How to remove restrictions/password from a PDF
Comments (0) Adobe Acrobat PDF documents have a nice feature which allows content authors to restrict certain features or “encrypt” the document using a password. These can all be easily bypassed using the open-source Ghostscript:
gs -q -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sOutputFile=unencrypted.pdf -c .setpdfwrite -f encrypted.pdf
Source : http://www.cyberciti.biz/faq/removing-password-from-pdf-on-linux/
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