Unconditionally Secure Bit Commitment with Flying Qudits

Understand

In the task cryptographers call bit commitment, one party encrypts a prediction in a way that cannot be decrypted until they supply a key, but has only one valid key.

• Bit commitment has many applications, and has been much studied, but completely and provably secure schemes have remained elusive.
• Here we report a new development in physics-based cryptography which gives a completely new way of implementing bit commitment that is perfectly secure.
• The technique involves sending a quantum state (for instance one or more photons) at light speed in one of two or more directions, either along a secure channel or by quantum teleportation.