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2010-06-01T05:02:05Z

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в 17:44, 31 мая 2010

2010-05-31T17:44:27Z

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== Diffie-Hellman Key Agreement ==



<source lang="java">
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.MessageDigest;
import java.security.SecureRandom;
import java.security.Security;
import javax.crypto.KeyAgreement;
import javax.crypto.spec.DHParameterSpec;
public class MainClass {
private static BigInteger g512 = new BigInteger("1234567890", 16);
private static BigInteger p512 = new BigInteger("1234567890", 16);
public static void main(String[] args) throws Exception {
Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
DHParameterSpec dhParams = new DHParameterSpec(p512, g512);
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("DH", "BC");
keyGen.initialize(dhParams, new SecureRandom());
KeyAgreement aKeyAgree = KeyAgreement.getInstance("DH", "BC");
KeyPair aPair = keyGen.generateKeyPair();
KeyAgreement bKeyAgree = KeyAgreement.getInstance("DH", "BC");
KeyPair bPair = keyGen.generateKeyPair();
aKeyAgree.init(aPair.getPrivate());
bKeyAgree.init(bPair.getPrivate());
aKeyAgree.doPhase(bPair.getPublic(), true);
bKeyAgree.doPhase(aPair.getPublic(), true);
MessageDigest hash = MessageDigest.getInstance("SHA1", "BC");
System.out.println(new String(hash.digest(aKeyAgree.generateSecret())));
System.out.println(new String(hash.digest(bKeyAgree.generateSecret())));
}
}</source>



== Diffie-Hellman with Elliptic Curve ==



<source lang="java">
import java.math.BigInteger;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.MessageDigest;
import java.security.SecureRandom;
import java.security.Security;
import java.security.spec.ECFieldFp;
import java.security.spec.ECParameterSpec;
import java.security.spec.ECPoint;
import java.security.spec.EllipticCurve;
import javax.crypto.KeyAgreement;
public class MainClass {
public static void main(String[] args) throws Exception {
Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("ECDH", "BC");
EllipticCurve curve = new EllipticCurve(new ECFieldFp(new BigInteger(
"fffffffffffffffffffffffffffffffeffffffffffffffff", 16)), new BigInteger(
"fffffffffffffffffffffffffffffffefffffffffffffffc", 16), new BigInteger(
"fffffffffffffffffffffffffffffffefffffffffffffffc", 16));
ECParameterSpec ecSpec = new ECParameterSpec(curve, new ECPoint(new BigInteger(
"fffffffffffffffffffffffffffffffefffffffffffffffc", 16), new BigInteger(
"fffffffffffffffffffffffffffffffefffffffffffffffc", 16)), new BigInteger(
"fffffffffffffffffffffffffffffffefffffffffffffffc", 16), 1);
keyGen.initialize(ecSpec, new SecureRandom());
KeyAgreement aKeyAgree = KeyAgreement.getInstance("ECDH", "BC");
KeyPair aPair = keyGen.generateKeyPair();
KeyAgreement bKeyAgree = KeyAgreement.getInstance("ECDH", "BC");
KeyPair bPair = keyGen.generateKeyPair();
aKeyAgree.init(aPair.getPrivate());
bKeyAgree.init(bPair.getPrivate());
aKeyAgree.doPhase(bPair.getPublic(), true);
bKeyAgree.doPhase(aPair.getPublic(), true);
MessageDigest hash = MessageDigest.getInstance("SHA1", "BC");
System.out.println(new String(hash.digest(aKeyAgree.generateSecret())));
System.out.println(new String(hash.digest(bKeyAgree.generateSecret())));
}
}</source>



== Generating a Parameter Set for the Diffie-Hellman Key Agreement Algorithm ==



<source lang="java">
import java.security.AlgorithmParameterGenerator;
import java.security.AlgorithmParameters;
import javax.crypto.spec.DHParameterSpec;
public class Main {
public static void main(String[] argv) throws Exception {
AlgorithmParameterGenerator paramGen = AlgorithmParameterGenerator.getInstance("DH");
paramGen.init(1024);
AlgorithmParameters params = paramGen.generateParameters();
DHParameterSpec dhSpec = (DHParameterSpec) params.getParameterSpec(DHParameterSpec.class);
System.out.println("" + dhSpec.getP() + "," + dhSpec.getG() + "," + dhSpec.getL());
}
}</source>



== Implementing the Diffie-Hellman key exchange ==



<source lang="java">
import java.math.BigInteger;
import java.security.KeyFactory;
import java.security.KeyPair;
import java.security.KeyPairGenerator;
import java.security.SecureRandom;
import javax.crypto.spec.DHParameterSpec;
import javax.crypto.spec.DHPublicKeySpec;
public class MainClass {
public final static int pValue = 47;
public final static int gValue = 71;
public final static int XaValue = 9;
public final static int XbValue = 14;
public static void main(String[] args) throws Exception {
BigInteger p = new BigInteger(Integer.toString(pValue));
BigInteger g = new BigInteger(Integer.toString(gValue));
BigInteger Xa = new BigInteger(Integer.toString(XaValue));
BigInteger Xb = new BigInteger(Integer.toString(XbValue));
createKey();
int bitLength = 512; // 512 bits
SecureRandom rnd = new SecureRandom();
p = BigInteger.probablePrime(bitLength, rnd);
g = BigInteger.probablePrime(bitLength, rnd);

createSpecificKey(p, g);
}
public static void createKey() throws Exception {
KeyPairGenerator kpg = KeyPairGenerator.getInstance("DiffieHellman");
kpg.initialize(512);
KeyPair kp = kpg.generateKeyPair();
KeyFactory kfactory = KeyFactory.getInstance("DiffieHellman");
DHPublicKeySpec kspec = (DHPublicKeySpec) kfactory.getKeySpec(kp.getPublic(),
DHPublicKeySpec.class);
}
public static void createSpecificKey(BigInteger p, BigInteger g) throws Exception {
KeyPairGenerator kpg = KeyPairGenerator.getInstance("DiffieHellman");
DHParameterSpec param = new DHParameterSpec(p, g);
kpg.initialize(param);
KeyPair kp = kpg.generateKeyPair();
KeyFactory kfactory = KeyFactory.getInstance("DiffieHellman");
DHPublicKeySpec kspec = (DHPublicKeySpec) kfactory.getKeySpec(kp.getPublic(),
DHPublicKeySpec.class);
}
}</source>

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Admin: 1 версия

в 17:44, 31 мая 2010