is it possible to check if pdf is password protected using ghostscript?

is it possible to check if pdf is password protected using ghostscript? what would be the command? 开发者_如何转开发 I know you can strip pdf password using ghostscript, but all I want to do is just checking if PDF is password protected or security enabled.

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checkuserpasswdPDF.sh:

#!/bin/sh

GS=~/gs/bin/gs
output=`$GS -dBATCH -sNODISPLAY "$1" 2>&1`
gsexit=$?

if [ "$gsexit" == "0" ]; then
  echo "Not user-password protected"
  exit 0;
else
  found=`echo "$output" |grep -o "This file requires a password"`
  if [ -z "$found" ]; then
    echo "Failed to invoke gs" 
    exit $gsexit
  else
    echo "Protected"
    exit 0;
  fi  
fi

Checks for user-password protected PDFs: checkuserpasswdPDF.sh test.pdf.

GS disregards owner-passwords (see this).

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With pdftk it is possible to detect a user password or owner password by just trying to do a dump_data operation.

 protected=0
 pdftk "input.pdf" dump_data output /dev/null dont_ask || protected=1

The problem here is that you don't know what the password prevents: reading, extracting data, modifying...?

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Using a bat file, you can do a little workaround by searching for "Encrypt" in the pdfs. Its quiet fast to search through many files.

Findstr /M /I "Encrypt" *.pdf 

This will return all filenames that are secured (since "Encrypt" will be written in the file as dos reads it)

Maybe this is something someone can use. I use:
for /f %%a in ('Findstr /M /I "Encrypt" *.pdf') do move %%a c:\tempfiles\
to move all secured pdf's to c:\tempfiles. From there I use ghostscript to remove the security, and move it back to original folder.

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You can test using pdfinfo

pdfinfo $filename &>/dev/null;
if [[ $? -eq 1 ]] ; then
   echo "File can not be opened for reading"
fi

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The answer of @Benoit gives ugly errors on console, but works.

So I would put this to an oneliner with suppression of error output:

protected=0 && pdftk "input.pdf" dump_data output /dev/null dont_ask 2>/dev/null || protected=1