The quantum key distribution system using the polarisation-controlled encoder of the invention has the ability of anti-wiretapping to transmitter, receiver and quantum channel.
Provided is a biometric authentication device that can enhance usability, suppress deterioration of authentication accuracy due to ambient noise, and increase tolerance to wiretapping.
The housing would be resistant to access, tampering or tapping.
There are disclosed a transmission device and a reception device having a high secrecy making it difficult to wire tap by a third device.
It is possible to prevent wire tapping of information via a leak of an electromagnetic wave when transmitting information by using an image display device.
A fiber tap is determined to have occurred if the state of polarization of the fiber changes beyond a predetermined amount found to be associated with all types of fiber taps.
Alternately, it may be determined that a fiber tap has occurred if the state of polarization changes beyond a second predetermined amount and in a predetermined direction.