dtmp = silc_calloc((3 * hash_len), sizeof(unsigned char));
memcpy(dtmp, k1, hash_len);
memcpy(dtmp + hash_len, k2, hash_len);
dtmp = silc_calloc((3 * hash_len), sizeof(unsigned char));
memcpy(dtmp, k1, hash_len);
memcpy(dtmp + hash_len, k2, hash_len);