Zero Knowledge Proofs and the Future of Authentication

Authentication is essential when it comes to the security and privacy of online transactions and communications. It is the process of verifying the identity of a user or a system before granting it access. Currently, most methods used in authentication rely on sharing or storing sensitive information, such as passwords, PINs, biometric data, or cryptographic keys. But sometimes these methods are vulnerable to various attacks and data breaches that often compromise the user’s privacy by revealing more information than necessary for authentication.

This is where Zero-knowledge proofs (ZKPs) come in. ZKPs is a technique that allows one party to convince another party of the validity of a statement without revealing any information beyond the statement itself. In this article, we will examine the application of ZKPs in authentication and their potential to revolutionize online security.

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Let’s gooooo 🚀

Content Overview

• 🛫🛬Time Travel: Traditional Authentication Methods
• What are Zero-knowledge Proofs?🧐
• Cryptographic techniques
• Applying Zero-knowledge Proofs to Authentication⚔⛓
• Potential Implications for Online Security
• Challenges and Considerations
• Conclusion
• References

🛫🛬Time Travel: Traditional Authentication Methods

Before we dive into ZKPs and what it’s all about let’s look at some traditional methods of Authentication.

Passwords

The most common traditional authentication method is passwords. A password is a secret string of characters that the user chooses, and the password is entered when logging in to a system or a service. The system or the service verifies the password by comparing it with a stored copy of the password and then grants access to the user if it is correct.

Passwords are easy to implement and use, but they have several drawbacks, some of which are:

• Passwords are often weak and easy to guess or crack by attackers.
• They are vulnerable to phishing, where attackers trick users into revealing their passwords through fake websites or emails.
• They are susceptible to replay attacks, where attackers intercept and reuse the passwords to access the system or the service.
• Passwords are inconvenient for users, who have to remember and manage multiple passwords for different accounts.

Two-Factor Authentication

Another authentication method is the use of two-factor authentication (2FA). 2FA is a technique that requires the user to provide two pieces of evidence to prove their identity. The two pieces of evidence are usually something the user knows such as a password or a PIN and something the user has such as a token. 2FA is more secure than passwords alone, as it adds an extra layer of protection against phishing, replay, and brute force attacks.

However, 2FA also has some limitations which are:

• 2FA depends on the availability and security of the second piece of evidence, which can be lost, stolen, or compromised.

• It can be inconvenient for users, who have to carry and use the second piece of evidence every time they log in.

• 2FA can still reveal more information than necessary for authentication, such as the user’s phone number, email address, or device identifier.

  
  

As we can note these traditional authentication methods are great but they all have huge individual drawbacks. That is what led us to Zero-Knowledge Proofs (ZKPs)

What are Zero-knowledge Proofs?🧐

Zero-knowledge proofs are a cryptographic technique that allows one party (the prover) to convince another party (the verifier) of the validity of a statement without revealing any information beyond the statement itself. For instance, the prover can prove to the verifier that they know the password to a system without revealing the password itself, the prover can also prove to the verifier that they have a certain attribute or credential without disclosing the attribute or credential itself. For example, the prover can prove to the verifier that they are over 18 years old without revealing their date of birth.

Basic principles of Zero-knowledge proofs

There are certain principles of ZKPs, which are:

• Completeness: If the statement is true and the prover is honest, the verifier will always accept the proof.
• Soundness: If the statement is false and the prover is dishonest, the verifier will reject the proof with high probability.
• Zero-knowledge: The verifier learns nothing from the proof except the validity of the statement.

Key components of zero-knowledge proofs

• A statement: The statement is a claim that the prover wants to prove to the verifier. It can be expressed as a mathematical equation or a logical formula.
• A witness: The witness is a piece of information that the prover knows and the verifier does not. The witness is used to construct the proof and is kept secret from the verifier. It can be a password, a key, a credential, or any other secret data.
• A protocol: The protocol is a series of steps or interactions between the prover and the verifier. It involves the prover sending messages to the verifier and the verifier sending challenges to the prover. The protocol is designed to ensure the completeness, soundness, and ZK properties of the proof.

Cryptographic techniques

The cryptographic techniques involved in Zero-knowledge proofs are:

1. Hash functions

   Hash functions are mathematical functions that map any input to a fixed-length output. Hash functions are one-way, meaning that it is easy to compute the output from the input, but hard to compute the input from the output. Hash functions are also collision-resistant, meaning that it is hard to find two different inputs that produce the same output. Hash functions are used to hide or commit to the witness or the message in the protocol.

   
   

2. Encryption schemes

   Encryption schemes are methods of transforming data into an unreadable form using a key. Encryption schemes are either symmetric or asymmetric. Symmetric encryption schemes use the same key for encryption and decryption. Asymmetric encryption schemes use different keys for encryption and decryption. The encryption key is public and can be shared, while the decryption key is private and kept secret. Encryption schemes are used to encrypt or decrypt the witness or the message in the protocol.

   
   

3. Digital signatures

   Digital signatures are methods of verifying the authenticity and integrity of a message using a key pair. The sender signs the message using their private key, and the receiver verifies the signature using the sender’s public key. Digital signatures are used to sign or verify the witness or the message in the protocol.

   
   

Zero-knowledge proofs have been implemented in various fields, such as blockchain, cryptography, and privacy. ZKP has been implemented in apps and systems such as Zcash, Signal, Idemix, etc.

Applying Zero-knowledge Proofs to Authentication⚔⛓

Zero-knowledge proofs can be applied to authentication systems to enhance their security, privacy, and user-friendliness. It can enable authentication processes that do not follow the traditional authentication processes. Instead, the user can prove their identity or their possession of a credential using a Zero-knowledge proof protocol.

The concept of “zero-knowledge” in user verification means that the user only reveals the minimum amount of information necessary to prove their identity or their credentials, and nothing more.

Some examples of successful ZKP-based authentication systems are:

Secure Quick Reliable Login(SQRL)

This is a system that uses Zero-knowledge proofs to enable passwordless authentication. SQRL allows users to create a single master key that is derived from a passphrase and stored on their device. The user can use the master key to generate a unique public-private key pair for each website or service they want to log in to. The user can then use the private key to sign a challenge from the website or service and use the public key to verify the signature. The website or service can use the public key as the user’s identifier, without requiring the user to create or remember a password.

Fast Identity Online(FIDO)

FIDO is a set of standards that use Zero-knowledge proofs to enable secure and convenient authentication. It supports two types of authentication: passwordless and second-factor.

• Passwordless authentication: It allows users to log in to a website or service using a device that has a built-in or attached authenticator, such as a fingerprint scanner, a facial recognition camera, or a security key. The user can use the authenticator to generate a public-private key pair for each website or service they want to log in to. The user can then use the private key to sign a challenge from the website or service and use the public key to verify the signature. The website or service can use the public key as the user’s identifier, without requiring the user to create or remember a password.

  
  

• Second-factor authentication: This allows users to add an extra layer of protection to their existing password-based authentication. The user can use the same authenticator to generate a one-time code or a response to a challenge from the website or service and use the public key to verify the signature. The website or service can use the public key as a second factor of authentication, in addition to the user’s password.

Advantages of Zero-knowledge Proofs in Authentication

Zero-knowledge proofs offer several advantages over traditional authentication methods in terms of security, privacy, and user-friendliness.

• ZKPs mitigate common security risks associated with authentication, such as phishing, replay, brute force, man-in-the-middle, or data breaches.
• They do not require the user to share or store any sensitive information, such as passwords, PINs, biometric data, or cryptographic keys. Therefore, there is nothing for the attackers to steal, intercept, or reuse.
• It also ensures that the user is in possession of the secret or the credential at the time of authentication, and not just a copy or a replica. This prevents the attackers from impersonating the user or forging the proof.
• ZKPs protect the user’s privacy and prevent the leakage or misuse of their personal data.
• It only reveals the minimum amount of information necessary to prove the user’s identity or credentials, and nothing more. For example, the user can prove that they are over 18 years old without revealing their date of birth, or that they have a valid driver’s license without revealing their name or address..
• ZKPs also prevent the correlation or tracking of the user’s activities across different websites or services, as the user can use different public keys or identifiers for each website or service.
• They enable a seamless and convenient authentication experience for the user.
• They do not require the user to create or remember multiple passwords for different accounts or to carry and use a second piece of evidence for 2FA. Instead, the user can use a single device or authenticator that has a built-in or attached Zero-knowledge proof protocol. The user can then use the device or the authenticator to log in to any website or service that supports Zero-knowledge proof authentication, without entering any password or code.
• ZKPs also reduce the authentication time and latency, as the proof can be generated and verified in a few milliseconds.

Potential Implications for Online Security

Zero-knowledge proofs have the potential to transform the online security landscape by reducing the incidence and impact of data breaches and identity theft, and by increasing the user’s trust and confidence in the authentication systems.

• Impact on data breaches and identity theft: Data breaches and identity theft are major threats to online security, as they expose the user’s personal and financial data to unauthorized access and misuse.

  
  

  In a report by Risk Based Security, there were 3,932 publicly reported data breaches in 2020, exposing over 37 billion records. According to a report by Javelin Strategy & Research, there were 49 million victims of identity fraud in 2020, resulting in $56 billion in losses.

  
  

  Zero-knowledge proofs can significantly reduce the risk and damage of data breaches and identity theft. They eliminate the need for storing or sharing any sensitive information for authentication. Therefore, there is nothing for the attackers to steal or exploit from the databases or the networks of the websites or services. Even if a data breach occurs, the attackers cannot use the public keys or the identifiers to access the user’s accounts or impersonate the user, as they do not have the corresponding private keys or secrets.

  
  

• Potential reduction in account takeovers and unauthorized access: Account takeovers and unauthorized access are another threat to online security, as they allow attackers to access the user’s accounts or resources without their consent or knowledge.

  
  

  According to a report by Arkose Labs, there were 1.1 billion fraudulent login attempts in the first quarter of 2020, accounting for 26.5% of all login attempts. In another report by NuData Security, there were 7.7 billion account takeover attempts in 2020, representing a 650% increase from 2019.

  
  

  ZKPs can also reduce the likelihood and impact of account takeovers and unauthorized access, as they require the user to prove their possession of the secret or the credential at the time of authentication, and not just a copy or a replica. Therefore, the attackers cannot use the stolen or intercepted passwords, codes, or keys to access the user’s accounts or resources, as they do not have the actual secret or the credentials.

  
  

• Addressing concerns related to user trust and system reliability: User trust and system reliability are essential for the adoption and success of any authentication system. However, many users are concerned about the security and privacy of their personal data and credentials, and the reliability and availability of the authentication systems.

  
  

  In a survey by IBM Security, 75% of users are concerned about the security of their biometric data, and 55% of users are concerned about the privacy of their biometric data. In another survey by Ping Identity, 81% of users would stop engaging with a brand online after a data breach, and 63% of users would switch to a competitor that offers a better user experience.

  Zero-knowledge proofs can address these concerns by providing a secure, private, and user-friendly authentication system. ZKPs do not require the user to share or store any biometric data or other sensitive information and do not reveal any information beyond the validity of the proof. Zero-knowledge proofs also do not depend on the availability or security of a third party or a central authority and can operate in a decentralized or distributed manner.

Challenges and Considerations

While Zero-knowledge proofs offer many benefits for authentication, they also pose some challenges and considerations that need to be addressed before they can be widely adopted and implemented.

1. Technical challenges: ZKPs are complex and computationally intensive cryptographic techniques that require advanced mathematical and programming skills to design and implement. They also require a high level of coordination and standardization among the different parties involved in the authentication process, such as the users, the websites, the services, the issuers, and the verifiers.

   
   

2. User acceptance and education: Zero-knowledge proofs are a new and unfamiliar authentication paradigm that may require a significant shift in the user’s behavior and expectations. Users may not understand how ZKPs work, or why they are more secure and private than traditional authentication methods. Users may also be reluctant to trust or use a system that does not require them to share or store any information, or that does not provide them with any feedback or confirmation during the authentication process. Therefore, users need to be educated and informed about the benefits and risks of Zero-knowledge proofs, and how to use them properly and safely.

   
   

3. Ethical considerations and the responsible use of Zero-knowledge proofs: Zero-knowledge proofs are a powerful and versatile cryptographic technique that can be used for various purposes and applications, not only for authentication. However, ZKPz can also be misused or abused by malicious actors or entities, such as criminals, terrorists, hackers, or governments, to hide or conceal their activities, identities, or intentions. For example, ZKPs can be used to facilitate money laundering, tax evasion, illegal transactions, or cyberattacks, without leaving any trace or evidence.

Conclusion

Zero-knowledge proofs have the potential to transform the cybersecurity landscape by enhancing the security, privacy, and user-friendliness of online transactions and communications. Zero-knowledge proofs can also enable new and innovative applications and services that were not possible or feasible before.

However, Zero-knowledge proofs also pose some challenges and considerations that need to be addressed and resolved before they can be widely adopted and implemented. Therefore, Zero-knowledge proofs require continued research and development, as well as user education and awareness, to realize their full potential and impact.

References

• IBM Report: Consumers Pay the Price as Data Breach Costs Reach All-Time High
• A Detailed Explanation of Zero-Knowledge Proofs (ZKP) (gate.io)
• What is a Zero-Knowledge Proof? ZKPs Explained [2023] (thirdweb.com)
• The Complete Full-Stack Guide to Getting Started with Zero-Knowledge Proofs using Circom and ZK-Snarks - Part 1 - DEV Community
• 81% of Consumers Would Stop Engaging with a Brand Online After a Data Breach, Reports Ping Identity
• Fraud Won't Return to Pre-Pandemic Levels: Q1 Fraud Report | Arkose Labs
• The Architecture of an Attack: NuData Breaks Down Account Takeover Attacks - PaymentsJournal
• Data breaches in the first half of 2021 exposed 18.8 billion records | 2021-08-04 | Security Magazine
• 2021 Identity Fraud Study: Shifting Angles | Javelin (javelinstrategy.com)