Cryptology ePrint Archive: Report 2016/039

Standard quantum bit commitment an indefinite commitment time

Muhammad Nadeem

Abstract: Currently, it is believed in the literature that unconditionally secure bit commitment is impossible in non-relativistic quantum cryptography while only a weaker notion of bit commitment with finite commitment time is achievable in relativistic quantum setting. Moreover, relativistic classical bit commitment protocols allow arbitrary long commitment time but such protocols are not practically feasible; either because of multiple rounds of communication that result in exponential increase in communication complexity or due to asymptotic nature of security argument. The impossibility of practically feasible standard bit commitment leaves an obvious skepticism on the completeness of Hilbert space quantum cryptography and its claims of unconditional security. Contrary to the previously proposed results, we demonstrate here that an information-theoretic standard bit commitment scheme can be devised by using rules of purely non-relativistic quantum mechanics only; neither additional resources from theory of relativity nor multiple rounds of communications are required. The proposed bit commitment scheme can be applied efficiently with existing quantum technologies without long term quantum memory; quantum entanglement is required only for time t+&#948; where t is the communication time between the committer and receiver while &#948; << t is the processing time at laboratory.

Category / Keywords: foundations / bit commitment

Date: received 14 Jan 2016

Contact author: muhammad nadeem at seecs edu pk

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Version: 20160117:173415 (All versions of this report)

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