By Damián Pitalúa-García.
Submitted to arXiv on 19 July 2021.
We introduce relativistic multi-party biased die rolling protocols, generalizing coin flipping to M≥2 parties and to N≥2 outcomes for any chosen outcome biases, and show them unconditionally secure. Our results prove that the most general random secure multi-party computation, where all parties receive the output and there is no secret input by any party, can be implemented with unconditional security. Our protocols extend Kent’s [A. Kent, Phys. Rev. Lett. 83, 5382 (1999)] two-party unbiased coin flipping protocol, do not require any quantum communication, are practical to implement with current technology, and to our knowledge are the first multi-party relativistic cryptographic protocols.