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In this work, we present a novel T-PAKE protocol which solves the above fault management problem by employing a batched and offline phase of distributed key generation (DKG). Our protocol is secure against any malicious behavior from up to any t < n servers under the decisional Diffie-Hellman assumption in the random oracle model, and it ensures protocol completion for t < n/2. Moreover, it is efficient (16n + 7 exponentiations per client, 20n + 14 per server), performs explicit authentication in three communication rounds, and requires a significantly lesser number of broadcast rounds compared to previous secure T-PAKE constructions. We have implemented our protocol, and have verified its efficiency using micro-benchmark experiments. Our experimental results show that the protocol only introduces a computation overhead of few milliseconds at both the client and the server ends, and it is practical for use in real-life authentication scenarios.
To this end, we first formalize the requirements of ZKPPC protocols and propose a general framework for their construction in the standard model using randomised password hashing and set membership proofs. We design a suitable encoding scheme for password characters and show how to express password policies to allow the adoption of set membership proofs. Finally, we present a concrete ZKPPC-based registration protocol that is based on efficient Pedersen commitments and corresponding proofs, and analyse its performance.
To complete the ZKPPC-based registration and authentication framework we propose a concrete VPAKE protocol, where the server can use the obtained verification information from the ZKPPC-based registration phase to subsequently setup secure communication sessions with the client. Our VPAKE protocol follows the recent framework for the construction of such protocols and is secure in the standard model.
We construct the first fuzzy extractors that work for a large class of distributions that have negative minimum usable entropy. Their security is computational. They correct Hamming errors over a large alphabet. In order to avoid the worst-case loss, they necessarily restrict distributions for which they work.
Our first construction requires high individual entropy of a constant fraction of symbols, but permits symbols to be dependent. Our second construction requires a constant fraction of symbols to have a constant amount of entropy conditioned on prior symbols. The constructions can be implemented efficiently based on number-theoretic assumptions or assumptions on cryptographic hash functions.
The basic idea is to excise the bitcoin money generation formula, and otherwise apply bitcoin essentially \"as is\" over digital coins which are redeemable by the mint that minted them. This will preserve the bitcoin assured anonymity. The new bitcoin.BitMint solution will benefit from bitcoin\'s double-spending prevention, and would otherwise enjoy all the benefits associated with money in a digital form.
bitcoin.BitMint will allow traders to invest in US$, gold, or any other commodity while practicing their trade in cyberspace, anonymously, securely, and non-speculatively.
This \"mint-in-the-middle\" protocol will allow law enforcement authorities to execute a proper court order to enforce the disclosure of a suspected fraudster, but the community of honest traders will trade with robust privacy as offered by the original bitcoin protocol.
We envision interlinked bitcoin.BitMint trading environments, integrated via an InterMint protocol: a framework for the evolution of a cascaded super currency - global and highly stable.