| /* $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" |
| |
| #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 */ |