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/* $OpenBSD: verify.c,v 1.2 2005/05/28 08:07:45 marius Exp $ */
/*
* verify.c
*
* Copyright (c) 2001 Dug Song <dugsong@arbor.net>
* Copyright (c) 2001 Arbor Networks, Inc.
*
* 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.
* 3. The names of the copyright holders may not be used to endorse or
* promote products derived from this software without specific
* prior written permission.
*
* THIS SOFTWARE IS PROVIDED ``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.
*
* $Vendor: verify.c,v 1.3 2005/04/07 23:19:35 dugsong Exp $
*/
#include <sys/types.h>
#include <openssl/ssl.h>
#include <openssl/evp.h>
#include <openssl/sha.h>
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "extern.h"
#include "gzip.h"
#include "key.h"
#include "util.h"
static int
verify_signature(struct key *key, FILE *fin)
{
struct gzip_header gh;
struct gzip_xfield *gx;
struct gzsig_data *gd;
u_char *sig, digest[20], buf[8192], sbuf[4096];
SHA_CTX ctx;
int i, siglen;
/* Read gzip header. */
if ((i = fread((u_char *)&gh, 1, sizeof(gh), fin)) != sizeof(gh)) {
fprintf(stderr, "Error reading gzip header: %s\n",
strerror(errno));
return (-1);
}
/* Verify gzip header. */
if (memcmp(gh.magic, GZIP_MAGIC, sizeof(gh.magic)) != 0) {
fprintf(stderr, "Invalid gzip file\n");
return (-1);
} else if (gh.flags & GZIP_FCONT){
fprintf(stderr, "Multi-part gzip files not supported\n");
return (-1);
} else if ((gh.flags & GZIP_FEXTRA) == 0) {
fprintf(stderr, "No gzip signature found\n");
return (-1);
}
/* Read signature. */
gx = (struct gzip_xfield *)buf;
if ((i = fread((u_char *)gx, 1, sizeof(*gx), fin)) != sizeof(*gx)) {
fprintf(stderr, "Error reading extra field: %s\n",
strerror(errno));
return (-1);
}
if (memcmp(gx->subfield.id, GZSIG_ID, sizeof(gx->subfield.id)) != 0) {
fprintf(stderr, "Unknown extra field\n");
return (-1);
}
gx->subfield.len = letoh16(gx->subfield.len);
if (gx->subfield.len <= 0 || gx->subfield.len > sizeof(sbuf)) {
fprintf(stderr, "Invalid signature length\n");
return (-1);
}
gd = (struct gzsig_data *)sbuf;
if ((i = fread((u_char *)gd, 1, gx->subfield.len, fin)) !=
gx->subfield.len) {
fprintf(stderr, "Error reading signature: %s\n",
strerror(errno));
return (-1);
}
/* Skip over any options. */
if (gh.flags & GZIP_FNAME) {
while (getc(fin) != '\0')
;
}
if (gh.flags & GZIP_FCOMMENT) {
while (getc(fin) != '\0')
;
}
if (gh.flags & GZIP_FENCRYPT &&
fread(buf, 1, GZIP_FENCRYPT_LEN, fin) != GZIP_FENCRYPT_LEN)
return (-1);
/* Check signature version. */
if (gd->version != GZSIG_VERSION) {
fprintf(stderr, "Unknown signature version: %d\n",
gd->version);
return (-1);
}
/* Compute SHA1 checksum over compressed data and trailer. */
sig = (u_char *)(gd + 1);
siglen = gx->subfield.len - sizeof(*gd);
SHA1_Init(&ctx);
while ((i = fread(buf, 1, sizeof(buf), fin)) > 0) {
SHA1_Update(&ctx, buf, i);
}
SHA1_Final(digest, &ctx);
/* Verify signature. */
if (key_verify(key, digest, sizeof(digest), sig, siglen) < 0) {
fprintf(stderr, "Error verifying signature\n");
return (-1);
}
return (0);
}
void
verify_usage(void)
{
fprintf(stderr, "Usage: gzsig verify [-v] pubkey [file ...]\n");
}
void
verify(int argc, char *argv[])
{
struct key *key;
char *gzipfile;
FILE *fin;
int i, error, vflag;
vflag = 0;
while ((i = getopt(argc, argv, "vh?")) != -1) {
switch (i) {
case 'v':
vflag = 1;
break;
default:
verify_usage();
exit(1);
}
}
argc -= optind;
argv += optind;
if (argc < 1) {
verify_usage();
exit(1);
}
OpenSSL_add_all_algorithms();
if ((key = key_new()) == NULL)
fatal(1, "Can't initialize public key");
if (key_load_public(key, argv[0]) < 0)
fatal(1, "Can't load public key");
if (argc == 1 || *argv[1] == '-') {
argc = 0;
if (verify_signature(key, stdin) == 0) {
if (vflag)
fprintf(stderr, "Verified input\n");
} else
fatal(1, "Couldn't verify input");
}
for (i = 1; i < argc; i++) {
gzipfile = argv[i];
if ((fin = fopen(gzipfile, "r")) < 0) {
fprintf(stderr, "Couldn't open %s: %s\n",
gzipfile, strerror(errno));
continue;
}
error = verify_signature(key, fin);
fclose(fin);
if (!error) {
if (vflag)
fprintf(stderr, "Verified %s\n", gzipfile);
} else
fatal(1, "Couldn't verify %s", gzipfile);
}
key_free(key);
}
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