You could get the benefit of a peer reviewed algorithm by using some secret salt (which was suggested by Fletch in Re^6: monastery mark-upedness (brute force)). 

use Digest::SHA1 qw( sha1_hex );

my $ip_address = shift;
my $secret_salt = q{you don't know this part};

my $published_hash = sha1_hex( $ip_address . $secret_salt );

[download]

Someone who has access to the source could launch a dictionary attack now, but that would be true if the source had a roll-your-own algorithm too.

In reply to Re^11: monastery mark-upedness (privacy) by kyle
in thread monastery mark-upedness by my_nihilist

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