diff options
Diffstat (limited to 'crypto/openssh/ssh-dss.c')
| -rw-r--r-- | crypto/openssh/ssh-dss.c | 187 |
1 files changed, 187 insertions, 0 deletions
diff --git a/crypto/openssh/ssh-dss.c b/crypto/openssh/ssh-dss.c new file mode 100644 index 0000000..ede5e21 --- /dev/null +++ b/crypto/openssh/ssh-dss.c @@ -0,0 +1,187 @@ +/* $OpenBSD: ssh-dss.c,v 1.27 2010/08/31 09:58:37 djm 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" + +#include <sys/types.h> + +#include <openssl/bn.h> +#include <openssl/evp.h> + +#include <stdarg.h> +#include <string.h> + +#include "xmalloc.h" +#include "buffer.h" +#include "compat.h" +#include "log.h" +#include "key.h" + +#define INTBLOB_LEN 20 +#define SIGBLOB_LEN (2*INTBLOB_LEN) + +int +ssh_dss_sign(const Key *key, u_char **sigp, u_int *lenp, + const u_char *data, u_int datalen) +{ + DSA_SIG *sig; + const EVP_MD *evp_md = EVP_sha1(); + EVP_MD_CTX md; + u_char digest[EVP_MAX_MD_SIZE], sigblob[SIGBLOB_LEN]; + u_int rlen, slen, len, dlen; + Buffer b; + + if (key == NULL || key->dsa == NULL || (key->type != KEY_DSA && + key->type != KEY_DSA_CERT && key->type != KEY_DSA_CERT_V00)) { + error("ssh_dss_sign: no DSA key"); + return -1; + } + EVP_DigestInit(&md, evp_md); + EVP_DigestUpdate(&md, data, datalen); + EVP_DigestFinal(&md, digest, &dlen); + + sig = DSA_do_sign(digest, dlen, key->dsa); + memset(digest, 'd', sizeof(digest)); + + if (sig == NULL) { + error("ssh_dss_sign: sign failed"); + return -1; + } + + rlen = BN_num_bytes(sig->r); + slen = BN_num_bytes(sig->s); + if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { + error("bad sig size %u %u", rlen, slen); + DSA_SIG_free(sig); + return -1; + } + memset(sigblob, 0, SIGBLOB_LEN); + BN_bn2bin(sig->r, sigblob+ SIGBLOB_LEN - INTBLOB_LEN - rlen); + BN_bn2bin(sig->s, sigblob+ SIGBLOB_LEN - slen); + DSA_SIG_free(sig); + + if (datafellows & SSH_BUG_SIGBLOB) { + if (lenp != NULL) + *lenp = SIGBLOB_LEN; + if (sigp != NULL) { + *sigp = xmalloc(SIGBLOB_LEN); + memcpy(*sigp, sigblob, SIGBLOB_LEN); + } + } else { + /* ietf-drafts */ + buffer_init(&b); + buffer_put_cstring(&b, "ssh-dss"); + buffer_put_string(&b, sigblob, SIGBLOB_LEN); + len = buffer_len(&b); + if (lenp != NULL) + *lenp = len; + if (sigp != NULL) { + *sigp = xmalloc(len); + memcpy(*sigp, buffer_ptr(&b), len); + } + buffer_free(&b); + } + return 0; +} +int +ssh_dss_verify(const Key *key, const u_char *signature, u_int signaturelen, + const u_char *data, u_int datalen) +{ + DSA_SIG *sig; + const EVP_MD *evp_md = EVP_sha1(); + EVP_MD_CTX md; + u_char digest[EVP_MAX_MD_SIZE], *sigblob; + u_int len, dlen; + int rlen, ret; + Buffer b; + + if (key == NULL || key->dsa == NULL || (key->type != KEY_DSA && + key->type != KEY_DSA_CERT && key->type != KEY_DSA_CERT_V00)) { + error("ssh_dss_verify: no DSA key"); + return -1; + } + + /* fetch signature */ + if (datafellows & SSH_BUG_SIGBLOB) { + sigblob = xmalloc(signaturelen); + memcpy(sigblob, signature, signaturelen); + len = signaturelen; + } else { + /* ietf-drafts */ + char *ktype; + buffer_init(&b); + buffer_append(&b, signature, signaturelen); + ktype = buffer_get_cstring(&b, NULL); + if (strcmp("ssh-dss", ktype) != 0) { + error("ssh_dss_verify: cannot handle type %s", ktype); + buffer_free(&b); + xfree(ktype); + return -1; + } + xfree(ktype); + sigblob = buffer_get_string(&b, &len); + rlen = buffer_len(&b); + buffer_free(&b); + if (rlen != 0) { + error("ssh_dss_verify: " + "remaining bytes in signature %d", rlen); + xfree(sigblob); + return -1; + } + } + + if (len != SIGBLOB_LEN) { + fatal("bad sigbloblen %u != SIGBLOB_LEN", len); + } + + /* parse signature */ + if ((sig = DSA_SIG_new()) == NULL) + fatal("ssh_dss_verify: DSA_SIG_new failed"); + if ((sig->r = BN_new()) == NULL) + fatal("ssh_dss_verify: BN_new failed"); + if ((sig->s = BN_new()) == NULL) + fatal("ssh_dss_verify: BN_new failed"); + if ((BN_bin2bn(sigblob, INTBLOB_LEN, sig->r) == NULL) || + (BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s) == NULL)) + fatal("ssh_dss_verify: BN_bin2bn failed"); + + /* clean up */ + memset(sigblob, 0, len); + xfree(sigblob); + + /* sha1 the data */ + EVP_DigestInit(&md, evp_md); + EVP_DigestUpdate(&md, data, datalen); + EVP_DigestFinal(&md, digest, &dlen); + + ret = DSA_do_verify(digest, dlen, sig, key->dsa); + memset(digest, 'd', sizeof(digest)); + + DSA_SIG_free(sig); + + debug("ssh_dss_verify: signature %s", + ret == 1 ? "correct" : ret == 0 ? "incorrect" : "error"); + return ret; +} |
