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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).
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
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!).
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:
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
.
PDF requires password for copying document contents
Error code 1.4.2^*^.
PDF requires password for printing
Error code 1.4.2^*^.
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).
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
References
References to literature, etc.