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Diffstat (limited to '')
| -rw-r--r-- | ssh-dss.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/ssh-dss.c b/ssh-dss.c new file mode 100644 index 0000000..fddc29c --- /dev/null +++ b/ssh-dss.c @@ -0,0 +1,207 @@ +/* $OpenBSD: ssh-dss.c,v 1.39 2020/02/26 13:40:09 jsg 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) + freezero(sigblob, len); + return ret; +} +#endif /* WITH_OPENSSL */ |