@sun-protocol/permit2-sdk

TypeScript SDK for Permit2 allowance transfers on the TRON network.

Permit2 enables token approvals to be shared and managed across different applications, using off-chain EIP-712 signatures to grant time-limited, scoped allowances.

Installation

npm install @sun-protocol/permit2-sdk

Quick Start

import { TronWeb } from 'tronweb';
import { AllowanceTransfer } from '@sun-protocol/permit2-sdk';

const tronWeb = new TronWeb({
  fullHost: 'https://api.trongrid.io',
  privateKey: '<YOUR_PRIVATE_KEY>',
});

const PERMIT2_ADDRESS = 'T...'; // Permit2 contract address on TRON
const isTestnet = false;

const transfer = new AllowanceTransfer(tronWeb, PERMIT2_ADDRESS, isTestnet);

Query Allowance

const allowance = await transfer.allowance(
  'TOwnerAddress...',
  'TTokenAddress...',
  'TSpenderAddress...'
);

console.log(allowance.amount);     // bigint
console.log(allowance.expiration); // bigint
console.log(allowance.nonce);      // bigint

Generate Permit Signature (Single Token)

const permitWithSig = await transfer.generatePermitSignature(
  {
    owner: 'TOwnerAddress...',
    token: 'TTokenAddress...',
    amount: 1000000n,                // token amount (uint160)
    deadline: '1735689600',          // allowance expiration (unix timestamp)
  },
  'TSpenderAddress...',             // spender
  '1735689600'                      // signature deadline (unix timestamp)
);

console.log(permitWithSig.signature); // 0x...
console.log(permitWithSig.details);   // { token, amount, expiration, nonce }

Generate Permit Signature (Batch)

const batchPermitWithSig = await transfer.generatePermitBatchSignature(
  [
    {
      owner: 'TOwnerAddress...',
      token: 'TTokenA...',
      amount: 1000000n,
      deadline: '1735689600',
    },
    {
      owner: 'TOwnerAddress...',
      token: 'TTokenB...',
      amount: 2000000n,
      deadline: '1735689600',
    },
  ],
  'TSpenderAddress...',
  '1735689600'
);

console.log(batchPermitWithSig.signature); // 0x...
console.log(batchPermitWithSig.details);   // PermitDetails[]

Generate Sign Data Without Signing

If you need to handle signing externally (e.g. hardware wallet, frontend wallet), use the sign data methods:

// Single
const { domain, permitSingle } = await transfer.generatePermitSignData(
  params, spender, sigDeadline
);

// Batch
const { domain, permitBatch } = await transfer.generatePermitBatchSignData(
  paramsList, spender, sigDeadline
);

These return the EIP-712 domain and message for you to sign with your own signer.

API Reference

AllowanceTransfer

Constructor

new AllowanceTransfer(tronWeb: TronWeb, permit2Address: string, isTestnet: boolean)

Parameter	Type	Description
tronWeb	TronWeb	TronWeb instance with signer configured
permit2Address	string	Permit2 contract address (Base58 or hex)
isTestnet	boolean	true for Nile testnet, false for mainnet

Methods

Method	Returns	Description
allowance(owner, token, spender)	Promise<Allowance>	Query on-chain allowance state
generatePermitSignData(params, spender, sigDeadline)	Promise<{ domain, permitSingle }>	Build EIP-712 typed data for single permit
generatePermitBatchSignData(paramsList, spender, sigDeadline)	Promise<{ domain, permitBatch }>	Build EIP-712 typed data for batch permit
generatePermitSignature(params, spender, sigDeadline)	Promise<PermitSingleWithSignature>	Sign a single token permit
generatePermitBatchSignature(paramsList, spender, sigDeadline)	Promise<PermitBatchWithSignature>	Sign a batch token permit

Types

interface PermitParams {
  owner: string;    // Owner address (Base58 or 0x hex)
  token: string;    // Token address (Base58 or 0x hex)
  amount: bigint;   // Approval amount (uint160)
  deadline: string; // Allowance expiration (unix timestamp)
}

interface Allowance {
  amount: bigint;
  expiration: bigint;
  nonce: bigint;
}

interface PermitSingleWithSignature {
  details: PermitDetails;
  spender: string;
  sigDeadline: string;
  signature: Hex;
}

interface PermitBatchWithSignature {
  details: PermitDetails[];
  spender: string;
  sigDeadline: string;
  signature: Hex;
}

Utilities

import { toEvmHex, toBase58, Address } from '@sun-protocol/permit2-sdk';

// Convert TRON Base58 address to EVM hex
toEvmHex('TJRabPrwbZy45sbavfcjinPJC18kjpRTv8'); // '0x...'

// Convert hex address to TRON Base58
toBase58('0x...');  // 'T...'

// Address helper — auto-detects format
const addr = new Address('TJRabPrwbZy45sbavfcjinPJC18kjpRTv8');
addr.hex;    // '0x...'
addr.base58; // 'TJRab...'

Network Support

Network	Chain ID
TRON Mainnet	728126428
TRON Nile Testnet	3448148188

Development

npm install
npm run build      # Compile TypeScript
npm run dev        # Watch mode
npm run lint       # Type check
npm run format     # Prettier
npm test           # Run tests

License

MIT