Security passwords on PDF files

Last Reviewed: June 12, 2008

Article: DTS0161

Applies to: dtSearch 7

Some PDF files may be reported as encrypted during indexing, even though no password is needed to open the file.  This can occur because encryption is sometimes used in PDF files to enforce restrictions on printing or extracting text from a PDF file.

PDF files can have two kinds of passwords:
(1) A password that prevents any access to the file unless the user enters a password before opening it in Adobe Reader.  dtSearch cannot index files with this type of encryption at all.

(2) A password that prevents certain operations (printing, editing, etc.) only. This type of PDF file can be opened in Adobe Reader with no need to enter a password, but you may not be able to print the PDF file or copy text to the clipboard from the PDF file.  dtSearch can index this type of PDF file only if the encryption level is 40-bit (RC4).   If higher-level encryption is used, then dtSearch cannot access the text in the PDF file.

To tell what kind of encryption is used in a PDF file, open the PDF file in Adobe Reader and click File > Document Properties, and click the Security tab.

A workaround that may help in some cases is to temporarily remove the security password, or to remove the password on a temporary copy of the files, and to index the unencrypted files and then replace them with the original encrypted files.   dtSearch does not require access to the original files to search or display PDF files, so restoring the encrypted versions after indexing will not affect dtSearch.   Adobe Acrobat has a "batch processing" function that can be used to remove and restore encryption from many PDF files in one step.