Sign Transaction

Sign a created transaction

As seen earlier, the transaction process has been split in 3 steps. Once a transaction has been created, it must be signed. The signature is a unique identifier created by hashing the input parameters provided while creating the transaction and wallet information of the signer. This is useful for verification purposes and prevention of forgery.

The signTransaction function creates a signature for a transaction.

Basic Syntax

The function is called as follows:

import { signTransaction } from 'arweavekit/transaction'

const signedTransaction = await signTransaction({params}) 

Input Parameters

The following params are available for this function and they must be passed in as an object:

  • key: JWKInterface (optional): The private key for the wallet signing the transaction. When using in web apps, this field can be left empty or the use_wallet string can be passed in to trigger a web wallet. The wallet key file can be loaded as follows:

import { readFileSync } from 'fs';

const key = JSON.parse(readFileSync('wallet.json').toString());
  • environment: 'local' | 'mainnet' (optional) : The environment on which the transaction was created.

An arlocal instance must be running on port 1984 for the function to work with the local environment. To create one, simply run npx arlocal in the command line. Learn more about arlocal here.

  • createdTransaction: object : The transaction object created in the earlier step.

  • postTransaction: boolean (optional): This boolean enables the posting of the transaction to Arweave using the signTransaction function itself.

const signedTransaction = await signTransaction({
    createdTransaction: createdTransaction,
    key: { KEY_OBJECT },
    environment: 'mainnet',

This call signs a created transaction on mainnet on a node environment.

Returned Data

The function call returns the following data depending on input parameters:

  • A signed object of type Transaction is returned by Arweave.

    • The signature key will be populated with a base64URL encoded signature hash with the help of the RSA algorithm.

    • The id of a transaction is only received after posting the transaction on Arweave.

    • On selecting the postTransaction option the function returns a status object along with the transaction object. status: 200 and statusText: 'OK' indicates a successful post request on Arweave.

    • The transaction is signed on the selected environment (local or mainnet).

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