#define AIM_MD5_STRING "AOL Instant Messenger (SM)"

   /* calculate md5-hash to send to server */
   md5_init(&state);
   md5_append(&state, (const md5_byte_t *)authkey, strlen(authkey));
   md5_append(&state, (const md5_byte_t *)passwd, strlen(passwd));
   md5_append(&state, (const md5_byte_t *)AIM_MD5_STRING, strlen(AIM_MD5_STRING));
   md5_finish(&state, (md5_byte_t *)auth_hash);
 
   /* Now we ready send to server auth_hash array (16 bytes long) */