dryriver writes: Translated from Der Spiegel: Hamburg Data-Protection Specialist Johannes Caspar warns against using iPhone 5S's new Fingerprint ID function. "The biometric features of your body, like your fingerprints, cannot be erased or deleted. They stay with you until the end of your life and stay constant — they cannot be changed. One should thus avoid using biometric ID technologies for non-vital or casual everyday uses like turning on a smartphone. This is especially true if a biometric ID, like your fingerprint, is stored in a data file on the electronic device you are using." Caspar finds Apple's argument that "your fingerprint is only stored on the iPhone, never transmitted over the network" weak and misleading. "The average iPhone user is not capable of checking, on a technical level, what happens to his or her fingerprint once it is on the iPhone. He or she cannot tell with any certainty or ease what kind of private data applications downloaded onto the iPhone can or cannot access. The recent disclosure of spying programs like Prism makes it riskier than ever before to share important personal data with electronic devices." Caspar adds: "As a matter of principle, one should never hand over any biometric data when it isn't strictly needed. Handing over a non-changeable biometric feature like a fingerprint for no better reason than that it provides 'some convenience' in everyday use, is ill advised and foolish. One must always be extremely cautious where and for what reasons one hands over biometric features."