PdfCrypt is a windows 32 console/command line version PDF encrypt & decrypt software, supports standard 48 bits, 128 bits, AES-128 bits encryption, and decryption. And first of all,it is free.
Download now(1.84M).
If you need java source code, linux stand alone version, or .net version, please let me know.
It bases on modified version iText 1.5.4 and gcj [...]