program is computing sha1('!n00bsh1t!' + argv[1]) and expecting hash '2d843092871bbd0a08bd003d38d0dae5107d9bd4' brute force with hashcat and solution is: $ echo -n '!n00bsh1t!w33dz' |sha1sum 2d843092871bbd0a08bd003d38d0dae5107d9bd4 *- flag is md5 of input: $ echo -n 'w33dz' |md5sum e12e4b46dff1b6c996244fb70e5ca2b0 *-