Zero Knowledge Proofs

27 Jul 2016

Zero Knowledge Protocols without magic

In this post, we talk about Zero-Knowledge Proofs, tie ZKP authentication to traditional security models and help you understand better how authentication, in general, should work. 

Themis cryptography Secure Comparator zkp

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11 Feb 2016

Fixing Secure Comparator

After publishing Secure Comparator paper, we've received a number of concerns from the cryptographic community about possible security breach, in case, where one of the parties is intentionally falsifying the protocol. We've adressed these concerns, and, in this blog post and paper update would like to elaborate how and why. 

Themis cryptography Secure Comparator zkp

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9 Dec 2015

Introducing Secure Comparator

Secure Comparator is a novel authentication technique we're proposing the cryptographic community to evaluate. It can be used as any id/secret pair authenticator in environments, where no trust relationships exist between two parties.

Themis cryptography Secure Comparator zkp

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26 Nov 2015

Why we need novel authentication schemes?

Current technological advancements in authenticating users seems to be sufficient for most cases. However, taking a more detailed look reveals weaknesses and tradeoffs in all existing authentication schemes. Before explaining the methodology and cryptography behind Secure Comparator, our authentication protocol, we wanted to outline reasons for developing it in a brief review of existing authentication methods.

applied security cryptography Web Secure Comparator zkp

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18 Nov 2015

Armoring ed25519 to meet extended security challenges

When developing new, advanced features of Themis library, we had to extend some of the ECC cryptography available in open source with our own implementation to provide simple point multiplication with random (unknown in advance) point. To achieve that, we've extended Daniel J. Bernstein's implementation of ed25519 with our own math and code. This blog post outlines our direction of thinking.

Themis cryptography Secure Comparator zkp

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Cossack Labs is a privately-held British company with a team of data security experts based in Kyiv, Ukraine.