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Crate x402_chain_eip155

Crate x402_chain_eip155 

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Expand description

EIP-155 (EVM) chain support for the x402 payment protocol.

This crate provides implementations of the x402 payment protocol for EVM-compatible blockchains using the EIP-155 chain ID standard. It supports both V1 and V2 protocol versions with the “exact” payment scheme based on ERC-3009 transferWithAuthorization.

§Features

  • V1 and V2 Protocol Support: Implements both protocol versions with network name (V1) and CAIP-2 chain ID (V2) addressing
  • ERC-3009 Payments: Gasless token transfers using transferWithAuthorization
  • Smart Wallet Support: EIP-1271 for deployed wallets, EIP-6492 for counterfactual wallets
  • Multiple Signers: Round-robin signer selection for load distribution
  • Nonce Management: Automatic nonce tracking with pending transaction awareness

§Architecture

The crate is organized into several modules:

  • chain - Core EVM chain types, providers, and configuration
  • v1_eip155_exact - V1 protocol implementation with network names
  • v2_eip155_exact - V2 protocol implementation with CAIP-2 chain IDs

§Feature Flags

  • server - Server-side price tag generation
  • client - Client-side payment signing
  • facilitator - Facilitator-side payment verification and settlement
  • telemetry - OpenTelemetry tracing support

§Usage Examples

§Server: Creating a Price Tag

ⓘ
use x402_chain_eip155::{V1Eip155Exact, KnownNetworkEip155};
use x402_types::networks::USDC;

// Get USDC deployment on Base
let usdc = USDC::base();

// Create a price tag for 1 USDC
let price_tag = V1Eip155Exact::price_tag(
    "0x742d35Cc6634C0532925a3b844Bc9e7595f0bEb",
    usdc.amount(1_000_000u64),
);

§Client: Signing a Payment

ⓘ
use x402_chain_eip155::V1Eip155ExactClient;
use alloy_signer_local::PrivateKeySigner;

let signer = PrivateKeySigner::random();
let client = V1Eip155ExactClient::new(signer);

// Use client to sign payment candidates
let candidates = client.accept(&payment_required);

§Facilitator: Verifying and Settling

ⓘ
use x402_chain_eip155::{V1Eip155Exact, Eip155ChainProvider};
use x402_types::scheme::X402SchemeFacilitatorBuilder;

let provider = Eip155ChainProvider::from_config(&config).await?;
let facilitator = V1Eip155Exact.build(provider, None)?;

// Verify payment
let verify_response = facilitator.verify(&verify_request).await?;

// Settle payment
let settle_response = facilitator.settle(&settle_request).await?;

Re-exports§

pub use v1_eip155_exact::V1Eip155Exact;
pub use v2_eip155_exact::V2Eip155Exact;
pub use v2_eip155_upto::V2Eip155Upto;
pub use v1_eip155_exact::client::V1Eip155ExactClient;
pub use v2_eip155_exact::client::V2Eip155ExactClient;
pub use v2_eip155_upto::client::V2Eip155UptoClient;
pub use chain::types::decimal_u256;

Modules§

chain
EVM chain support for x402 payments via EIP-155.
v1_eip155_exact
V1 EIP-155 “exact” payment scheme implementation.
v2_eip155_exact
V2 EIP-155 “exact” payment scheme implementation.
v2_eip155_upto
V2 EIP-155 “upto” payment scheme implementation.

Traits§

KnownNetworkEip155
Trait providing convenient methods to get instances for well-known EVM networks (eip155 namespace).