HTTP 402 + Zero-Knowledge Integration Overview

1. Introduction

402zk is the fusion of the x402 payment protocol and ZK-SNARK (Zero-Knowledge Succinct Non-Interactive Argument of Knowledge) technology. Its goal is to create a trustless, anonymous, and automated micropayment infrastructure for the web and AI agents.

In a world where machines and AI communicate with each other, a direct, account-free, intermediary-free, and privacy-preserving payment mechanism becomes essential. 402zk fulfills that need by:

  • Using the HTTP 402 Payment Required response code to initiate payment requests.

Embedding ZK-SNARK proofs within transactions to fully protect user and payment data.

2. Benefits of the 402 + ZK Model

Feature
Before (Traditional HTTP)
After (HTTP 402 + ZK)

Transaction Transparency

❌ Not transparent

✅ Verifiable via proofs

User Security

❌ Identity easily exposed

✅ Data is hidden using ZKP

Automation

⚠️ Requires manual verification

✅ Proof verification is automated

Scalability

⚙️ Hard to integrate with Web3

🚀 Easy integration with blockchain / wallets

2. Background

The 402 Payment Required status code is defined in RFC 7231 but is rarely used in practice. Combining it with Zero-Knowledge Proofs (ZKPs) opens up new application possibilities:

Component
Description

HTTP 402

Allows the server to request payment from the user before accessing a resource.

ZK Proofs

Provide a mathematical proof that the user has made the payment without revealing the actual payment details.

3. Basic interaction flow

Sequence Diagram

NextHow 402zk Works

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