Use bouncy castle SHA256 with ECDSA - Java Security

Java examples for Security:DSA

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Description

Use bouncy castle SHA256 with ECDSA

Demo Code

import java.io.UnsupportedEncodingException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.NoSuchAlgorithmException;
import java.security.NoSuchProviderException;
import java.security.SecureRandom;
import java.security.Security;
import java.security.Signature;
import java.security.SignatureException;
import java.util.Date;
import java.sql.Timestamp;

import org.bouncycastle.jce.ECNamedCurveTable;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.jce.spec.ECParameterSpec;

public class ecdsa {

    public static void GetTimestamp(String info) {
        System.out.println(info + new Timestamp((new Date()).getTime()));
    }/*ww  w.ja va  2s  .  com*/

    public static byte[] GenerateSignature(String plaintext, KeyPair keys)
            throws SignatureException, UnsupportedEncodingException,
            InvalidKeyException, NoSuchAlgorithmException,
            NoSuchProviderException {
        Signature ecdsaSign = Signature
                .getInstance("SHA256withECDSA", "BC");
        ecdsaSign.initSign(keys.getPrivate());
        ecdsaSign.update(plaintext.getBytes("UTF-8"));
        byte[] signature = ecdsaSign.sign();
        System.out.println(signature.toString());
        return signature;
    }

    public static boolean ValidateSignature(String plaintext, KeyPair pair,
            byte[] signature) throws SignatureException,
            InvalidKeyException, UnsupportedEncodingException,
            NoSuchAlgorithmException, NoSuchProviderException {
        Signature ecdsaVerify = Signature.getInstance("SHA256withECDSA",
                "BC");
        ecdsaVerify.initVerify(pair.getPublic());
        ecdsaVerify.update(plaintext.getBytes("UTF-8"));
        return ecdsaVerify.verify(signature);
    }

    public static KeyPair GenerateKeys() throws NoSuchAlgorithmException,
            NoSuchProviderException, InvalidAlgorithmParameterException {
        //  Other named curves can be found in http://www.bouncycastle.org/wiki/display/JA1/Supported+Curves+%28ECDSA+and+ECGOST%29
        ECParameterSpec ecSpec = ECNamedCurveTable
                .getParameterSpec("B-571");

        KeyPairGenerator g = KeyPairGenerator.getInstance("ECDSA", "BC");

        g.initialize(ecSpec, new SecureRandom());

        return g.generateKeyPair();
    }

    public static void main(String[] args) throws Exception {

        Security.addProvider(new BouncyCastleProvider());

        String plaintext = "Simple plain text";
        GetTimestamp("Key Generation started: ");
        KeyPair keys = GenerateKeys();
        //    System.out.println(keys.getPublic().toString());
        //    System.out.println(keys.getPrivate().toString());
        GetTimestamp("Key Generation ended: ");

        GetTimestamp("Signature Generation started: ");
        byte[] signature = GenerateSignature(plaintext, keys);
        GetTimestamp("Signature Generation ended: ");

        GetTimestamp("Validation started: ");
        boolean isValidated = ValidateSignature(plaintext, keys, signature);
        System.out.println("Result: " + isValidated);
        GetTimestamp("Validation ended: ");

    }

}

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