Java DSAParams getQ()

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Java DSAParams getQ() Returns the subprime, q.

Syntax

The method getQ() from DSAParams is declared as: 

public BigInteger getQ();

Return

The method getQ() returns the subprime, q.

Example

The following code shows how to use Java DSAParams getQ()

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);//  w  w  w   .   d  e m  o   2 s  .  c   om  
        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    w w   . d e    m  o 2 s   . c    om  
        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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