How Bitcoin Prevents Double Spending Without a Central Authority

Table of Links

II. Background

A. Bitcoin Basics

B. Bitcoin Security

C. Grover’s Search Algorithm

D. Quantum Attacks

III. Approach

A. Algorithm

B. Markov Chain

C. Assumptions and Approximations

IV. Results

A. Probability of Success

B. Performance Measures

C. Example Application

V. Discussion, Acknowledgments, and References

B. Bitcoin Security

The central problem all digital currencies must overcome is double spending attacks, in which currency is spent twice by the same entity. To overcome this problem, protocols can use a central authority that verifies, before every transaction, that the currency involved has not already been spent. The Bitcoin network has no such central authority and instead relies on the blockchain. The blockchain provides a public ledger which can be used to check against double spending.

Authors:

(1) Robert R. Nerem, Institute for Quantum Science and Technology, University of Calgary, Alberta T2N 1N4, Canada ([email protected]);

(2) Daya R. Gaur, Department of Mathematics and Computer Science, University of Lethbridge, Alberta T1K 3M4, Canada.

This paper is available on arxiv under CC BY 4.0 DEED license.