rem: sum_init();
add: sum_init(0);
context: static void gen_challenge(char *addr, char *challenge){	char input[32];	struct timeval tv;	memset(input, 0, sizeof input);	strlcpy((char *)input, addr, 17);	sys_gettimeofday(&tv);	SIVAL(input, 16, tv.tv_sec);	SIVAL(input, 20, tv.tv_usec);	SIVAL(input, 24, getpid());	sum_init();	sum_update(input, sizeof input);	sum_end(challenge);}