Our contract states they cannot change code without my permission.

This won't help with the scripts that you're currently locked out of, but in the future, build in a command to return (e.g., as "text/plain") a set of MD5 hashes, one for each of your components. To prevent your customers from simply replacing that command with a hard-coded print of the "correct" hashes, pass a parameter to the command, use the parameter to generate a new hash. E.g., 

    my $nonce = param('nonce');
    ...
    my $md5_script = md5_hex($script_body);
    my $md5 = md5_hex($md5_script . $nonce);
    print "$script: $md5\n";

[download]
Then, assuming you have an identical copy of the source on hand, pick a random number, calculate the hash values for your copy of the surce files, then pass that random value to the remove CGI, comparing the values that it returns.

In reply to Re: OT: Getting at source code of CGI scripts by dws
in thread OT: Getting at source code of CGI scripts by Anonymous Monk

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