% rc4 hexkey < input > output
#define S ,t=s[i],s[i]=s[j],s[j]=t /* rc4 hexkey <file */
unsigned char k[256],s[256],i,j,t;main(c,v,e)char**v;{++v;while(++i)s[ 
i]=i;for(c=0;*(*v)++;k[c++]=e)sscanf((*v)++-1,"%2x",&e);while(j+=s[i]
+k[i%c]S,++i);for(j=0;c=~getchar();putchar(~c^s[t+=s[i]]))j+=s[++i]S;}

use Digest::MD4 md4_hex;
 
my $goal = '8c91a67ef3a47031ec08830327848826'; # hash to find
my @chars = ( a..z, 0..9 ); # characters to use
my $minlen = 1; # minimum length of string
my $maxlen = 8; # maximum length of string
 
for ( $minlen..$maxlen ) {
	print 'Length: ', $_, "\n";
	&checkStrings($_);
}
 
sub checkStrings {
	my ( $n, $s ) = ( (shift) - 1, shift );
	for ( @chars ) {
		if ( $n ) {
			checkStrings($n, $s . $_ );
		} else {
			print $s, $_, "\n" if md4_hex( $s . $_ ) eq $goal;
		}
	}
}