Signing & Verification of secp256k1 in Java

signAndVerifySecp256K1Util.java

/*
Create Keys using:

Private Key(2 Step: Create & convert to newer PEM format):
openssl ecparam -name secp256k1 -genkey -out privateKey.pem
openssl pkcs8 -topk8 -inform pem -in privateKey.pem -outform pem -nocrypt -out privateKeyv2.pem

Public Key(using Private Key):
openssl ec -in privateKeyv2.pem -pubout -out publicKeyv2.pem
*/

package com.example.demo.service;

import java.nio.file.Files;
import java.nio.file.Paths;
import java.security.KeyFactory;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.Signature;
import java.security.spec.PKCS8EncodedKeySpec;
import java.security.spec.X509EncodedKeySpec;
import java.util.Base64;

public class signAndVerifySecp256K1Util {

    private static final String ENCRYPTION_ALGORITHM = "EC";
    private static final String HASH_ENCRYPTION_ALGO = "SHA256withECDSA";

    public String sign() throws Exception {

        PrivateKey privateKey = getPemPrivateKey(
                "/Users/kiwi/workspace/training/pem-keys/privateKeyv2.pem",
                ENCRYPTION_ALGORITHM
        );
        String plainText = "Hello";
        Signature ecdsaSign = Signature.getInstance(HASH_ENCRYPTION_ALGO);
        ecdsaSign.initSign(privateKey);
        ecdsaSign.update(plainText.getBytes("UTF-8"));
        byte[] signature = ecdsaSign.sign();
        String sig = Base64.getEncoder().encodeToString(signature);
        return sig;
    }

    public boolean verify(String signature) throws Exception {
        PublicKey publicKey= getPemPubKey(
                "/Users/kiwi/workspace/training/pem-keys/publicKeyv2.pem",
                ENCRYPTION_ALGORITHM
        );
        Signature ecdsaVerify = Signature.getInstance(HASH_ENCRYPTION_ALGO);

        ecdsaVerify.initVerify(publicKey);
        ecdsaVerify.update(signature.getBytes("UTF-8"));
        boolean result = ecdsaVerify.verify(
                Base64.getMimeDecoder().decode(signature)
        );
        return result;

    }

    private PrivateKey getPemPrivateKey(String filename, String algorithm) throws Exception {
        String temp = new String(Files.readAllBytes(Paths.get(filename)));


        String privKeyPEM = temp.replace("-----BEGIN PRIVATE KEY-----\n","");
        privKeyPEM = privKeyPEM.replace("-----END PRIVATE KEY-----","");

        byte[] decoded =  Base64.getMimeDecoder().decode(privKeyPEM.getBytes());

        PKCS8EncodedKeySpec spec = new PKCS8EncodedKeySpec(decoded);
        KeyFactory kf = KeyFactory.getInstance(algorithm);
        return kf.generatePrivate(spec);
    }

    private PublicKey getPemPubKey(String filename, String algorithm) throws Exception {
        String temp = new String(Files.readAllBytes(Paths.get(filename)));
        String pubKeyPEM = temp.replace("-----BEGIN PUBLIC KEY-----\n","");
        pubKeyPEM = pubKeyPEM.replace("-----END PUBLIC KEY-----","");

        byte[] decoded =  Base64.getMimeDecoder().decode(pubKeyPEM);

        X509EncodedKeySpec spec = new X509EncodedKeySpec(decoded);
        KeyFactory kf = KeyFactory.getInstance(algorithm);
        return kf.generatePublic(spec);
    }
}

Hello sir

I tried it but it gives me error Exception in thread "main" java.security.spec.InvalidKeySpecException: java.security.InvalidKeyException: IOException : version mismatch: (supported: 00, parsed:
any idea bro?

thanks