Web engineers have been working for a long time to determine if there is a way to prove something is true without revealing any data that substantiates the claim. Zero-knowledge proof (ZKP) technology has enabled the deployment of cryptographic algorithms for verifying the veracity of claims regarding the possession of data without unraveling it. These proof mechanisms have led to advanced mechanisms that enhance privacy and security.

Leveraging blockchain deals with problems related to centralization, while the lack of privacy in decentralized applications (DApps) can be balanced with cryptographic ZKP algorithms.

This article provides a primer on zero-knowledge proofs, portable identity, problems in prevailing identity solutions, blockchain-based zero-knowledge proof powered portable identity solutions, trustless authentication and the process of creating password credentials.

What is a zero-knowledge proof?

A zero-knowledge proof is a cryptographic technique that establishes the authenticity of a specific claim. It enables a protocol to demonstrate to a verifier that a claim about certain confidential information is accurate without disclosing any critical information. The technology facilitates interactive as well as non-interactive zero-knowledge-proof applications. 

An interactive proof needs multiple communication mechanisms between the two parties. On the other hand, a non-interactive zero-knowledge proof requires a single exchange of information between participants (prover and verifier). It improves zero-knowledge efficiency by reducing the back-and-forth communication between the prover and the verifier.

A zero-knowledge proof works by a prover showcasing to a verifier that they have an identifying secret without disclosing the secret itself. For instance, a prover might be holding an asymmetric key pair and using the identifying secret as a private key to respond to the statement sent with the public key. This culminates in a situation where the verifier is convinced that the prover has the key without the prover revealing it.

Thanks to zero-knowledge proof technology, a user could demonstrate they are of an appropriate age to get access to a product or service without revealing their age. Or someone could prove they have sufficient income to fulfill criteria without having to share precise information about their bank balance.

Zero-knowledge identity authentication

The need of businesses to manage voluminous amounts of consumer data while ensuring consumers' privacy and complex regulatory compliance led to a burgeoning need for innovative digital identity solutions. Zero-knowledge proof has helped fructify the concept of a portable digital identity efficiently.

Identity portability refers to the ability of users to generate a single set of digital ID credentials usable across multiple platforms. A digital identity management scheme clubs unique identifiers on a user’s device, relevant legal documents and biometrics such as face ID or fingerprints. 

Understanding how a decentralized identity (DID) wallet is stored on a smartphone will help you get a better grasp. An issuer attaches a public key to verifiable credentials they have issued. Securely held in the wallet, the credentials are passed on to the verifiers. All a verifier needs to do is confirm that the proper issuer cryptographically signed a credential sent by a user.

Problems in prevalent identity solutions

Hard-hitting data breaches, privacy overreach and abysmal authentication have been the nemesis of online applications. This is drastically different from the time of initial web architecture when user identity wasn't a priority. 

Traditional authentication methods no longer suffice due to our complex and ever-changing security environment. These methods severely restrict users' control over their identities and risk management, thus compromising access to essential data. Usually, enterprises use different identity services to resolve various identity-related issues.

Stemming data from diverse sources through a string of advanced technologies has made preserving identity-related data a cumbersome task. Gathering multidimensional data while adhering to a vast set of regulations has made it exceedingly complex for businesses to resolve identity-related issues quickly, detect fraud and uncover business opportunities simultaneously.

Zero-knowledge-powered-portable identity solutions

Cross-channel, portable self-sovereign identity solutions enable enterprises to secure customer access and data using a single platform. Such a seamless identity experience reduces the churn of customers. Effortless, secure workstation login helps secure remote work and reduces fraud risks associated with weak passwords.

A blockchain-based solution stores identity within a decentralized ecosystem, enabling one to prove identity when necessary. NuID, for instance, leverages a zero-knowledge proof protocol and distributed ledger technologies to facilitate digital identification for individuals and businesses.

NuID’s ecosystem allows users to own and control their digital identity by using services built upon foundational zero-knowledge authentication solutions. The decentralized nature of the solution results in an inherently portable and user-owned identity platform. They can own, control, manage and permit the usage of identity-related data efficiently.

The solution makes business enterprises “consumers” of these identities and their associated metadata, thus promoting more privacy-centric interactions. Dynamic data ownership benefits both the user and the service provider. It eliminates the need for companies to secure a humongous amount of user data, as they no longer need to hide any sensitive, identifying information.

Trustless authentication

When building a software application, authentication is one of the primary steps. In a rapidly evolving security landscape, where context-specific UX (user experience) needs are steadily expanding, user privacy concerns require more than conventional authentication. Applications require a platform that facilitates adaptation to changing demands of digital identification.

Trustless authentication provides a robust alternative to the model of storing passwords in private databases. NuID Auth API (Application Programming Interface), for instance, rolls out endpoints for creating and verifying user credentials through ZKP technology, facilitating the generation of proofs and credentials in client applications for use cases like user registration and user login.

One can expect an advanced platform to address common authentication and user management pitfalls. Features could include password blacklisting to securely inform users of weak and stolen credentials, modular and accessible authentication UI components, and advanced MFA (multi-factor authentication) functionality.

The process of creating password credentials

The process is somewhat similar to the existing workflow for creating and verifying passwords. One takes user info (name, email, password), posts it to the registration endpoint, and initiates a session. To integrate the registration process, one needs to create a credential on the client side. In place of the password, as done in legacy applications, the verified credential is sent to ZPK-based applications.

Here is the usual process for user registration in a portable identity solution based on zero-knowledge proof:

Zero knowledge proof-based user registration process in portable identity solution

The process has no bearing on the remaining registration flow that might include issuing a session, sending email notifications and more.

The road ahead

As zero-knowledge proof technology progresses in the coming years, vast amounts of data and credentials are expected to be represented on a blockchain by a public identifier that reveals no user data and cannot be backward-solved for the original secret. Adapting portable identity solutions based on zero-knowledge protocols will help avoid the exposure of the ownership of attributes, thus effectively eliminating the associated threats.

Backed by ZKP technology, portable identity solutions have the potential to take data privacy and security to the next level in a wide array of applications, from feeding data into the Internet of Things (IoT) to fraud prevention systems. 

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