Requirements
•Windows OS (from Windows 2000 to Windows 10)
•about 6 megabytes of free space on hard disk (4 gigabytes for Enterprise version)
Limitations
•PDF files protected using Digital Rights Management (DRM) technology or 3rd party plugins such as FileOpen cannot be decrypted. If you try to start to decrypt such file, APDFPR shows the message like:
•Brute-force attack is effective for short passwords only, usually up to 7-8 chars. Recovering longer ones will take too much time (months, years) even on a very fast computer. In most cases, dictionary attack really helps (to find long passwords), but if the password is well-selected (e.g. the combination of letters, digits and special chars, or concatenation of two or more words etc), it cannot be recovered at all. Fortunately, if only "owner" password is set, there is no need to recover it at all – the document can be decrypted (instantly) anyway; and for files with "user" password that use 40-bit encryption, you can use Key search attack.
•The program tries to process corrupted files (and on success, shows the number of non-critical errors ignored), but sometimes, it is not possible. You can fix most of such problems simply by opening your file in Adobe Acrobat (full version, not the Reader) and just saving it without making any changes.
