Validate pubkey hash address for main Bitcoin network in Perl

Base58Check.pm

#!/usr/bin/env perl
# check if string looks like a valid pubkey hash address for main Bitcoin network
# klg, Aug 2013
package Base58Check;
use strict;
use bytes;
use Carp;
use Digest::SHA 'sha256';
use Math::BigInt;

use constant BASE58 =>
  '123456789ABCDEFGHJKLMNPQRSTUVWXYZabcdefghijkmnopqrstuvwxyz';

sub decode(;$) {
  $_ = shift // $_ // ''; s/\s//g;
  my $z = length((m/^(1*+)/)[0]);
  my ($x, @x) = Math::BigInt->bzero;
  $x->bmul(58)->badd(index BASE58, $_) for split //;
  unshift @x, ($x->bdiv(256))[1] while $x;
  $_ = "\0" x $z . pack 'C*', @x;
  croak 'Base58Check invalid' unless substr($_, (length)-4) eq
    substr(sha256(sha256 substr $_, 0, (length)-4), 0, 4);
  $_ = substr $_, 0, (length) - 4;
}

sub valid($) {
  $_ = shift // $_;
  eval {
    Base58Check::decode;
    length == 21 and ord == 0;
  };
}


package test;
print "ok\n" if Base58Check::valid '13gdq5b3uq1T6Hdq8137wxJHz7jXHSDPXa';
# $_ eq "0" . ripemd160(sha256(pubkey))

1;