The information age continues to unfold in fits and starts, and the rise of blockchain is one of the most compelling current trends. It turns out that public-key cryptography, a long-stable technology, was latent with undiscovered possibilities. Blockchain is a reinvention of secure communication technology. When the histories of the internet and blockchain come together, we will be looking at a rising tide of increasingly sophisticated modes of online interaction.
Zero-knowledge proof is a key player in blockchain technology. As ZKP is better understood, unexpected use cases are discovered and new tools are developed. As a result, ZKP will likely become a component in many applications and industries. We can look to research carried out by the Mina Foundation for clues as to where ZKP is heading.
ZKP is Applied Complexity Theory
At the highest level, ZKP lets you prove you know something without divulging what you know. This has obvious privacy implications, but it’s also essential for scalability. When we use a zero-knowledge proof for an expensive computation, we can usually demonstrate the proof again without the overhead of additional computation.
In a sense, zero-knowledge proofs are a natural elaboration of trends in complexity theory and cryptography. Much of modern cryptography (of the asymmetric type) depends on complexity theory because asymmetric security relies on the use of functions that are realizable in one form but not another.
It follows that the big obstacle to understanding ZKP is mathematics. Fortunately, it is possible to conceptually understand how zero-knowledge proofs work without necessarily knowing what a quadratic residue is. For those of us who care, a quadratic residue of therefor a value z is: . This rather esoteric concept was used in one of the first zero knowledge articles. Much of cryptography relies on exploring the limits of mathematics (especially factorization and modulus) for useful properties. Encapsulating ZKP’s complex mathematical calculations into easy-to-use libraries will be key to widespread adoption.
We can do a myriad of interesting things with such one-way functions. In particular, we can establish shared secrets over open networks, a capability on which modern secure communications rely. Zero knowledge asks the question: can we use similar kinds of smart calculations to prove something while keeping the information hidden? The answer is yes.
ZKP apps and protocols
Current practical zero-knowledge proofs are built on the demonstration that a given computation has taken place. Protocols like ZK-SNARK and ZK-STARK are two prominent examples that package this evidence into a digestible format. Once you have ZKP abilities, you can assert that something is true and others can accept it with a high degree of probability. ZKP is a form of probabilistic proof.
Such proofs involve complexity, which adds to the challenge of ensuring that they are resistant to attack. Progress in the field is therefore slow. However, zero-knowledge proofs continue to grow in power and today are able to demonstrate many claims in a relatively compact format. The broadening of the types of things that can be proven and the variety of systems in which they can fit are key research areas. Another area is to make deployment as simple as possible.
ZKP and the future of blockchain
The Mina Foundation has do some interesting research on the importance of ZKP in the blockchain industry. This research asked blockchain users and developers about ZKP in their industry. Privacy and performance were the two main drivers for ZKP adoption.
Just over 30% of respondents identified privacy as the most important use case for ZKP. Whenever an exchange between parties requires proving something to be true and a zero-knowledge proof can be devised to do so, confidentiality increases. It is not easy or easy since the proofs themselves and their integration with communication protocols are difficult. Nevertheless, privacy is an important driver for ZKP. There may come a day when critical proofs, such as proving one’s citizenship, will be done through ZKP.
Evan Shapiro, CEO and Founder of the Mina Foundation, highlighted privacy when he told me “we’ve seen a lot of ZK for scalability improvements, especially for Ethereum, but ZK’s programmable privacy apps will become a dominant goal for developers in 2023,” adding that he is “particularly excited about zkIdentity, and the potential for DeFi applications to use ZK to enable KYC [know your customer] compliance process without collecting or storing sensitive user data. »
More generally, ZKP can enable more secure systems that expose less information in their activities, which means less chance of the information being exploited for nefarious purposes. An interesting finding from the research is that financial information is at the forefront of the data users hope to keep private with ZKP (54.5%). This may not be surprising, but consider it alongside the discovery of who users want to maintain privacy of. Governments come first with 48.5%.
The passion to keep financial information out of sight of the government has not gone unnoticed by tax officials. At the same time, preferring to disclose little to centralized government while paying legitimate taxes is the perfectly legitimate right of free citizenship. ZKP systems could allow this type of tax system. Proving what you owe without disclosing anything else could be a zero-knowledge use case.
Another key area is performance optimization, which 18.2% of respondents named ZKP’s most important feature. ZKP can prove that a calculation is valid in a small and compact form and therefore reduce the number of times such a calculation needs to be performed. The MINA blockchain uses this feature to summarize transactions on the blockchain, which improves performance and ultimately equates to a lower cost system. Transactional throughput and fee reduction are often seen as critical factors in the long-term viability of blockchain.
When asked about ZKP’s most important application, 46% of Mina survey respondents said both privacy and scalability mattered. In short, the future of blockchain will likely involve ZKP’s contribution to creating more secure and better performing systems.
Zero-knowledge proof is at the frontier of cryptographic research. It promises to improve both the scalability and security of cryptosystems. These improvements have big implications for the future of blockchain and, by extension, the wider world of distributed computing.
There’s a lot of work to be done to uncover and apply the promise of the zero-knowledge proof, and that work is well underway. It’s a safe bet that ZKP will have a significant impact on information technology in the coming years.
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