Package com.tnsai.payment.x402

Class TransferAuthorization

java.lang.Object

com.tnsai.payment.x402.TransferAuthorization

public final class TransferAuthorization
extends Object

Builds the EIP-712 typed-data hash pair for an EIP-3009 transferWithAuthorization call — the payload an x402 client signs to authorise a one-time USDC transfer without an on-chain approval round-trip.

Two hashes come out:

• Domain separator = keccak256(EIP712Domain(...)), scoped to the token contract that will verify the signature (the asset address from the 402 response).
• Struct hash = keccak256(TransferWithAuthorization(...)), binding from, to, value, validAfter, validBefore, and nonce.

The wallet receives both as an EIP712TypedData record and applies the EIP-712 prefix and secp256k1 signing on top — specifically keccak256(0x1901 || domainSeparator || structHash) — so this class never touches private-key material.

Why we don't use web3j's StructuredDataEncoder

StructuredDataEncoder round-trips through JSON Schema parsing, which is heavier than necessary for this fixed schema. Inlining the encoding keeps the broker's hot path tight and the implementation legible alongside the EIP-712 / EIP-3009 spec.

Since:

0.10.5 (TNS-449 P3)

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	TransferAuthorization.Builder	Builder for TransferAuthorization.

Method Summary

Modifier and Type	Method	Description
static TransferAuthorization.Builder	builder()
String	from()
byte[]	nonce()
String	to()
EIP712TypedData	toTypedData()	EIP-712 typed data: the two 32-byte hashes the wallet will sign over.
BigInteger	validAfter()
BigInteger	validBefore()
BigInteger	value()

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Details

builder

public static TransferAuthorization.Builder builder()

from

public String from()

to

public String to()

value

public BigInteger value()

validAfter

public BigInteger validAfter()

validBefore

public BigInteger validBefore()

nonce

public byte[] nonce()

toTypedData

public EIP712TypedData toTypedData()

EIP-712 typed data: the two 32-byte hashes the wallet will sign over.