Looks like Apple, Inc. added cryptographic checksums to their latest iPod firmware and locks out competitors and home-made programs from using it.
"A Method for Obtaining Digital Signatures and Public-Key Cryptosystems", Ronald L. Rivest, Adi Shamir, and Leonard M. Adleman. PDF reprint of: CACM 21/2, pp. 120-126 » . The original paper on RSA (and the birth of Alice and Bob).
"Verschlüsselte E-Mails kein Indiz für Mitgliedschaft in einer terroristischen Vereinigung". no shit, sherlock.