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h2. Description
PDF permits the use of encryption as a means of restricting access or (re-)use of content. This may range from documents that can only be opened after providing a password, to disabling specific functionality (e.g. printing, copying content).

h2. Risks
* Content may become inaccessible if passwords are not known (even though "cracking" is often technically possible, institutions may not be legally permitted to do this)
* Printing / copy restrictions may complicated any future preservation actions

h2. Assessment

The _Preflight_ component of [Apache PDFBox] (an open source _PDF/A_ validator) is able to detect encryption in a PDF (_any_ PDF, doesn't have to be _PDF/A_!).

h3. PDF requires password for opening

In _Preflight_ 1.8.0 an open password results in error code 1.0 (syntax error), accompanied by this description:

bq. Syntax error, Error (CryptographyException) while creating security handler for decryption: Error: The supplied password does not match either the owner or user password in the document

In _Preflight_ 2.0.0 only a 'syntax' error message is reported without any indication of anything encryption-related. Reported this as a [bug|https://issues.apache.org/jira/browse/PDFBOX-1659].

h3. PDF requires password for copying document contents

Error code 1.4.2^*^.

h3. PDF requires password for printing

Error code 1.4.2^*^.

h3. PDF requires password to enable text access for screen reader devices for the visually impaired.

Error code 1.4.2^*^.


^*^: based on _Preflight_ 1.8.0. In 2.0.0 an error code 1.0 with a 'syntax error' message is produced, but this looks like a bug (see above).

h2. Example files

* [http://www.opf-labs.org/format-corpus/pdfCabinetOfHorrors/encryption_openpassword.pdf] - Requires password to open the file
* [http://www.opf-labs.org/format-corpus/pdfCabinetOfHorrors/encryption_nocopy.pdf] - Requires password to copy document contents
* [http://www.opf-labs.org/format-corpus/pdfCabinetOfHorrors/encryption_noprinting.pdf] - Requires password for printing
* [http://www.opf-labs.org/format-corpus/pdfCabinetOfHorrors/encryption_notextaccess.pdf] - Requires password to enable text access for screen reader devices for the visually impaired

h2. References
References to literature, etc.