Re:Why put ANY data on passports? (Score 2, Interesting)

The reason is quicker transfer of more data (high resolution pictures of your face, biometric information like fingerprints) than can be achieved with the paper version.

It should be noted that it is only the US that does not deploy "basic access control", which effectively locks out RFID readers unless they can optically read the passport (e.g. it is on the scanner).

Europe and Japan are implementing this privacy protection. The irony is that especially for US citizens the threat of identity theft is (still?) much higher then for European and Japanese citizens...

Technically: the access to the data requires successful authentication against a hash of the four lines of data on your passport ("MRZ") and setup of an encrypted tunnel ("secure messaging" in smartcard terminology) before allowing access to the data. Effective strength is about 30-40 bits.

See http://www.icao.int/mrtd/ for more technical information (assumes working knowledge of smartcard protocols and tolerance of government talk).