zk-SNARK Technology In A Nutshell

zk-SNARK technology is cryptographic proof allowing one party to prove it possesses information without having to reveal it. zk-SNARK is an acronym for Zero-Knowledge Succinct Non-Interactive Argument of Knowledge. More specifically, a zk-SNARK is a zero-knowledge proof protocol used to prove possession of certain information without revealing that information. This technology might play a key role in the future development of Ethereum.

Aspect	Explanation
Definition	zk-SNARK (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge) is a cryptographic technology that allows one party (the prover) to prove to another party (the verifier) that they possess certain information, such as a secret key or the solution to a mathematical problem, without revealing the actual information itself. This proof is succinct, meaning it’s short and requires minimal computational resources, and non-interactive, meaning it doesn’t involve back-and-forth communication between the prover and verifier. zk-SNARKs are widely used for enhancing privacy and security in blockchain and cryptographic applications.
Key Concepts	– Zero-Knowledge Proof: zk-SNARKs are a type of zero-knowledge proof, meaning they allow one party to prove knowledge of something without revealing the knowledge itself. – Succinctness: zk-SNARKs provide a concise and efficient way to create proofs, making them suitable for resource-constrained environments like blockchains. – Non-Interactivity: The proof can be generated and verified without the need for multiple rounds of interaction. – Public Parameters: zk-SNARKs rely on a set of public parameters generated during setup, which are used for proving and verifying. – Security Assumptions: The security of zk-SNARKs is based on certain cryptographic assumptions, such as the hardness of specific mathematical problems.
Characteristics	– Privacy: zk-SNARKs enable privacy-preserving transactions and computations, as they reveal nothing about the actual data or knowledge being proved. – Efficiency: They provide a highly efficient way to create and verify proofs, making them suitable for real-time applications. – Scalability: zk-SNARKs can significantly reduce the computational load of blockchain networks by offloading certain verifications. – Cryptographic Foundations: They rely on advanced cryptographic techniques like elliptic curve pairings and hash functions. – Use in Blockchains: zk-SNARKs are used in various blockchains for improving privacy and reducing transaction costs.
Implications	– Privacy on Blockchains: zk-SNARKs enable confidential transactions on public blockchains, hiding transaction amounts and sender/receiver information. – Scalability: They can help in scaling blockchain networks by reducing the computational overhead of verifying transactions. – Reduced Data Exposure: In various applications, zk-SNARKs allow users to prove specific knowledge without revealing sensitive data, enhancing security. – Efficient Verification: Verifying zk-SNARK proofs is computationally efficient, which is crucial for real-time applications. – Secure Multiparty Computation: zk-SNARKs are used in secure multiparty computation protocols for collaborative data analysis without revealing the data itself.
Advantages	– Privacy: zk-SNARKs provide strong privacy guarantees by ensuring that only the necessary information is revealed. – Efficiency: They enable efficient transaction verification, reducing the computational load on blockchain networks. – Scalability: zk-SNARKs can contribute to the scalability of blockchain platforms. – Security: They are based on established cryptographic principles and have undergone extensive scrutiny for security. – Cross-Chain Compatibility: zk-SNARKs can be implemented in various blockchains, enhancing interoperability.
Drawbacks	– Setup Complexity: The initial setup of zk-SNARK parameters can be complex and requires trust in the setup process. – Mathematical Assumptions: Security relies on specific mathematical assumptions that, if broken, could compromise the technology. – Limited Adoption: While gaining traction, zk-SNARK adoption is not yet widespread across all blockchain platforms. – Resource Intensive: Creating zk-SNARK proofs can still be resource-intensive for some applications. – Regulatory Considerations: The privacy features of zk-SNARKs may raise regulatory concerns in certain jurisdictions.
Applications	zk-SNARK technology finds applications in various fields, including blockchain, cryptography, and privacy-enhancing technologies.
Use Cases	– Privacy Coins: Cryptocurrencies like Zcash use zk-SNARKs to enable private transactions. – Blockchain Scalability: zk-SNARKs are employed to improve the scalability of blockchains like Ethereum. – Secure Messaging: They can be used for secure end-to-end encrypted messaging without revealing message contents. – Voting Systems: zk-SNARKs enhance the security and privacy of electronic voting systems. – Supply Chain: They are used to prove the authenticity of products in supply chain tracking. – Identity Verification: zk-SNARKs enable proving identity without revealing personal information. – Data Sharing: In healthcare and finance, zk-SNARKs allow data sharing for analysis without exposing sensitive information.

Table of Contents

Understanding zk-SNARK technology

The first zero-knowledge proofs were developed in the late 1980s, with a seminal research paper entitled How to Explain Zero-Knowledge Protocols to Your Children released in 1990 by cryptographer Jean-Jacques Quisquater.

The paper explains zero-knowledge proofs in the context of a parable involving Ali Baba’s Cave. But for the sake of brevity, it’s important to understand that these proofs have one fundamental goal and three key players. The verifier must convince themselves that the prover possesses knowledge of a secret parameter called a witness. This witness must satisfy some relation without it being revealed to the verifier or indeed anyone else.

In a real-world scenario, imagine a patron wanting to enter a bar and having to prove they were over the legal drinking age of 21. The patron does not want to reveal their exact age, but the bouncer at the door must verify whether they are legally allowed to drink. Theoretically, the bouncer could use zero-knowledge proofs to scan the patron’s ID and determine whether they were over 21. Note that the exact age of the patron does not need to be revealed.

Today, zk-SNARK is commonly associated with cryptocurrency and blockchain. We will take a look at this association in the next section.

zk-SNARK technology and cryptocurrency

When cryptocurrencies such as Bitcoin were first developed, privacy was less important than a need to create a trust-less system for maintaining the integrity of digital transactions.

Indeed, Bitcoin users assumed such transactions were anonymous because their real identities were not associated with user public keys. In recent years, concerted attempts by data scientists, hackers, and law enforcement proved it was relatively simple to identify people who had given pseudonymous information to multiple sources.

This put the spotlight back on privacy and lead to the development of coins such as Zcash that were backed by zk-SNARK technology. This technology is based on complex mathematical functions, but in the case of Zcash, zk-SNARKS can be verified nearly instantly without any interaction between the prover and the verifier. The identity of the prover and verifier are kept hidden, as is the payment amount. Importantly, zk-SNARKS usually take up much less data than a standard Bitcoin transaction and are more scalable as a result.

Future applications of zk-SNARKs

zk-SNARK has virtually limitless future applications because it is useful wherever verification is required without disclosing inputs or leaking information.

Having said that, its usefulness is somewhat limited since the generation of proofs for complex functions is resource-intensive. In cryptocurrency, the makers behind Zcash are working to optimize this process to make it more widely available.

In any case, zk-SNARKs can be added to any existing distributed ledger solution to add an extra layer of security for enterprise use cases. This solution is particularly attractive for multiple companies operating on the same blockchain with a desire to keep sensitive or proprietary business information private. Instead of revealing this information to other players, zk-SNARKS allow each business to store only the proof of each transaction on a given node.

Key takeaways:

zk-SNARK technology is cryptographic proof allowing one party to prove it possesses information without having to reveal it.
zk-SNARK technology is most commonly associated with blockchain and cryptocurrency, but it was coined as far back as the late 1980s by cryptographer Jean-Jacques Quisquater.
zk-SNARK technology is a vital tool for multiple businesses operating on the same blockchain with sensitive information. The technology will become much more widespread once verification functions become less computationally intensive.