File: [local] / src / usr.bin / signify / signify.c (download)
Revision 1.4, Tue Dec 31 03:54:05 2013 UTC (10 years, 5 months ago) by tedu
Branch: MAIN
Changes since 1.3: +2 -2 lines
another last minute bug i introduced. found by jturner
|
/* $OpenBSD: signify.c,v 1.4 2013/12/31 03:54:05 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 streq(a, b) (strcmp(a, b) == 0)
#define SIGBYTES crypto_sign_ed25519_BYTES
#define SECRETBYTES crypto_sign_ed25519_SECRETKEYBYTES
#define PUBLICBYTES crypto_sign_ed25519_PUBLICKEYBYTES
#define PKALG "Ed"
#define KDFALG "BK"
struct enckey {
uint8_t pkalg[2];
uint8_t kdfalg[2];
uint32_t kdfrounds;
uint8_t salt[16];
uint8_t checksum[8];
uint8_t seckey[SECRETBYTES];
};
struct pubkey {
uint8_t pkalg[2];
uint8_t pubkey[PUBLICBYTES];
};
struct sig {
uint8_t pkalg[2];
uint8_t sig[SIGBYTES];
};
extern char *__progname;
static void
usage(void)
{
fprintf(stderr, "usage: %s [-N] [-I input] [-P pubkey] [-S seckey] "
"-V generate|sign|verify\n", __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)
{
if (read(fd, buf, len) != len)
err(1, "read");
}
static void
readb64file(const char *filename, void *buf, size_t len)
{
char b64[2048];
int i, 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 in %s", filename);
for (i = 0; i < rv; i++)
if (b64[i] == '\n')
break;
if (i == rv)
errx(1, "no newline in %s", filename);
rv = b64_pton(b64 + i, buf, len);
if (rv != len)
errx(1, "invalid b64 encoding in %s", filename);
memset(b64, 0, sizeof(b64));
close(fd);
if (memcmp(buf, PKALG, 2))
errx(1, "unsupported file %s", filename);
}
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);
close(fd);
*msglenp = msglen;
return msg;
}
static void
writeall(int fd, const void *buf, size_t len)
{
if (write(fd, buf, len) != len)
err(1, "write");
}
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_EXCL|O_NOFOLLOW|O_RDWR, mode);
snprintf(header, sizeof(header), "signify -- %s\n", comment);
writeall(fd, header, strlen(header));
if ((rv = b64_ntop(buf, len, b64, sizeof(b64))) == -1)
errx(1, "b64 encode failed");
writeall(fd, b64, rv);
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
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 failed");
free(sigbuf);
free(dummybuf);
}
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)];
SHA2_CTX ctx;
int i;
crypto_sign_ed25519_keypair(pubkey.pubkey, enckey.seckey);
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);
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);
writeb64file(pubkeyfile, "public key", &pubkey,
sizeof(pubkey), 0666);
}
static void
sign(const char *seckeyfile, const char *inputfile, const char *sigfile)
{
struct sig sig;
uint8_t digest[SHA512_DIGEST_LENGTH];
struct enckey enckey;
uint8_t xorkey[sizeof(enckey.seckey)];
uint8_t *msg;
unsigned long long msglen;
int i, rounds;
SHA2_CTX ctx;
readb64file(seckeyfile, &enckey, sizeof(enckey));
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(inputfile, &msglen);
signmsg(enckey.seckey, msg, msglen, sig.sig);
memset(&enckey, 0, sizeof(enckey));
memcpy(sig.pkalg, PKALG, 2);
writeb64file(sigfile, "signature", &sig, sizeof(sig), 0666);
free(msg);
}
static void
verify(const char *pubkeyfile, const char *inputfile, const char *sigfile)
{
struct sig sig;
struct pubkey pubkey;
unsigned long long msglen;
uint8_t *msg;
readb64file(pubkeyfile, &pubkey, sizeof(pubkey));
readb64file(sigfile, &sig, sizeof(sig));
msg = readmsg(inputfile, &msglen);
verifymsg(pubkey.pubkey, msg, msglen, sig.sig);
printf("verified\n");
free(msg);
}
int
main(int argc, char **argv)
{
const char *verb = NULL;
const char *pubkeyfile = NULL, *seckeyfile = NULL, *inputfile = NULL,
*sigfile = NULL;
char sigfilebuf[1024];
int ch, rounds;
rounds = 42;
while ((ch = getopt(argc, argv, "I:NO:P:S:V:")) != -1) {
switch (ch) {
case 'I':
inputfile = optarg;
break;
case 'N':
rounds = 0;
break;
case 'O':
sigfile = optarg;
break;
case 'P':
pubkeyfile = optarg;
break;
case 'S':
seckeyfile = optarg;
break;
case 'V':
verb = optarg;
break;
default:
usage();
break;
}
}
argc -= optind;
if (argc != 0 || verb == NULL)
usage();
if (inputfile && !sigfile) {
if (snprintf(sigfilebuf, sizeof(sigfilebuf), "%s.sig",
inputfile) >= sizeof(sigfilebuf))
errx(1, "path too long");
sigfile = sigfilebuf;
}
if (streq(verb, "generate")) {
if (!pubkeyfile || !seckeyfile)
usage();
generate(pubkeyfile, seckeyfile, rounds);
} else if (streq(verb, "sign")) {
if (!seckeyfile || !inputfile)
usage();
sign(seckeyfile, inputfile, sigfile);
} else if (streq(verb, "verify")) {
if (!pubkeyfile || !inputfile)
usage();
verify(pubkeyfile, inputfile, sigfile);
} else {
usage();
}
return 0;
}