Variance: Secure Two-Party Protocol for Solving Yao\u27s Millionaires\u27 Problem in Bitcoin

Secure multiparty protocols are useful tools for parties wishing to jointly compute a function while keeping their input data secret. The millionaires’ problem is the first secure two-party computation problem, where the goal is to securely compare two private numbers without a trusted third-party. There have been several solutions to the problem, including Yao’s protocol [Yao, 1982] and Mix and Match [Jakobsson and Juels, 2000]. However, Yao’s Protocol is not secure in the malicious model and Mix and Match unnecessarily releases theoretically breakable encryptions of information about the data that is not needed for the comparison. In addition, neither protocol has any verification of the validity of the inputs before they are used. In this thesis, we introduce Variance, a privacy-preserving two-party protocol for solving the Yao’s millionaires’ problem in a Bitcoin setting, in which each party controls several Bitcoin accounts (public Bitcoin addresses) and they want to find out who owns more bitcoins without revealing (1) how many accounts they own and the balance of each account, (2) the addresses associated with their accounts, and (3) their total wealth of bitcoins while assuring the other party that they are not claiming more bitcoin than they possess. We utilize commitments, encryptions, zero knowledge proofs, and homomorphisms as the major computational tools to provide a solution to the problem, and subsequently prove that the solution is secure against active adversaries in the malicious model

Quantum Computing, how it is jeopardizing RSA, and Post-Quantum Cryptography

Quantum computers are a fact and with the quantum computers follows quantum algorithms. How will quantum computing affect how we look at public-key cryptography? And more specifically: how will it affect the most widely used public-key algorithm RSA? The impact of quantum computing is unimaginable and it will affect a massive amount of applications like e-commerce, social networks, mobile phones, generally our day to day life. A solution has been presented: Post-Quantum Cryptography. Even though Post-Quantum primitives have been suggested, there is not yet any algorithms that has been chosen to replace our current public-key standards. A standardizing process was started in 2016 by NIST and is still ongoing.Masteroppgave i informatikkINF399MAMN-INFMAMN-PRO