diff options
Diffstat (limited to 'crypto/openssh/ssh-dss.c')
| -rw-r--r-- | crypto/openssh/ssh-dss.c | 217 |
1 files changed, 217 insertions, 0 deletions
diff --git a/crypto/openssh/ssh-dss.c b/crypto/openssh/ssh-dss.c new file mode 100644 index 0000000..adc8f98 --- /dev/null +++ b/crypto/openssh/ssh-dss.c @@ -0,0 +1,217 @@ +/* + * 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" +RCSID("$OpenBSD: ssh-dss.c,v 1.6 2001/02/08 19:30:52 itojun Exp $"); + +#include <openssl/bn.h> +#include <openssl/evp.h> + +#include "xmalloc.h" +#include "buffer.h" +#include "bufaux.h" +#include "compat.h" +#include "log.h" +#include "key.h" +#include "ssh-dss.h" + +#define INTBLOB_LEN 20 +#define SIGBLOB_LEN (2*INTBLOB_LEN) + +int +ssh_dss_sign( + Key *key, + u_char **sigp, int *lenp, + u_char *data, int datalen) +{ + u_char *digest; + u_char *ret; + DSA_SIG *sig; + EVP_MD *evp_md = EVP_sha1(); + EVP_MD_CTX md; + u_int rlen; + u_int slen; + u_int len, dlen; + u_char sigblob[SIGBLOB_LEN]; + Buffer b; + + if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { + error("ssh_dss_sign: no DSA key"); + return -1; + } + dlen = evp_md->md_size; + digest = xmalloc(dlen); + EVP_DigestInit(&md, evp_md); + EVP_DigestUpdate(&md, data, datalen); + EVP_DigestFinal(&md, digest, NULL); + + sig = DSA_do_sign(digest, dlen, key->dsa); + if (sig == NULL) { + fatal("ssh_dss_sign: cannot sign"); + } + memset(digest, 0, dlen); + xfree(digest); + + rlen = BN_num_bytes(sig->r); + slen = BN_num_bytes(sig->s); + if (rlen > INTBLOB_LEN || slen > INTBLOB_LEN) { + error("bad sig size %d %d", rlen, slen); + DSA_SIG_free(sig); + return -1; + } + debug("sig size %d %d", rlen, slen); + + 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) { + debug("datafellows"); + ret = xmalloc(SIGBLOB_LEN); + memcpy(ret, sigblob, SIGBLOB_LEN); + if (lenp != NULL) + *lenp = SIGBLOB_LEN; + if (sigp != NULL) + *sigp = ret; + } else { + /* ietf-drafts */ + buffer_init(&b); + buffer_put_cstring(&b, "ssh-dss"); + buffer_put_string(&b, sigblob, SIGBLOB_LEN); + len = buffer_len(&b); + ret = xmalloc(len); + memcpy(ret, buffer_ptr(&b), len); + buffer_free(&b); + if (lenp != NULL) + *lenp = len; + if (sigp != NULL) + *sigp = ret; + } + return 0; +} +int +ssh_dss_verify( + Key *key, + u_char *signature, int signaturelen, + u_char *data, int datalen) +{ + Buffer b; + u_char *digest; + DSA_SIG *sig; + EVP_MD *evp_md = EVP_sha1(); + EVP_MD_CTX md; + u_char *sigblob; + char *txt; + u_int len, dlen; + int rlen; + int ret; + + if (key == NULL || key->type != KEY_DSA || key->dsa == NULL) { + error("ssh_dss_verify: no DSA key"); + return -1; + } + + if (!(datafellows & SSH_BUG_SIGBLOB) && + signaturelen == SIGBLOB_LEN) { + datafellows |= ~SSH_BUG_SIGBLOB; + log("autodetect SSH_BUG_SIGBLOB"); + } else if ((datafellows & SSH_BUG_SIGBLOB) && + signaturelen != SIGBLOB_LEN) { + log("autoremove SSH_BUG_SIGBLOB"); + datafellows &= ~SSH_BUG_SIGBLOB; + } + + debug("len %d datafellows %d", signaturelen, datafellows); + + /* fetch signature */ + if (datafellows & SSH_BUG_SIGBLOB) { + sigblob = signature; + len = signaturelen; + } else { + /* ietf-drafts */ + char *ktype; + buffer_init(&b); + buffer_append(&b, (char *) signature, signaturelen); + ktype = buffer_get_string(&b, NULL); + if (strcmp("ssh-dss", ktype) != 0) { + error("ssh_dss_verify: cannot handle type %s", ktype); + buffer_free(&b); + return -1; + } + sigblob = (u_char *)buffer_get_string(&b, &len); + rlen = buffer_len(&b); + if(rlen != 0) { + error("remaining bytes in signature %d", rlen); + buffer_free(&b); + return -1; + } + buffer_free(&b); + xfree(ktype); + } + + if (len != SIGBLOB_LEN) { + fatal("bad sigbloblen %d != SIGBLOB_LEN", len); + } + + /* parse signature */ + sig = DSA_SIG_new(); + sig->r = BN_new(); + sig->s = BN_new(); + BN_bin2bn(sigblob, INTBLOB_LEN, sig->r); + BN_bin2bn(sigblob+ INTBLOB_LEN, INTBLOB_LEN, sig->s); + + if (!(datafellows & SSH_BUG_SIGBLOB)) { + memset(sigblob, 0, len); + xfree(sigblob); + } + + /* sha1 the data */ + dlen = evp_md->md_size; + digest = xmalloc(dlen); + EVP_DigestInit(&md, evp_md); + EVP_DigestUpdate(&md, data, datalen); + EVP_DigestFinal(&md, digest, NULL); + + ret = DSA_do_verify(digest, dlen, sig, key->dsa); + + memset(digest, 0, dlen); + xfree(digest); + DSA_SIG_free(sig); + + switch (ret) { + case 1: + txt = "correct"; + break; + case 0: + txt = "incorrect"; + break; + case -1: + default: + txt = "error"; + break; + } + debug("ssh_dss_verify: signature %s", txt); + return ret; +} |
