PDF document security will be created using digital signatures and document-access control using public key infrastructure, a form of cryptography.
Through PKI, users of the new technology can ensure that the sender is who he or she claims to be and that the content of the document hasn't been changed. For instance, the recipient of a contract created in Acrobat and digitally signed with digital credentials stored on IBM's security chip would have high assurance that the document was legitimate. Because the private security credentials remain secure on the chip, they're much more difficult for hackers to tamper with than digital certificates sitting open on a hard drive.
Adobe Acrobat 6.0 began shipping in May.