
+ if ((sig = DSA_SIG_new()) == NULL ||
+ (sig_r = BN_new()) == NULL ||
+ (sig_s = BN_new()) == NULL) {
+ ret = SSH_ERR_ALLOC_FAIL;
+ goto out;
+ }
+ if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig_r) == NULL) ||
+ (BN_bin2bn(sigblob + INTBLOB_LEN, INTBLOB_LEN, sig_s) == NULL)) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ if (!DSA_SIG_set0(sig, sig_r, sig_s)) {
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+ sig_r = sig_s = NULL; /* transferred */
+
+ /* sha1 the data */
+ if ((ret = ssh_digest_memory(SSH_DIGEST_SHA1, data, datalen,
+ digest, sizeof(digest))) != 0)
+ goto out;
+
+ switch (DSA_do_verify(digest, dlen, sig, key->dsa)) {
+ case 1:
+ ret = 0;
+ break;
+ case 0:
+ ret = SSH_ERR_SIGNATURE_INVALID;
+ goto out;
+ default:
+ ret = SSH_ERR_LIBCRYPTO_ERROR;
+ goto out;
+ }
+
+ out:
+ explicit_bzero(digest, sizeof(digest));
+ DSA_SIG_free(sig);
+ BN_clear_free(sig_r);
+ BN_clear_free(sig_s);
+ sshbuf_free(b);
+ free(ktype);
+ if (sigblob != NULL) {
+ explicit_bzero(sigblob, len);
+ free(sigblob);
+ }
+ return ret;
+}
+#endif /* WITH_OPENSSL */