PDF security overview
The standard PDF protection can have two different passwords: a document open password and a permissions password. When a document open password (also known as a user password) is set, anyone who tries to open the PDF must type in the password. When a permissions password (also known as a master or owner password) is set, recipients don't need a password to open the document, but they must type the permissions password to set or change the restricted features. PDF security supports encryption with 40, 128 and 256 bit keys.
* GuaPDF is the remover of PDF restrictions (permissions password). It is instant and guaranteed process.
* GuaPDF is also the remover of PDF open password. It is guaranteed only if it has 40-bit key long, it takes about a day.
* Password recovery of 128 or 256-bit PDF encryption is only possible using PDF brute force software..