Generating the payment request form using Perl

Created by Richard Moore, Modified on Wed, 12 Apr, 2023 at 12:02 PM by Richard Moore
To generate the payment request form using Perl please see the code below:
#!/usr/bin/perl -w

use strict;


# Prerequisites
# In order to be able to calculate the HMAC MD5 digest, we use a function hmac_md5_hex below.
# 
#  1. Install Digest::MD5 from http://cpan.uwinnipeg.ca/dist/Digest-Perl-MD5
#  2. Install Digest::HMAC_MD5 from http://theoryx5.uwinnipeg.ca/pub/CPAN/authors/id/G/GA/GAAS/Digest-HMAC-1.01.tar.gz
# Other perl packages may be available
#
# With CPAN :
#
# (sudo) perl -MCPAN -e shell;
# install Digest::MD5
# install Digest::HMAC_MD5
# install Digest::SHA1
# exit
#
# Note: Digest::SHA1
# this will also install Digest::HMAC_SHA1

use Digest::HMAC_SHA1 qw(hmac_sha1_hex);

print "content-type: text/html\n\n";

print <<END_HEADER;
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd" >
<html>
  <head>
    <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
    <title>
      Hosted Checkout: Sample Perl Payment Form with SHA-1
    </title>
    <style type="text/css">
      label {
          display: block;
          margin: 5px 0px;
          color: #AAA;
       }
       input {
          display: block;
       }
       input[type=submit] {
          margin-top: 20px;
       }
    </style>

  </head>
  <body>

  <h1>
    Hosted Checkout: Sample Perl Payment Form with SHA-1
  </h1>

  <form action="https://checkout.e-xact.com/pay" method="POST">
END_HEADER


      my $x_amount = "595.99";
      my $x_login = "WSP-#####-##";  # Take from Payment Page ID in Payment Pages interface
      my $transaction_key = "###############"; # Take from Payment Pages configuration interface
      my $x_currency_code = "CAD"; # Needs to agree with the currency of the payment page
      my $x_fp_sequence = int(rand 5000) + 1000;
      my $x_fp_timestamp = time; #  needs to be in UTC. Make sure webserver produces UTC

      #  The values that contribute to x_fp_hash 
      my $hmac_data = $x_login . "^" . $x_fp_sequence . "^" . $x_fp_timestamp . "^" . $x_amount . "^" . $x_currency_code;

      my $x_fp_hash = hmac_sha1_hex($hmac_data, $transaction_key);

      print('<label>x_login</label> <input name="x_login" value="' . $x_login . '">' );
      print('<label>x_amount</label> <input name="x_amount" value="' . $x_amount . '">' );
      print('<label>x_fp_sequence</label> <input name="x_fp_sequence" value="' . $x_fp_sequence . '">' );
      print('<label>x_fp_timestamp</label> <input name="x_fp_timestamp" value="' . $x_fp_timestamp . '">' );
      print('<label>x_fp_hash (with SHA-1)</label> <input name="x_fp_hash" value="' . $x_fp_hash . '" size="50">' );
      print('<label>x_currency_code</label> <input type="hidden" name="x_currency_code" value="' . $x_currency_code . '">');

     print <<END_REST
      <input type="hidden" name="x_show_form" value="PAYMENT_FORM">
      <input type="hidden" name="x_test_request" value="TRUE"> 

      <input type="submit" value="Pay with Hosted Checkout">
    </form>

  </body>
</html>
END_REST