Why zero-knowledge proofs?
According to the recent episode on Bankless with Vitalik, he believes that one of the significant leaps in technological innovations in the blockchain and crypto industry in 2022 was zkEVMs (which are based on zero-knowledge proofs). This series of articles will go in-depth about zero-knowledge proofs, the different types and the future of this groundbreaking technology.
zkEVMs herald a better future for the blockchain and cryptocurrency industry in general. They will be the underlying rails for handling the increased traffic we will see during the next crypto bull run and possibly when the industry goes mainstream!
What are zero-knowledge proofs?
Zero-knowledge proofs (ZKPs) are a type of cryptographic method that allows one party (the prover) to prove to another party (the verifier) that they possess a certain piece of information without actually revealing that information. In other words, the prover can prove to the verifier that they know something without telling the verifier what that something is.
There are several types of zero-knowledge proofs, each with specific properties and uses. Some of the most common types are:
- Interactive proofs: These are the most basic type and involve a prover and a verifier who interact with each other to prove the prover’s knowledge.
- Non-interactive proofs: These are more complex than interactive proofs and involve a prover who creates a proof without interacting with the verifier. Non-interactive proofs are often used when the prover and verifier cannot communicate directly or when the prover wants to keep their identity private.
- Succinct non-interactive arguments of knowledge (SNARKs): These are a type of zero-knowledge proof that is particularly efficient and can be used to prove the authenticity of large amounts of data without revealing the actual data itself. SNARKs are often used in blockchain technology and other applications where it is crucial to verify the authenticity of data without revealing the data itself.
- Scalable Transparent ARgument of Knowledge (STARKs): One of the main benefits of ZK-STARKs is that they do not require a trusted setup, which means that they can be used in a wide range of applications without the need for a central authority. STARKs have been proposed as a solution for various problems, including private transactions on blockchain networks, secure multi-party computation, and more.
- Proofs of knowledge: These are a type of ZKP used to prove that a prover knows a particular secret without revealing it itself. Proofs of knowledge are often used in authentication protocols, where users must prove that they know a password or other secret to access a system.
How do zero-knowledge proofs work?
To understand how ZKPs work, it’s helpful to consider a simple example. Suppose Alice wants to prove to Bob that she knows the secret password to a certain website without actually revealing the password to Bob. Alice could use a zero-knowledge proof to accomplish this.
Here’s how it might work (in a naive implementation):
- Alice and Bob agree on a set of rules for the zero-knowledge proof. These rules might include the specific information that Alice needs to prove (in this case, that she knows the secret password) and the specific actions that Alice needs to take to prove her knowledge (for instance, logging into a website).
- Alice creates a proof that follows the agreed-upon rules. This proof might involve solving a mathematical problem or performing some other action demonstrating her knowledge of the secret password. (For example, Alice might log in to a website and make a few changes there)
- Bob verifies the proof. This involves checking that the proof follows the agreed-upon rules and accurately demonstrates Alice’s knowledge of the secret password. (For example, Bob might check the website and verify that Alice has indeed made a few changes there)
If Bob is satisfied that the proof is valid, he can conclude that Alice knows the secret password without actually learning the password itself.
What are the applications of zero-knowledge proofs?
Zero-knowledge proofs have a wide range of applications, including:
- Authentication: As mentioned earlier, ZKPs can be used to prove that a user knows a particular secret (such as a password) to access a system or service.
- Cryptocurrency transactions: They can be used to verify the authenticity of cryptocurrency transactions without revealing the details of the transaction itself. This can help protect the parties’ privacy in the transaction.
- Blockchain technology: ZKPs can be used to verify the authenticity of data stored in the blockchain without revealing the actual data itself.
- Electronic voting: They can verify the authenticity of electronic votes without revealing the specific votes themselves. This can help protect the voters’ privacy and ensure the voting process’s integrity.
- Privacy-preserving data analytics: They can be used to analyse data without revealing the data being analyzed. This can be useful when the data contains sensitive information, or the data owner wants to keep their data private.
zkEVM
Apart from the above generic applications, let’s dive deeper into one of the most exciting and impactful applications — zkEVMs. This application is bound to change the blockchain industry forever.
zkEVM (short for “Zero-Knowledge EVM”) is a novel implementation of the Ethereum Virtual Machine (EVM) that allows for the execution of smart contracts in a zero-knowledge (ZK) setting. This means that the ZK-EVM allows for the execution of smart contracts without revealing any information about the input data or the output results to anyone other than the parties involved in the transaction.
The zkEVM was first introduced in a research paper by researchers from the Ethereum Foundation and Protocol Labs in 2018. It builds upon the existing EVM architecture and uses zero-knowledge proof systems, such as zkSNARKs, to enable private and secure execution of smart contracts.
One of the main benefits of the zkEVM is that it allows for the execution of smart contracts without revealing any information about the input data or the output results. This makes it possible to execute contracts involving sensitive or confidential information, such as contracts for financial transactions or contracts for exchanging medical records.
In addition to enabling private and secure execution of smart contracts, the zkEVM also has the potential to improve scalability on the Ethereum network. Traditional EVM transactions require every node on the network to validate the transaction, which can lead to slow transaction times and high fees. On the other hand, the zkEVM allows for the validation of transactions without requiring every node on the network to participate, which can significantly reduce transaction times and fees.
Despite the potential benefits of the zkEVM, there are also some challenges and limitations to consider. One challenge is that ZKP systems, such as zkSNARKs, can be complex and difficult to implement, making it challenging for developers to use the zkEVM. In addition, using ZKP systems can also introduce additional overhead and computational costs, which may impact the scalability of the zkEVM in some instances.
What are some of the problems with Zero-knowledge proofs?
- It’s important to note that ZKPs are not a perfect solution for every situation. For example, they can be computationally intensive, making them impractical for specific applications.
- Additionally, ZKPs rely on the assumption that the prover and verifier are both honest actors and may not provide sufficient protection against malicious actors trying to deceive the verifier.
Despite these limitations, ZKPs are a powerful tool that can protect the privacy and verify the authenticity of the information in a wide range of applications. As the field of cryptography continues to evolve, we’ll see even more innovative uses for zero-knowledge proofs in the future.
In the following few articles, we will explore some real-life use cases of ZKPs in Layer 2 scaling solutions used in the Ethereum ecosystem. These applications will be game-changing for the blockchain industry and catapult it into the future!
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