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Legacy Account Key

Import necessary classes from the Web3j and kaia libraries(web3j-ext).

Create a Web3j instance with the specified BAOBAB_URL

Also, you can change the default provider. For example, using the alchemy provider.

Load a credential from private key and get its address

Define any message to sign

Set the block number to be the latest block in the kaia network

Sign the message and convert the signature to string

Recover the address and compare it to the original address

Shut down the Web3j instance

SignMsgWithLegacyExample.java

package org.web3j.example.accountKey;

import org.web3j.tx.response.PollingTransactionReceiptProcessor;

import org.web3j.tx.response.TransactionReceiptProcessor;

import org.web3j.example.keySample;

import java.io.IOException;

import org.web3j.crypto.KlayCredentials;

import org.web3j.crypto.KlaySignatureData;

import org.web3j.crypto.Sign.SignatureData;

import org.web3j.protocol.http.HttpService;

import org.web3j.protocol.kaia.Web3j;

import org.web3j.protocol.kaia.core.method.response.KlayRecoverFromMessageResponse;

/**

*

*/

public class SignMsgWithLegacyExample implements keySample {

/**

*

*/

public static void run() throws Exception {

Web3j web3j = Web3j.build(new HttpService(keySample.BAOBAB_URL));

KlayCredentials credentials1 = KlayCredentials.create(keySample.LEGACY_KEY_privkey);

String from = credentials1.getAddress();

String message = "0xdeadbeef";

String blockNumber = "latest";

SignatureData signature = KlaySignatureData.signPrefixedMessage(message, credentials1);

String result = KlaySignatureData.getSignatureString(signature);

KlayRecoverFromMessageResponse response = web3j.klayRecoverFromMessage(from, message, result, blockNumber)

.send();

System.out.println("Original address : " + from);

System.out.println("Result address : " + response.getResult());

web3j.shutdown();

}

}

output

❯ java SignMsgWithLegacyExample.java

Original address : 0xa2a8854b1802d8cd5de631e690817c253d6a9153

Result address : 0xa2a8854b1802d8cd5de631e690817c253d6a9153