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Signature

Convert signature between r, s, v and compressed string format.

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

For converting {r ,s ,v} signature to string, create a Sign.SignatureData object from params r, s ,v. Use Numeric.hexStringToByteArray to convert string to byte array

To compress Sign.SignatureData to compressed signature string, use KaiaSignatureData.getSignatureString with the signature object as param

For converting string signature to {r ,s ,v}, First convert the string signature to byte array. Use Numeric.hexStringToByteArray to convert string to byte array

Extract r, s, v components from the byte array. R is the first 32 indices, S is the next 32 indices and V is the last indice

You can use Numeric.toHexString to convert each components from byte array to string

SignatureUtilsExample.java

package org.web3j.example.utils;

import org.web3j.crypto.KaiaSignatureData;

import org.web3j.crypto.Sign;

import org.web3j.utils.Numeric;

public class SignatureUtilsExample {

public static void main(String[] args) {

// convert from {r, s, v} signature to string

byte[] r = Numeric.hexStringToByteArray("0xbaabb5a43a047e75e41a77b88fa7a5bf89e5227f1c8e40bfdfbcceb8164521ed");

byte[] s = Numeric.hexStringToByteArray("0x678f3a7b600169b800828065cda112aa28291311a5dbb729480444a2b905f6e6");

byte[] v = Numeric.hexStringToByteArray("0x0");

Sign.SignatureData obj = new Sign.SignatureData(v, r, s);

String signature = KaiaSignatureData.getSignatureString(obj);

System.out.println("From {r, s, v} to string " + signature);

// convert from signature string to {r, s, v}

byte[] signatureBytes = Numeric.hexStringToByteArray("0xbaabb5a43a047e75e41a77b88fa7a5bf89e5227f1c8e40bfdfbcceb8164521ed678f3a7b600169b800828065cda112aa28291311a5dbb729480444a2b905f6e600");

byte[] convertedR = new byte[32];

byte[] convertedS = new byte[32];

byte[] convertedV= new byte[1];

// r is the first 32 bytes

System.arraycopy(signatureBytes, 0, convertedR, 0, 32);

// s is the next 32 bytes

System.arraycopy(signatureBytes, 32, convertedS, 0, 32);

// v is the last byte

convertedV[0] = signatureBytes[64];

System.out.println("Converted R " + Numeric.toHexString(convertedR));

System.out.println("Converted S " + Numeric.toHexString(convertedS));

System.out.println("Converted V " + Numeric.toHexString(convertedV));

}

}

output

❯ java SignatureUtilsExample.java

0xbaabb5a43a047e75e41a77b88fa7a5bf89e5227f1c8e40bfdfbcceb8164521ed678f3a7b600169b800828065cda112aa28291311a5dbb729480444a2b905f6e600