There is a perl 5 sha1.pl which you can rename to sha1 and put somewhere in
your path if you can't compile for some reason.  Only short strings are
sha1'd by the eternity server, so it shouldn't affect performance greatly.

Or compile with "source compiling" or ". compiling" depending on your shell.

In either case (compiled or sha1.pl) put the path to your sha1 in 
eternity.conf
