File: [local] / src / usr.bin / signify / signify.c (download)
Revision 1.19, Thu Jan 9 19:05:21 2014 UTC (10 years, 5 months ago) by tedu
Branch: MAIN
Changes since 1.18: +3 -3 lines
change O_EXCL to O_TRUNC before deraadt kills me.
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/* $OpenBSD: signify.c,v 1.19 2014/01/09 19:05:21 tedu Exp $ */
/*
* Copyright (c) 2013 Ted Unangst <tedu@openbsd.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <sys/stat.h>
#include <netinet/in.h>
#include <resolv.h>
#include <stdint.h>
#include <fcntl.h>
#include <string.h>
#include <stdio.h>
#include <err.h>
#include <unistd.h>
#include <readpassphrase.h>
#include <util.h>
#include <sha2.h>
#include "crypto_api.h"
#define SIGBYTES crypto_sign_ed25519_BYTES
#define SECRETBYTES crypto_sign_ed25519_SECRETKEYBYTES
#define PUBLICBYTES crypto_sign_ed25519_PUBLICKEYBYTES
#define PKALG "Ed"
#define KDFALG "BK"
#define FPLEN 8
#define COMMENTHDR "untrusted comment: "
#define COMMENTHDRLEN 19
#define COMMENTMAXLEN 1024
struct enckey {
uint8_t pkalg[2];
uint8_t kdfalg[2];
uint32_t kdfrounds;
uint8_t salt[16];
uint8_t checksum[8];
uint8_t fingerprint[FPLEN];
uint8_t seckey[SECRETBYTES];
};
struct pubkey {
uint8_t pkalg[2];
uint8_t fingerprint[FPLEN];
uint8_t pubkey[PUBLICBYTES];
};
struct sig {
uint8_t pkalg[2];
uint8_t fingerprint[FPLEN];
uint8_t sig[SIGBYTES];
};
extern char *__progname;
static void
usage(void)
{
fprintf(stderr, "usage:"
#ifndef VERIFYONLY
"\t%s [-n] -p pubkey -s seckey -G\n"
"\t%s [-e] [-o output] -s seckey -S input\n"
#endif
"\t%s [-e] [-o output] -p pubkey -V input\n",
#ifndef VERIFYONLY
__progname, __progname,
#endif
__progname);
exit(1);
}
static int
xopen(const char *fname, int flags, mode_t mode)
{
int fd;
fd = open(fname, flags, mode);
if (fd == -1)
err(1, "open %s", fname);
return fd;
}
static void *
xmalloc(size_t len)
{
void *p;
p = malloc(len);
if (!p)
err(1, "malloc %zu", len);
return p;
}
static void
readall(int fd, void *buf, size_t len, const char *filename)
{
ssize_t x;
x = read(fd, buf, len);
if (x == -1) {
err(1, "read from %s", filename);
} else if (x != len) {
errx(1, "short read from %s", filename);
}
}
static size_t
parseb64file(const char *filename, char *b64, void *buf, size_t len,
char *comment)
{
int rv;
char *commentend, *b64end;
commentend = strchr(b64, '\n');
if (!commentend || commentend - b64 <= COMMENTHDRLEN ||
memcmp(b64, COMMENTHDR, COMMENTHDRLEN))
errx(1, "invalid comment in %s; must start with '%s'",
filename, COMMENTHDR);
*commentend = 0;
if (comment)
strlcpy(comment, b64 + COMMENTHDRLEN, COMMENTMAXLEN);
b64end = strchr(commentend + 1, '\n');
if (!b64end)
errx(1, "missing new line after b64 in %s", filename);
*b64end = 0;
rv = b64_pton(commentend + 1, buf, len);
if (rv != len)
errx(1, "invalid b64 encoding in %s", filename);
if (memcmp(buf, PKALG, 2))
errx(1, "unsupported file %s", filename);
return b64end - b64 + 1;
}
static void
readb64file(const char *filename, void *buf, size_t len, char *comment)
{
char b64[2048];
int rv, fd;
fd = xopen(filename, O_RDONLY | O_NOFOLLOW, 0);
memset(b64, 0, sizeof(b64));
rv = read(fd, b64, sizeof(b64) - 1);
if (rv == -1)
err(1, "read from %s", filename);
parseb64file(filename, b64, buf, len, comment);
memset(b64, 0, sizeof(b64));
close(fd);
}
uint8_t *
readmsg(const char *filename, unsigned long long *msglenp)
{
unsigned long long msglen;
uint8_t *msg;
struct stat sb;
int fd;
fd = xopen(filename, O_RDONLY | O_NOFOLLOW, 0);
fstat(fd, &sb);
msglen = sb.st_size;
if (msglen > (1UL << 30))
errx(1, "msg too large in %s", filename);
msg = xmalloc(msglen);
readall(fd, msg, msglen, filename);
close(fd);
*msglenp = msglen;
return msg;
}
static void
writeall(int fd, const void *buf, size_t len, const char *filename)
{
ssize_t x;
x = write(fd, buf, len);
if (x == -1) {
err(1, "write to %s", filename);
} else if (x != len) {
errx(1, "short write to %s", filename);
}
}
#ifndef VERIFYONLY
static void
appendall(const char *filename, const void *buf, size_t len)
{
int fd;
fd = xopen(filename, O_NOFOLLOW | O_RDWR | O_APPEND, 0);
writeall(fd, buf, len, filename);
close(fd);
}
static void
writeb64file(const char *filename, const char *comment, const void *buf,
size_t len, mode_t mode)
{
char header[1024];
char b64[1024];
int fd, rv;
fd = xopen(filename, O_CREAT|O_TRUNC|O_NOFOLLOW|O_RDWR, mode);
snprintf(header, sizeof(header), "%ssignify %s\n", COMMENTHDR,
comment);
writeall(fd, header, strlen(header), filename);
if ((rv = b64_ntop(buf, len, b64, sizeof(b64)-1)) == -1)
errx(1, "b64 encode failed");
b64[rv++] = '\n';
writeall(fd, b64, rv, filename);
memset(b64, 0, sizeof(b64));
close(fd);
}
static void
kdf(uint8_t *salt, size_t saltlen, int rounds, uint8_t *key, size_t keylen)
{
char pass[1024];
if (rounds == 0) {
memset(key, 0, keylen);
return;
}
if (!readpassphrase("passphrase: ", pass, sizeof(pass), 0))
errx(1, "readpassphrase");
if (bcrypt_pbkdf(pass, strlen(pass), salt, saltlen, key,
keylen, rounds) == -1)
errx(1, "bcrypt pbkdf");
memset(pass, 0, sizeof(pass));
}
static void
signmsg(uint8_t *seckey, uint8_t *msg, unsigned long long msglen,
uint8_t *sig)
{
unsigned long long siglen;
uint8_t *sigbuf;
sigbuf = xmalloc(msglen + SIGBYTES);
crypto_sign_ed25519(sigbuf, &siglen, msg, msglen, seckey);
memcpy(sig, sigbuf, SIGBYTES);
free(sigbuf);
}
static void
generate(const char *pubkeyfile, const char *seckeyfile, int rounds)
{
uint8_t digest[SHA512_DIGEST_LENGTH];
struct pubkey pubkey;
struct enckey enckey;
uint8_t xorkey[sizeof(enckey.seckey)];
uint8_t fingerprint[FPLEN];
SHA2_CTX ctx;
int i;
crypto_sign_ed25519_keypair(pubkey.pubkey, enckey.seckey);
arc4random_buf(fingerprint, sizeof(fingerprint));
SHA512Init(&ctx);
SHA512Update(&ctx, enckey.seckey, sizeof(enckey.seckey));
SHA512Final(digest, &ctx);
memcpy(enckey.pkalg, PKALG, 2);
memcpy(enckey.kdfalg, KDFALG, 2);
enckey.kdfrounds = htonl(rounds);
memcpy(enckey.fingerprint, fingerprint, FPLEN);
arc4random_buf(enckey.salt, sizeof(enckey.salt));
kdf(enckey.salt, sizeof(enckey.salt), rounds, xorkey, sizeof(xorkey));
memcpy(enckey.checksum, digest, sizeof(enckey.checksum));
for (i = 0; i < sizeof(enckey.seckey); i++)
enckey.seckey[i] ^= xorkey[i];
memset(digest, 0, sizeof(digest));
memset(xorkey, 0, sizeof(xorkey));
writeb64file(seckeyfile, "secret key", &enckey,
sizeof(enckey), 0600);
memset(&enckey, 0, sizeof(enckey));
memcpy(pubkey.pkalg, PKALG, 2);
memcpy(pubkey.fingerprint, fingerprint, FPLEN);
writeb64file(pubkeyfile, "public key", &pubkey,
sizeof(pubkey), 0666);
}
static void
sign(const char *seckeyfile, const char *msgfile, const char *sigfile,
int embedded)
{
struct sig sig;
uint8_t digest[SHA512_DIGEST_LENGTH];
struct enckey enckey;
uint8_t xorkey[sizeof(enckey.seckey)];
uint8_t *msg;
char comment[COMMENTMAXLEN], sigcomment[1024];
unsigned long long msglen;
int i, rounds;
SHA2_CTX ctx;
readb64file(seckeyfile, &enckey, sizeof(enckey), comment);
if (memcmp(enckey.kdfalg, KDFALG, 2))
errx(1, "unsupported KDF");
rounds = ntohl(enckey.kdfrounds);
kdf(enckey.salt, sizeof(enckey.salt), rounds, xorkey, sizeof(xorkey));
for (i = 0; i < sizeof(enckey.seckey); i++)
enckey.seckey[i] ^= xorkey[i];
memset(xorkey, 0, sizeof(xorkey));
SHA512Init(&ctx);
SHA512Update(&ctx, enckey.seckey, sizeof(enckey.seckey));
SHA512Final(digest, &ctx);
if (memcmp(enckey.checksum, digest, sizeof(enckey.checksum)))
errx(1, "incorrect passphrase");
memset(digest, 0, sizeof(digest));
msg = readmsg(msgfile, &msglen);
signmsg(enckey.seckey, msg, msglen, sig.sig);
memcpy(sig.fingerprint, enckey.fingerprint, FPLEN);
memset(&enckey, 0, sizeof(enckey));
memcpy(sig.pkalg, PKALG, 2);
snprintf(sigcomment, sizeof(sigcomment), "signature from %s", comment);
writeb64file(sigfile, sigcomment, &sig, sizeof(sig), 0666);
if (embedded)
appendall(sigfile, msg, msglen);
free(msg);
}
#endif
static void
verifymsg(uint8_t *pubkey, uint8_t *msg, unsigned long long msglen,
uint8_t *sig)
{
uint8_t *sigbuf, *dummybuf;
unsigned long long siglen, dummylen;
siglen = SIGBYTES + msglen;
sigbuf = xmalloc(siglen);
dummybuf = xmalloc(siglen);
memcpy(sigbuf, sig, SIGBYTES);
memcpy(sigbuf + SIGBYTES, msg, msglen);
if (crypto_sign_ed25519_open(dummybuf, &dummylen, sigbuf, siglen,
pubkey) == -1)
errx(1, "signature verification failed");
free(sigbuf);
free(dummybuf);
}
static void
verify(const char *pubkeyfile, const char *msgfile, const char *sigfile,
int embedded)
{
struct sig sig;
struct pubkey pubkey;
unsigned long long msglen, siglen = 0;
uint8_t *msg;
int fd;
msg = readmsg(embedded ? sigfile : msgfile, &msglen);
readb64file(pubkeyfile, &pubkey, sizeof(pubkey), NULL);
if (embedded) {
siglen = parseb64file(sigfile, msg, &sig, sizeof(sig), NULL);
msg += siglen;
msglen -= siglen;
} else {
readb64file(sigfile, &sig, sizeof(sig), NULL);
}
if (memcmp(pubkey.fingerprint, sig.fingerprint, FPLEN))
errx(1, "verification failed: checked against wrong key");
verifymsg(pubkey.pubkey, msg, msglen, sig.sig);
if (embedded) {
fd = xopen(msgfile, O_CREAT|O_TRUNC|O_NOFOLLOW|O_RDWR, 0666);
writeall(fd, msg, msglen, msgfile);
close(fd);
}
printf("verified\n");
free(msg - siglen);
}
int
main(int argc, char **argv)
{
const char *pubkeyfile = NULL, *seckeyfile = NULL, *msgfile = NULL,
*sigfile = NULL;
char sigfilebuf[1024];
int ch, rounds;
int embedded = 0;
enum {
NONE,
GENERATE,
SIGN,
VERIFY
} verb = NONE;
rounds = 42;
while ((ch = getopt(argc, argv, "GSVeno:p:s:")) != -1) {
switch (ch) {
#ifndef VERIFYONLY
case 'G':
if (verb)
usage();
verb = GENERATE;
break;
case 'S':
if (verb)
usage();
verb = SIGN;
break;
#endif
case 'V':
if (verb)
usage();
verb = VERIFY;
break;
case 'e':
embedded = 1;
break;
case 'n':
rounds = 0;
break;
case 'o':
sigfile = optarg;
break;
case 'p':
pubkeyfile = optarg;
break;
case 's':
seckeyfile = optarg;
break;
default:
usage();
break;
}
}
argc -= optind;
argv += optind;
#ifdef VERIFYONLY
if (verb != VERIFY)
#else
if (verb == NONE)
#endif
usage();
#ifndef VERIFYONLY
if (verb == GENERATE) {
if (!pubkeyfile || !seckeyfile || argc != 0)
usage();
generate(pubkeyfile, seckeyfile, rounds);
} else
#endif
{
if (argc != 1)
usage();
msgfile = argv[0];
if (!sigfile) {
if (snprintf(sigfilebuf, sizeof(sigfilebuf), "%s.sig",
msgfile) >= sizeof(sigfilebuf))
errx(1, "path too long");
sigfile = sigfilebuf;
}
#ifndef VERIFYONLY
if (verb == SIGN) {
if (!seckeyfile)
usage();
sign(seckeyfile, msgfile, sigfile, embedded);
} else
#endif
if (verb == VERIFY) {
if (!pubkeyfile)
usage();
verify(pubkeyfile, msgfile, sigfile, embedded);
}
}
return 0;
}