int main(int argc, char **argv)
{
unsigned char *argbuf;
size_t argbuflen;
gcry_mpi_t our_x, our_y, their_y;
unsigned char *pubbuf;
size_t publen;
unsigned char sessionid[20], sendenc[16], rcvenc[16];
unsigned char sendmac[20], rcvmac[20];
int is_high;
if (argc != 3) {
usage(argv[0]);
}
argv_to_buf(&argbuf, &argbuflen, argv[1]);
/* Private keys are only 320 bits long, so check for that to make
* sure they didn't get the args the wrong way around */
if (!argbuf || argbuflen > 40) usage(argv[0]);
gcry_mpi_scan(&our_x, GCRYMPI_FMT_USG, argbuf, argbuflen, NULL);
free(argbuf);
argv_to_buf(&argbuf, &argbuflen, argv[2]);
if (!argbuf) usage(argv[0]);
gcry_mpi_scan(&their_y, GCRYMPI_FMT_USG, argbuf, argbuflen, NULL);
free(argbuf);
sesskeys_gen(sessionid, sendenc, rcvenc, &is_high, &our_y, our_x, their_y);
sesskeys_make_mac(sendmac, sendenc);
sesskeys_make_mac(rcvmac, rcvenc);
/* Print our public key into a buffer */
gcry_mpi_print(GCRYMPI_FMT_USG, NULL, 0, &publen, our_y);
pubbuf = malloc(publen);
if (!pubbuf) {
fprintf(stderr, "Out of memory!\n");
exit(1);
}
gcry_mpi_print(GCRYMPI_FMT_USG, pubbuf, publen, NULL, our_y);
puts("");
printf("We are the %s end of this key exchange.\n",
is_high ? "high" : "low");
puts("");
dump_data(stdout, "Our public key", pubbuf, publen);
puts("");
dump_data(stdout, "Session id", sessionid, 20);
puts("");
dump_data(stdout, "Sending AES key", sendenc, 16);
dump_data(stdout, "Sending MAC key", sendmac, 20);
dump_data(stdout, "Receiving AES key", rcvenc, 16);
dump_data(stdout, "Receiving MAC key", rcvmac, 20);
puts("");
fflush(stdout);
return 0;
}
int main(int argc, char **argv)
{
unsigned char *argbuf;
size_t argbuflen;
unsigned char mackey[20];
if (argc != 2) {
usage(argv[0]);
}
argv_to_buf(&argbuf, &argbuflen, argv[1]);
/* AES keys are 128 bits long, so check for that */
if (!argbuf) {
usage(argv[0]);
}
if (argbuflen != 16) {
fprintf(stderr, "The AES key must be 32 hex chars long.\n");
usage(argv[0]);
}
sesskeys_make_mac(mackey, argbuf);
dump_data(stdout, "AES key", argbuf, 16);
dump_data(stdout, "MAC key", mackey, 20);
free(argbuf);
fflush(stdout);
return 0;
}
int main(int argc, char **argv)
{
unsigned char *mackey;
size_t mackeylen;
unsigned char macval[20];
char *otrmsg = NULL;
DataMsg datamsg;
size_t textlen;
unsigned int offset;
const unsigned char *old_text, *new_text;
char *newdatamsg;
size_t i;
if (argc != 5) {
usage(argv[0]);
}
argv_to_buf(&mackey, &mackeylen, argv[1]);
if (!mackey) {
usage(argv[0]);
}
if (mackeylen != 20) {
fprintf(stderr, "The MAC key must be 40 hex chars long.\n");
usage(argv[0]);
}
textlen = strlen(argv[2]);
if (textlen != strlen(argv[3])) {
fprintf(stderr, "The old_text and new_text must be of the same "
"length.\n");
usage(argv[0]);
}
old_text = (const unsigned char *)argv[2];
new_text = (const unsigned char *)argv[3];
if (sscanf(argv[4], "%u", &offset) != 1) {
fprintf(stderr, "Unparseable offset given.\n");
usage(argv[0]);
}
otrmsg = readotr(stdin);
if (otrmsg == NULL) {
fprintf(stderr, "No OTR Data Message found on stdin.\n");
exit(1);
}
if (otrl_proto_message_type(otrmsg) != OTRL_MSGTYPE_DATA) {
fprintf(stderr, "OTR Non-Data Message found on stdin.\n");
exit(1);
}
datamsg = parse_datamsg(otrmsg);
free(otrmsg);
if (datamsg == NULL) {
fprintf(stderr, "Invalid OTR Data Message found on stdin.\n");
exit(1);
}
/* Check the MAC */
sha1hmac(macval, mackey, datamsg->macstart,
datamsg->macend - datamsg->macstart);
if (memcmp(macval, datamsg->mac, 20)) {
fprintf(stderr, "MAC does not verify: wrong MAC key?\n");
exit(1);
}
/* Modify the ciphertext */
for(i=0; i<textlen && offset+i < datamsg->encmsglen; ++i) {
datamsg->encmsg[offset+i] ^= (old_text[i] ^ new_text[i]);
}
/* Recalculate the MAC */
newdatamsg = remac_datamsg(datamsg, mackey);
printf("%s\n", newdatamsg);
free(newdatamsg);
free_datamsg(datamsg);
free(mackey);
fflush(stdout);
return 0;
}