Java DSAParams tutorial with examples

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Interface to a DSA-specific set of key parameters, which defines a DSA key family.

Introduction

Interface to a DSA-specific set of key parameters, which defines a DSA key family.

DSA (Digital Signature Algorithm) is defined in NIST's FIPS-186.

Example

The following code shows how to use DSAParams from java.security.interfaces.

Example 1 

import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.interfaces.DSAParams;
import java.security.interfaces.DSAPrivateKey;
import java.security.interfaces.DSAPublicKey;

public class Main {
    public static void main(String[] argv) throws Exception {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
        keyGen.initialize(1024);/*  ww    w .   d e   mo  2    s . c   o  m */
        KeyPair keypair = keyGen.genKeyPair();
        DSAPrivateKey privateKey = (DSAPrivateKey) keypair.getPrivate();
        DSAPublicKey publicKey = (DSAPublicKey) keypair.getPublic();

        DSAParams dsaParams = privateKey.getParams();
        BigInteger p = dsaParams.getP();
        BigInteger q = dsaParams.getQ();
        BigInteger g = dsaParams.getG();
        BigInteger x = privateKey.getX();
        BigInteger y = publicKey.getY();
    }
}

Example 2 

import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.PrivateKey;
import java.security.PublicKey;
import java.security.interfaces.DSAParams;
import java.security.interfaces.DSAPrivateKey;
import java.security.interfaces.DSAPublicKey;
import java.security.spec.DSAPrivateKeySpec;
import java.security.spec.DSAPublicKeySpec;
import java.security.spec.KeySpec;

public class Main {
    public static void main(String[] argv) throws Exception {
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DSA");
        keyGen.initialize(1024);/*  w  ww   .   d  e m   o  2s    .  c  o m */
        KeyPair keypair = keyGen.genKeyPair();
        DSAPrivateKey privateKey = (DSAPrivateKey) keypair.getPrivate();
        DSAPublicKey publicKey = (DSAPublicKey) keypair.getPublic();

        DSAParams dsaParams = privateKey.getParams();
        BigInteger p = dsaParams.getP();
        BigInteger q = dsaParams.getQ();
        BigInteger g = dsaParams.getG();
        BigInteger x = privateKey.getX();
        BigInteger y = publicKey.getY();

        KeyFactory keyFactory = KeyFactory.getInstance("DSA");
        KeySpec privateKeySpec = new DSAPrivateKeySpec(x, p, q, g);
        PrivateKey privateKey1 = keyFactory.generatePrivate(privateKeySpec);
    }
}
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