basicdhexample.java

sip CMSEnvelopedData

package chapter4;

import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.MessageDigest;

import javax.crypto.KeyAgreement;
import javax.crypto.spec.DHParameterSpec;

/**
 * Two party key agreement using Diffie-Hellman
 */
public class BasicDHExample
{
    private static BigInteger g512 = new BigInteger(
            "153d5d6172adb43045b68ae8e1de1070b6137005686d29d3d73a7"
          + "749199681ee5b212c9b96bfdcfa5b20cd5e3fd2044895d609cf9b"
          + "410b7a0f12ca1cb9a428cc", 16);
    private static BigInteger p512 = new BigInteger(
            "9494fec095f3b85ee286542b3836fc81a5dd0a0349b4c239dd387"
          + "44d488cf8e31db8bcb7d33b41abb9e5a33cca9144b1cef332c94b"
          + "f0573bf047a3aca98cdf3b", 16);

    public static void main(
        String[]    args)
        throws Exception
    {
        DHParameterSpec             dhParams = new DHParameterSpec(p512, g512);

        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DH", "BC");

        keyGen.initialize(dhParams, Utils.createFixedRandom());

        // set up
        KeyAgreement aKeyAgree = KeyAgreement.getInstance("DH", "BC");
        KeyPair      aPair = keyGen.generateKeyPair();
        KeyAgreement bKeyAgree = KeyAgreement.getInstance("DH", "BC");
        KeyPair      bPair = keyGen.generateKeyPair();
        
        // two party agreement
        aKeyAgree.init(aPair.getPrivate());
        bKeyAgree.init(bPair.getPrivate());

        aKeyAgree.doPhase(bPair.getPublic(), true);
        bKeyAgree.doPhase(aPair.getPublic(), true);

        //      generate the key bytes
        MessageDigest	hash = MessageDigest.getInstance("SHA1", "BC");
        byte[] aShared = hash.digest(aKeyAgree.generateSecret());
        byte[] bShared = hash.digest(bKeyAgree.generateSecret());
        
        System.out.println(Utils.toHex(aShared));
        System.out.println(Utils.toHex(bShared));
    }
}