Advanced PDF Password Recovery (or APDFPR for short) is intended to decrypt password-protected and restricted Adobe Acrobat PDF files that have "user" password (required to open/view the file) and/or "owner" password set (when the file is only protected from editing, printing etc), i.e. remove the protection and/or break the PDF password. Restricted files are being unprotected instantly, whereas decryption of files with "open" password may be time-consuming. The program is also able to convert Kinko's Document Format (KDF) files to PDF files (without any protection).
The versions (editions) are available: Standard, Professional, and Enterprise.
Standard edition is only able to remove restrictions (from printing, selecting text and graphics and copying them into the Clipboard, adding/changing annotations and form fields). It does not handle PDF files with "open" password set, if that password is not known.
Professional edition has all functionality of the Standard one, but also allows to search for "owner" and "user" passwords with brute-force and dictionary attacks optimized for speed. In addition, it implements a key search attack, which guarantees decryption (regardless of password length and complexity) of PDF files that use 40-bit encryption. This attack takes from a few days (on modern dual-core systems) and up to two weeks (on older computers).
Finally, Enterprise edition adds an improved key search attack using state-of-the-art "time-memory trade-off" or revised "rainbow tables" technique, allowing to break "user" password (for 40-bit encryption) in just a few minutes (instead of days, as in Professional edition), using special pre-computed tables on DVD, shipped with express mail. The success rate is 100% (unlike with traditional "rainbow tables").
All editions of APDFPR support files created with Adobe Acrobat versions 3.x through 8.x that use 40-bit RC4, 128-bit RC4, AES, or no encryption.
Guaranteed PDF Decryptor (GuaPDF) by Pavel Semjanov
This is a GUI and command-line utility to remove operation restrictions (printing, changing, etc.) on PDF files - instantly.
GuaPDF can also decrypt PDF files protected with any password for opening by testing all 40-bit RC4 keys. This may take a few days.
PDFCrack is a command-line tool for recovering passwords and content from PDF files. It is small and it has no external dependencies. PDFCrack is currently distributed in source code form only, and it is known to compile and run on GNU/Linux systems.
PDFCrack supports the standard security handler (revisions 2, 3, and 4) on all known PDF versions, and it supports cracking both owner and user passwords, with optimized search for owner password when the user password is known. PDFCrack can read candidate passwords from a wordlist (optionally applying simple permutations) or do an exhaustive search, and it is able to recover and continue an interrupted password cracking job.