ECC with Java

README

The examples to demonstrate how to use Elliptic Curve Cryptography in Java from 
  http://www.academicpub.org/PaperInfo.aspx?PaperID=14496

ECCKeyAgreement.java

// The following code is from http://www.academicpub.org/PaperInfo.aspx?PaperID=14496 .
import java.math.BigInteger;
import java.security.*;
import java.security.spec.*;
import javax.crypto.KeyAgreement;

public class ECCKeyAgreement {
  public static void main(String[] args) throws Exception {
    KeyPairGenerator kpg;
    kpg = KeyPairGenerator.getInstance("EC","SunEC");
    ECGenParameterSpec ecsp;

    ecsp = new ECGenParameterSpec("secp192k1");
    kpg.initialize(ecsp);

    KeyPair kpU = kpg.genKeyPair();
    PrivateKey privKeyU = kpU.getPrivate();
    PublicKey pubKeyU = kpU.getPublic();
    System.out.println("User U: " + privKeyU.toString());
    System.out.println("User U: " + pubKeyU.toString());

    KeyPair kpV = kpg.genKeyPair();
    PrivateKey privKeyV = kpV.getPrivate();
    PublicKey pubKeyV = kpV.getPublic();
    System.out.println("User V: " + privKeyV.toString());
    System.out.println("User V: " + pubKeyV.toString());

    KeyAgreement ecdhU = KeyAgreement.getInstance("ECDH");
    ecdhU.init(privKeyU);
    ecdhU.doPhase(pubKeyV,true);

    KeyAgreement ecdhV = KeyAgreement.getInstance("ECDH");
    ecdhV.init(privKeyV);
    ecdhV.doPhase(pubKeyU,true);

    System.out.println("Secret computed by U: 0x" + 
                       (new BigInteger(1, ecdhU.generateSecret()).toString(16)).toUpperCase());
    System.out.println("Secret computed by V: 0x" + 
                       (new BigInteger(1, ecdhV.generateSecret()).toString(16)).toUpperCase());
  }
}

ECCKeyGeneration.java

// The following code is from http://www.academicpub.org/PaperInfo.aspx?PaperID=14496 .
import java.security.*;
import java.security.spec.*;

public class ECCKeyGeneration {
  public static void main(String[] args) throws Exception {
    KeyPairGenerator kpg;
    kpg = KeyPairGenerator.getInstance("EC","SunEC");
    ECGenParameterSpec ecsp;
    ecsp = new ECGenParameterSpec("secp192r1");
    kpg.initialize(ecsp);

    KeyPair kp = kpg.genKeyPair();
    PrivateKey privKey = kp.getPrivate();
    PublicKey pubKey = kp.getPublic();

    System.out.println(privKey.toString());
    System.out.println(pubKey.toString());
  }
}

ECCSignature.java

// The following code is from http://www.academicpub.org/PaperInfo.aspx?PaperID=14496 .
import java.math.BigInteger;
import java.security.*;
import java.security.spec.*;

public class ECCSignature {
  public static void main(String[] args) throws Exception {
    KeyPairGenerator kpg;
    kpg = KeyPairGenerator.getInstance("EC","SunEC");

    ECGenParameterSpec ecsp;
    ecsp = new ECGenParameterSpec("sect163k1");
    kpg.initialize(ecsp);

    KeyPair kp = kpg.genKeyPair();
    PrivateKey privKey = kp.getPrivate();
    PublicKey pubKey = kp.getPublic();
    System.out.println(privKey.toString());
    System.out.println(pubKey.toString());
    
    Signature ecdsa;
    ecdsa = Signature.getInstance("SHA1withECDSA","SunEC");
    ecdsa.initSign(privKey);

    String text = "In teaching others we teach ourselves";
    System.out.println("Text: " + text);
    byte[] baText = text.getBytes("UTF-8");

    ecdsa.update(baText);
    byte[] baSignature = ecdsa.sign();
    System.out.println("Signature: 0x" + (new BigInteger(1, baSignature).toString(16)).toUpperCase());

    Signature signature;
    signature = Signature.getInstance("SHA1withECDSA","SunEC");
    signature.initVerify(pubKey);
    signature.update(baText);
    boolean result = signature.verify(baSignature);
    System.out.println("Valid: " + result);
  }
}

sir how to convert biginteger into ecpoint ??like

BigInteger S = java.math.BigInteger.valueOf(0);
BigInteger M = s.multiply(temp);
S = P.multiply(temp);ECPoint R = S; 
```// error in converting BigInteger to ECPoint.. 

please help me to convert this ECDH for three parties AS there is error as it support only 2 parties