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#include <mhash.h>
#include <fcntl.h>
#define KEYSIZE 16
#define PASSSIZE 4
#define HASH_ALGORITHM MHASH_SHA256
#define HASH_BLOCKSIZE 32
#define KEYGEN_ALGORITHM KEYGEN_MCRYPT
int uw_hash_blocksize = HASH_BLOCKSIZE;
static int password[PASSSIZE];
static unsigned char private_key[KEYSIZE];
char *uw_sig_file = NULL;
static void random_password() {
int i;
for (i = 0; i < PASSSIZE; ++i)
password[i] = rand();
}
void uw_init_crypto() {
KEYGEN kg = {{HASH_ALGORITHM, HASH_ALGORITHM}};
assert(mhash_get_block_size(HASH_ALGORITHM) == HASH_BLOCKSIZE);
if (uw_sig_file) {
int fd;
if (access(uw_sig_file, F_OK)) {
random_password();
if ((fd = open(uw_sig_file, O_WRONLY | O_CREAT, 0700)) < 0) {
fprintf(stderr, "Can't open signature file %s\n", uw_sig_file);
perror("open");
exit(1);
}
if (write(fd, &password, sizeof password) != sizeof password) {
fprintf(stderr, "Error writing signature file\n");
exit(1);
}
close(fd);
} else {
if ((fd = open(uw_sig_file, O_RDONLY)) < 0) {
fprintf(stderr, "Can't open signature file %s\n", uw_sig_file);
perror("open");
exit(1);
}
if (read(fd, &password, sizeof password) != sizeof password) {
fprintf(stderr, "Error reading signature file\n");
exit(1);
}
close(fd);
}
} else
random_password();
if (mhash_keygen_ext(KEYGEN_ALGORITHM, kg,
private_key, sizeof(private_key),
(unsigned char*)password, sizeof(password)) < 0) {
fprintf(stderr, "Key generation failed\n");
exit(1);
}
}
void uw_sign(const char *in, char *out) {
MHASH td;
td = mhash_hmac_init(HASH_ALGORITHM, private_key, sizeof(private_key),
mhash_get_hash_pblock(HASH_ALGORITHM));
mhash(td, in, strlen(in));
if (mhash_hmac_deinit(td, out) < 0)
fprintf(stderr, "Signing failed\n");
}
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