Perl script to remove protection from a PDF.

gistfile1.txt

# Usage: perl invalidate-signing-certs.pl <in.pdf >out.pdf
binmode(STDIN);
binmode(STDOUT);
$/ = "\0";
while(<>) {
  s#(/Perms<</DocMDP.*?>>)#' ' x length $1#ge;
  s#(/Ff 1)(?=.*?/Lock )#' ' x length $1#ge;
  s#(?<=/Lock)(.*?)(/Ff 1)#"$1" . ' ' x length $2#ge;
  s#(/Lock .*?)(?=/)#' ' x length $1#ge;
  s#( obj<<)([^>\rendobj)#$1 . (‘ ‘ x length $2) . $3#ge;
  print $_;
}