jdk/src/share/classes/sun/security/ssl/DHCrypt.java - edge/openjdk - Git at Google

 /*
  * Copyright (c) 1996, 2015, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */


 package sun.security.ssl;

 import java.util.Map;
 import java.util.HashMap;
 import java.util.Collections;
 import java.util.regex.Pattern;
 import java.util.regex.Matcher;
 import java.math.BigInteger;
 import java.security.*;
 import java.io.IOException;
 import javax.net.ssl.SSLHandshakeException;
 import javax.crypto.SecretKey;
 import javax.crypto.KeyAgreement;
 import javax.crypto.interfaces.DHPublicKey;
 import javax.crypto.spec.*;
 import java.util.EnumSet;

 import sun.security.util.KeyUtil;

 /**
  * This class implements the Diffie-Hellman key exchange algorithm.
  * D-H means combining your private key with your partners public key to
  * generate a number. The peer does the same with its private key and our
  * public key. Through the magic of Diffie-Hellman we both come up with the
  * same number. This number is secret (discounting MITM attacks) and hence
  * called the shared secret. It has the same length as the modulus, e.g. 512
  * or 1024 bit. Man-in-the-middle attacks are typically countered by an
  * independent authentication step using certificates (RSA, DSA, etc.).
  *
  * The thing to note is that the shared secret is constant for two partners
  * with constant private keys. This is often not what we want, which is why
  * it is generally a good idea to create a new private key for each session.
  * Generating a private key involves one modular exponentiation assuming
  * suitable D-H parameters are available.
  *
  * General usage of this class (TLS DHE case):
  *  . if we are server, call DHCrypt(keyLength,random). This generates
  *    an ephemeral keypair of the request length.
  *  . if we are client, call DHCrypt(modulus, base, random). This
  *    generates an ephemeral keypair using the parameters specified by
  *    the server.
  *  . send parameters and public value to remote peer
  *  . receive peers ephemeral public key
  *  . call getAgreedSecret() to calculate the shared secret
  *
  * In TLS the server chooses the parameter values itself, the client must use
  * those sent to it by the server.
  *
  * The use of ephemeral keys as described above also achieves what is called
  * "forward secrecy". This means that even if the authentication keys are
  * broken at a later date, the shared secret remains secure. The session is
  * compromised only if the authentication keys are already broken at the
  * time the key exchange takes place and an active MITM attack is used.
  * This is in contrast to straightforward encrypting RSA key exchanges.
  *
  * @author David Brownell
  */
 final class DHCrypt {

     // group parameters (prime modulus and generator)
     private BigInteger modulus;                 // P (aka N)
     private BigInteger base;                    // G (aka alpha)

     // our private key (including private component x)
     private PrivateKey privateKey;

     // public component of our key, X = (g ^ x) mod p
     private BigInteger publicValue;             // X (aka y)

     // the times to recove from failure if public key validation
     private static int MAX_FAILOVER_TIMES = 2;

     /**
      * Generate a Diffie-Hellman keypair of the specified size.
      */
     DHCrypt(int keyLength, SecureRandom random) {
         this(keyLength,
                 ParametersHolder.definedParams.get(keyLength), random);
     }

     /**
      * Generate a Diffie-Hellman keypair using the specified parameters.
      *
      * @param modulus the Diffie-Hellman modulus P
      * @param base the Diffie-Hellman base G
      */
     DHCrypt(BigInteger modulus, BigInteger base, SecureRandom random) {
         this(modulus.bitLength(),
                 new DHParameterSpec(modulus, base), random);
     }

     /**
      * Generate a Diffie-Hellman keypair using the specified size and
      * parameters.
      */
     private DHCrypt(int keyLength,
             DHParameterSpec params, SecureRandom random) {

         try {
             KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("DiffieHellman");
             if (params != null) {
                 kpg.initialize(params, random);
             } else {
                 kpg.initialize(keyLength, random);
             }

             DHPublicKeySpec spec = generateDHPublicKeySpec(kpg);
             if (spec == null) {
                 throw new RuntimeException("Could not generate DH keypair");
             }

             publicValue = spec.getY();
             modulus = spec.getP();
             base = spec.getG();
         } catch (GeneralSecurityException e) {
             throw new RuntimeException("Could not generate DH keypair", e);
         }
     }

     static DHPublicKeySpec getDHPublicKeySpec(PublicKey key) {
         if (key instanceof DHPublicKey) {
             DHPublicKey dhKey = (DHPublicKey)key;
             DHParameterSpec params = dhKey.getParams();
             return new DHPublicKeySpec(dhKey.getY(),
                                     params.getP(), params.getG());
         }
         try {
             KeyFactory factory = JsseJce.getKeyFactory("DH");
             return factory.getKeySpec(key, DHPublicKeySpec.class);
         } catch (Exception e) {
             throw new RuntimeException(e);
         }
     }


     /** Returns the Diffie-Hellman modulus. */
     BigInteger getModulus() {
         return modulus;
     }

     /** Returns the Diffie-Hellman base (generator).  */
     BigInteger getBase() {
         return base;
     }

     /**
      * Gets the public key of this end of the key exchange.
      */
     BigInteger getPublicKey() {
         return publicValue;
     }

     /**
      * Get the secret data that has been agreed on through Diffie-Hellman
      * key agreement protocol.  Note that in the two party protocol, if
      * the peer keys are already known, no other data needs to be sent in
      * order to agree on a secret.  That is, a secured message may be
      * sent without any mandatory round-trip overheads.
      *
      * <P>It is illegal to call this member function if the private key
      * has not been set (or generated).
      *
      * @param  peerPublicKey the peer's public key.
      * @param  keyIsValidated whether the {@code peerPublicKey} has beed
      *         validated
      * @return the secret, which is an unsigned big-endian integer
      *         the same size as the Diffie-Hellman modulus.
      */
     SecretKey getAgreedSecret(BigInteger peerPublicValue,
             boolean keyIsValidated) throws SSLHandshakeException {
         try {
             KeyFactory kf = JsseJce.getKeyFactory("DiffieHellman");
             DHPublicKeySpec spec =
                         new DHPublicKeySpec(peerPublicValue, modulus, base);
             PublicKey publicKey = kf.generatePublic(spec);
             KeyAgreement ka = JsseJce.getKeyAgreement("DiffieHellman");

             // validate the Diffie-Hellman public key
             if (!keyIsValidated &&
                     !KeyUtil.isOracleJCEProvider(ka.getProvider().getName())) {
                 try {
                     KeyUtil.validate(spec);
                 } catch (InvalidKeyException ike) {
                     // prefer handshake_failure alert to internal_error alert
                     throw new SSLHandshakeException(ike.getMessage());
                 }
             }

             ka.init(privateKey);
             ka.doPhase(publicKey, true);
             return ka.generateSecret("TlsPremasterSecret");
         } catch (GeneralSecurityException e) {
             throw (SSLHandshakeException) new SSLHandshakeException(
                 "Could not generate secret").initCause(e);
         }
     }

     // Check constraints of the specified DH public key.
     void checkConstraints(AlgorithmConstraints constraints,
             BigInteger peerPublicValue) throws SSLHandshakeException {

         try {
             KeyFactory kf = JsseJce.getKeyFactory("DiffieHellman");
             DHPublicKeySpec spec =
                         new DHPublicKeySpec(peerPublicValue, modulus, base);
             DHPublicKey publicKey = (DHPublicKey)kf.generatePublic(spec);

             // check constraints of DHPublicKey
             if (!constraints.permits(
                     EnumSet.of(CryptoPrimitive.KEY_AGREEMENT), publicKey)) {
                 throw new SSLHandshakeException(
                     "DHPublicKey does not comply to algorithm constraints");
             }
         } catch (GeneralSecurityException gse) {
             throw (SSLHandshakeException) new SSLHandshakeException(
                     "Could not generate DHPublicKey").initCause(gse);
         }
     }

     // Generate and validate DHPublicKeySpec
     private DHPublicKeySpec generateDHPublicKeySpec(KeyPairGenerator kpg)
             throws GeneralSecurityException {

         boolean doExtraValiadtion =
                     (!KeyUtil.isOracleJCEProvider(kpg.getProvider().getName()));
         for (int i = 0; i <= MAX_FAILOVER_TIMES; i++) {
             KeyPair kp = kpg.generateKeyPair();
             privateKey = kp.getPrivate();
             DHPublicKeySpec spec = getDHPublicKeySpec(kp.getPublic());

             // validate the Diffie-Hellman public key
             if (doExtraValiadtion) {
                 try {
                     KeyUtil.validate(spec);
                 } catch (InvalidKeyException ivke) {
                     if (i == MAX_FAILOVER_TIMES) {
                         throw ivke;
                     }
                     // otherwise, ignore the exception and try the next one
                     continue;
                 }
             }

             return spec;
         }

         return null;
     }

     // lazy initialization holder class idiom for static default parameters
     //
     // See Effective Java Second Edition: Item 71.
     private static class ParametersHolder {
         private final static boolean debugIsOn =
                 (Debug.getInstance("ssl") != null) && Debug.isOn("sslctx");

         //
         // Default DH ephemeral parameters
         //
         private static final BigInteger g2 = BigInteger.valueOf(2);

         private static final BigInteger p512 = new BigInteger(   // generated
                 "D87780E15FF50B4ABBE89870188B049406B5BEA98AB23A02" +
                 "41D88EA75B7755E669C08093D3F0CA7FC3A5A25CF067DCB9" +
                 "A43DD89D1D90921C6328884461E0B6D3", 16);
         private static final BigInteger p768 = new BigInteger(   // RFC 2409
                 "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" +
                 "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" +
                 "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" +
                 "E485B576625E7EC6F44C42E9A63A3620FFFFFFFFFFFFFFFF", 16);

         private static final BigInteger p1024 = new BigInteger(  // RFC 2409
                 "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" +
                 "29024E088A67CC74020BBEA63B139B22514A08798E3404DD" +
                 "EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" +
                 "E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" +
                 "EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" +
                 "FFFFFFFFFFFFFFFF", 16);
         private static final BigInteger p2048 = new BigInteger(  // TLS FEDHE
                 "FFFFFFFFFFFFFFFFADF85458A2BB4A9AAFDC5620273D3CF1" +
                 "D8B9C583CE2D3695A9E13641146433FBCC939DCE249B3EF9" +
                 "7D2FE363630C75D8F681B202AEC4617AD3DF1ED5D5FD6561" +
                 "2433F51F5F066ED0856365553DED1AF3B557135E7F57C935" +
                 "984F0C70E0E68B77E2A689DAF3EFE8721DF158A136ADE735" +
                 "30ACCA4F483A797ABC0AB182B324FB61D108A94BB2C8E3FB" +
                 "B96ADAB760D7F4681D4F42A3DE394DF4AE56EDE76372BB19" +
                 "0B07A7C8EE0A6D709E02FCE1CDF7E2ECC03404CD28342F61" +
                 "9172FE9CE98583FF8E4F1232EEF28183C3FE3B1B4C6FAD73" +
                 "3BB5FCBC2EC22005C58EF1837D1683B2C6F34A26C1B2EFFA" +
                 "886B423861285C97FFFFFFFFFFFFFFFF", 16);

         private static final BigInteger[] supportedPrimes = {
                 p512, p768, p1024, p2048};

         // a measure of the uncertainty that prime modulus p is not a prime
         //
         // see BigInteger.isProbablePrime(int certainty)
         private final static int PRIME_CERTAINTY = 120;

         // the known security property, jdk.tls.server.defaultDHEParameters
         private final static String PROPERTY_NAME =
                 "jdk.tls.server.defaultDHEParameters";

         private static final Pattern spacesPattern = Pattern.compile("\\s+");

         private final static Pattern syntaxPattern = Pattern.compile(
                 "(\\{[0-9A-Fa-f]+,[0-9A-Fa-f]+\\})" +
                 "(,\\{[0-9A-Fa-f]+,[0-9A-Fa-f]+\\})*");

         private static final Pattern paramsPattern = Pattern.compile(
                 "\\{([0-9A-Fa-f]+),([0-9A-Fa-f]+)\\}");

         // cache of predefined default DH ephemeral parameters
         private final static Map<Integer,DHParameterSpec> definedParams;

         static {
             String property = AccessController.doPrivileged(
                 new PrivilegedAction<String>() {
                     public String run() {
                         return Security.getProperty(PROPERTY_NAME);
                     }
                 });

             if (property != null && !property.isEmpty()) {
                 // remove double quote marks from beginning/end of the property
                 if (property.length() >= 2 && property.charAt(0) == '"' &&
                         property.charAt(property.length() - 1) == '"') {
                     property = property.substring(1, property.length() - 1);
                 }

                 property = property.trim();
             }

             if (property != null && !property.isEmpty()) {
                 Matcher spacesMatcher = spacesPattern.matcher(property);
                 property = spacesMatcher.replaceAll("");

                 if (debugIsOn) {
                     System.out.println("The Security Property " +
                             PROPERTY_NAME + ": " + property);
                 }
             }

             Map<Integer,DHParameterSpec> defaultParams = new HashMap<>();
             if (property != null && !property.isEmpty()) {
                 Matcher syntaxMatcher = syntaxPattern.matcher(property);
                 if (syntaxMatcher.matches()) {
                     Matcher paramsFinder = paramsPattern.matcher(property);
                     while(paramsFinder.find()) {
                         String primeModulus = paramsFinder.group(1);
                         BigInteger p = new BigInteger(primeModulus, 16);
                         if (!p.isProbablePrime(PRIME_CERTAINTY)) {
                             if (debugIsOn) {
                                 System.out.println(
                                     "Prime modulus p in Security Property, " +
                                     PROPERTY_NAME + ", is not a prime: " +
                                     primeModulus);
                             }

                             continue;
                         }

                         String baseGenerator = paramsFinder.group(2);
                         BigInteger g = new BigInteger(baseGenerator, 16);

                         DHParameterSpec spec = new DHParameterSpec(p, g);
                         int primeLen = p.bitLength();
                         defaultParams.put(primeLen, spec);
                     }
                 } else if (debugIsOn) {
                     System.out.println("Invalid Security Property, " +
                             PROPERTY_NAME + ", definition");
                 }
             }

             for (BigInteger p : supportedPrimes) {
                 int primeLen = p.bitLength();
                 defaultParams.putIfAbsent(primeLen, new DHParameterSpec(p, g2));
             }

             definedParams =
                     Collections.<Integer,DHParameterSpec>unmodifiableMap(
                                                                 defaultParams);
         }
     }
 }
	/*
	* Copyright (c) 1996, 2015, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/


	package sun.security.ssl;

	import java.util.Map;
	import java.util.HashMap;
	import java.util.Collections;
	import java.util.regex.Pattern;
	import java.util.regex.Matcher;
	import java.math.BigInteger;
	import java.security.*;
	import java.io.IOException;
	import javax.net.ssl.SSLHandshakeException;
	import javax.crypto.SecretKey;
	import javax.crypto.KeyAgreement;
	import javax.crypto.interfaces.DHPublicKey;
	import javax.crypto.spec.*;
	import java.util.EnumSet;

	import sun.security.util.KeyUtil;

	/**
	* This class implements the Diffie-Hellman key exchange algorithm.
	* D-H means combining your private key with your partners public key to
	* generate a number. The peer does the same with its private key and our
	* public key. Through the magic of Diffie-Hellman we both come up with the
	* same number. This number is secret (discounting MITM attacks) and hence
	* called the shared secret. It has the same length as the modulus, e.g. 512
	* or 1024 bit. Man-in-the-middle attacks are typically countered by an
	* independent authentication step using certificates (RSA, DSA, etc.).
	*
	* The thing to note is that the shared secret is constant for two partners
	* with constant private keys. This is often not what we want, which is why
	* it is generally a good idea to create a new private key for each session.
	* Generating a private key involves one modular exponentiation assuming
	* suitable D-H parameters are available.
	*
	* General usage of this class (TLS DHE case):
	* . if we are server, call DHCrypt(keyLength,random). This generates
	* an ephemeral keypair of the request length.
	* . if we are client, call DHCrypt(modulus, base, random). This
	* generates an ephemeral keypair using the parameters specified by
	* the server.
	* . send parameters and public value to remote peer
	* . receive peers ephemeral public key
	* . call getAgreedSecret() to calculate the shared secret
	*
	* In TLS the server chooses the parameter values itself, the client must use
	* those sent to it by the server.
	*
	* The use of ephemeral keys as described above also achieves what is called
	* "forward secrecy". This means that even if the authentication keys are
	* broken at a later date, the shared secret remains secure. The session is
	* compromised only if the authentication keys are already broken at the
	* time the key exchange takes place and an active MITM attack is used.
	* This is in contrast to straightforward encrypting RSA key exchanges.
	*
	* @author David Brownell
	*/
	final class DHCrypt {

	// group parameters (prime modulus and generator)
	private BigInteger modulus; // P (aka N)
	private BigInteger base; // G (aka alpha)

	// our private key (including private component x)
	private PrivateKey privateKey;

	// public component of our key, X = (g ^ x) mod p
	private BigInteger publicValue; // X (aka y)

	// the times to recove from failure if public key validation
	private static int MAX_FAILOVER_TIMES = 2;

	/**
	* Generate a Diffie-Hellman keypair of the specified size.
	*/
	DHCrypt(int keyLength, SecureRandom random) {
	this(keyLength,
	ParametersHolder.definedParams.get(keyLength), random);
	}

	/**
	* Generate a Diffie-Hellman keypair using the specified parameters.
	*
	* @param modulus the Diffie-Hellman modulus P
	* @param base the Diffie-Hellman base G
	*/
	DHCrypt(BigInteger modulus, BigInteger base, SecureRandom random) {
	this(modulus.bitLength(),
	new DHParameterSpec(modulus, base), random);
	}

	/**
	* Generate a Diffie-Hellman keypair using the specified size and
	* parameters.
	*/
	private DHCrypt(int keyLength,
	DHParameterSpec params, SecureRandom random) {

	try {
	KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("DiffieHellman");
	if (params != null) {
	kpg.initialize(params, random);
	} else {
	kpg.initialize(keyLength, random);
	}

	DHPublicKeySpec spec = generateDHPublicKeySpec(kpg);
	if (spec == null) {
	throw new RuntimeException("Could not generate DH keypair");
	}

	publicValue = spec.getY();
	modulus = spec.getP();
	base = spec.getG();
	} catch (GeneralSecurityException e) {
	throw new RuntimeException("Could not generate DH keypair", e);
	}
	}

	static DHPublicKeySpec getDHPublicKeySpec(PublicKey key) {
	if (key instanceof DHPublicKey) {
	DHPublicKey dhKey = (DHPublicKey)key;
	DHParameterSpec params = dhKey.getParams();
	return new DHPublicKeySpec(dhKey.getY(),
	params.getP(), params.getG());
	}
	try {
	KeyFactory factory = JsseJce.getKeyFactory("DH");
	return factory.getKeySpec(key, DHPublicKeySpec.class);
	} catch (Exception e) {
	throw new RuntimeException(e);
	}
	}


	/** Returns the Diffie-Hellman modulus. */
	BigInteger getModulus() {
	return modulus;
	}

	/** Returns the Diffie-Hellman base (generator). */
	BigInteger getBase() {
	return base;
	}

	/**
	* Gets the public key of this end of the key exchange.
	*/
	BigInteger getPublicKey() {
	return publicValue;
	}

	/**
	* Get the secret data that has been agreed on through Diffie-Hellman
	* key agreement protocol. Note that in the two party protocol, if
	* the peer keys are already known, no other data needs to be sent in
	* order to agree on a secret. That is, a secured message may be
	* sent without any mandatory round-trip overheads.
	*
	* <P>It is illegal to call this member function if the private key
	* has not been set (or generated).
	*
	* @param peerPublicKey the peer's public key.
	* @param keyIsValidated whether the {@code peerPublicKey} has beed
	* validated
	* @return the secret, which is an unsigned big-endian integer
	* the same size as the Diffie-Hellman modulus.
	*/
	SecretKey getAgreedSecret(BigInteger peerPublicValue,
	boolean keyIsValidated) throws SSLHandshakeException {
	try {
	KeyFactory kf = JsseJce.getKeyFactory("DiffieHellman");
	DHPublicKeySpec spec =
	new DHPublicKeySpec(peerPublicValue, modulus, base);
	PublicKey publicKey = kf.generatePublic(spec);
	KeyAgreement ka = JsseJce.getKeyAgreement("DiffieHellman");

	// validate the Diffie-Hellman public key
	if (!keyIsValidated &&
	!KeyUtil.isOracleJCEProvider(ka.getProvider().getName())) {
	try {
	KeyUtil.validate(spec);
	} catch (InvalidKeyException ike) {
	// prefer handshake_failure alert to internal_error alert
	throw new SSLHandshakeException(ike.getMessage());
	}
	}

	ka.init(privateKey);
	ka.doPhase(publicKey, true);
	return ka.generateSecret("TlsPremasterSecret");
	} catch (GeneralSecurityException e) {
	throw (SSLHandshakeException) new SSLHandshakeException(
	"Could not generate secret").initCause(e);
	}
	}

	// Check constraints of the specified DH public key.
	void checkConstraints(AlgorithmConstraints constraints,
	BigInteger peerPublicValue) throws SSLHandshakeException {

	try {
	KeyFactory kf = JsseJce.getKeyFactory("DiffieHellman");
	DHPublicKeySpec spec =
	new DHPublicKeySpec(peerPublicValue, modulus, base);
	DHPublicKey publicKey = (DHPublicKey)kf.generatePublic(spec);

	// check constraints of DHPublicKey
	if (!constraints.permits(
	EnumSet.of(CryptoPrimitive.KEY_AGREEMENT), publicKey)) {
	throw new SSLHandshakeException(
	"DHPublicKey does not comply to algorithm constraints");
	}
	} catch (GeneralSecurityException gse) {
	throw (SSLHandshakeException) new SSLHandshakeException(
	"Could not generate DHPublicKey").initCause(gse);
	}
	}

	// Generate and validate DHPublicKeySpec
	private DHPublicKeySpec generateDHPublicKeySpec(KeyPairGenerator kpg)
	throws GeneralSecurityException {

	boolean doExtraValiadtion =
	(!KeyUtil.isOracleJCEProvider(kpg.getProvider().getName()));
	for (int i = 0; i <= MAX_FAILOVER_TIMES; i++) {
	KeyPair kp = kpg.generateKeyPair();
	privateKey = kp.getPrivate();
	DHPublicKeySpec spec = getDHPublicKeySpec(kp.getPublic());

	// validate the Diffie-Hellman public key
	if (doExtraValiadtion) {
	try {
	KeyUtil.validate(spec);
	} catch (InvalidKeyException ivke) {
	if (i == MAX_FAILOVER_TIMES) {
	throw ivke;
	}
	// otherwise, ignore the exception and try the next one
	continue;
	}
	}

	return spec;
	}

	return null;
	}

	// lazy initialization holder class idiom for static default parameters
	//
	// See Effective Java Second Edition: Item 71.
	private static class ParametersHolder {
	private final static boolean debugIsOn =
	(Debug.getInstance("ssl") != null) && Debug.isOn("sslctx");

	//
	// Default DH ephemeral parameters
	//
	private static final BigInteger g2 = BigInteger.valueOf(2);

	private static final BigInteger p512 = new BigInteger( // generated
	"D87780E15FF50B4ABBE89870188B049406B5BEA98AB23A02" +
	"41D88EA75B7755E669C08093D3F0CA7FC3A5A25CF067DCB9" +
	"A43DD89D1D90921C6328884461E0B6D3", 16);
	private static final BigInteger p768 = new BigInteger( // RFC 2409
	"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" +
	"29024E088A67CC74020BBEA63B139B22514A08798E3404DD" +
	"EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" +
	"E485B576625E7EC6F44C42E9A63A3620FFFFFFFFFFFFFFFF", 16);

	private static final BigInteger p1024 = new BigInteger( // RFC 2409
	"FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD1" +
	"29024E088A67CC74020BBEA63B139B22514A08798E3404DD" +
	"EF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245" +
	"E485B576625E7EC6F44C42E9A637ED6B0BFF5CB6F406B7ED" +
	"EE386BFB5A899FA5AE9F24117C4B1FE649286651ECE65381" +
	"FFFFFFFFFFFFFFFF", 16);
	private static final BigInteger p2048 = new BigInteger( // TLS FEDHE
	"FFFFFFFFFFFFFFFFADF85458A2BB4A9AAFDC5620273D3CF1" +
	"D8B9C583CE2D3695A9E13641146433FBCC939DCE249B3EF9" +
	"7D2FE363630C75D8F681B202AEC4617AD3DF1ED5D5FD6561" +
	"2433F51F5F066ED0856365553DED1AF3B557135E7F57C935" +
	"984F0C70E0E68B77E2A689DAF3EFE8721DF158A136ADE735" +
	"30ACCA4F483A797ABC0AB182B324FB61D108A94BB2C8E3FB" +
	"B96ADAB760D7F4681D4F42A3DE394DF4AE56EDE76372BB19" +
	"0B07A7C8EE0A6D709E02FCE1CDF7E2ECC03404CD28342F61" +
	"9172FE9CE98583FF8E4F1232EEF28183C3FE3B1B4C6FAD73" +
	"3BB5FCBC2EC22005C58EF1837D1683B2C6F34A26C1B2EFFA" +
	"886B423861285C97FFFFFFFFFFFFFFFF", 16);

	private static final BigInteger[] supportedPrimes = {
	p512, p768, p1024, p2048};

	// a measure of the uncertainty that prime modulus p is not a prime
	//
	// see BigInteger.isProbablePrime(int certainty)
	private final static int PRIME_CERTAINTY = 120;

	// the known security property, jdk.tls.server.defaultDHEParameters
	private final static String PROPERTY_NAME =
	"jdk.tls.server.defaultDHEParameters";

	private static final Pattern spacesPattern = Pattern.compile("\\s+");

	private final static Pattern syntaxPattern = Pattern.compile(
	"(\\{[0-9A-Fa-f]+,[0-9A-Fa-f]+\\})" +
	"(,\\{[0-9A-Fa-f]+,[0-9A-Fa-f]+\\})*");

	private static final Pattern paramsPattern = Pattern.compile(
	"\\{([0-9A-Fa-f]+),([0-9A-Fa-f]+)\\}");

	// cache of predefined default DH ephemeral parameters
	private final static Map<Integer,DHParameterSpec> definedParams;

	static {
	String property = AccessController.doPrivileged(
	new PrivilegedAction<String>() {
	public String run() {
	return Security.getProperty(PROPERTY_NAME);
	}
	});

	if (property != null && !property.isEmpty()) {
	// remove double quote marks from beginning/end of the property
	if (property.length() >= 2 && property.charAt(0) == '"' &&
	property.charAt(property.length() - 1) == '"') {
	property = property.substring(1, property.length() - 1);
	}

	property = property.trim();
	}

	if (property != null && !property.isEmpty()) {
	Matcher spacesMatcher = spacesPattern.matcher(property);
	property = spacesMatcher.replaceAll("");

	if (debugIsOn) {
	System.out.println("The Security Property " +
	PROPERTY_NAME + ": " + property);
	}
	}

	Map<Integer,DHParameterSpec> defaultParams = new HashMap<>();
	if (property != null && !property.isEmpty()) {
	Matcher syntaxMatcher = syntaxPattern.matcher(property);
	if (syntaxMatcher.matches()) {
	Matcher paramsFinder = paramsPattern.matcher(property);
	while(paramsFinder.find()) {
	String primeModulus = paramsFinder.group(1);
	BigInteger p = new BigInteger(primeModulus, 16);
	if (!p.isProbablePrime(PRIME_CERTAINTY)) {
	if (debugIsOn) {
	System.out.println(
	"Prime modulus p in Security Property, " +
	PROPERTY_NAME + ", is not a prime: " +
	primeModulus);
	}

	continue;
	}

	String baseGenerator = paramsFinder.group(2);
	BigInteger g = new BigInteger(baseGenerator, 16);

	DHParameterSpec spec = new DHParameterSpec(p, g);
	int primeLen = p.bitLength();
	defaultParams.put(primeLen, spec);
	}
	} else if (debugIsOn) {
	System.out.println("Invalid Security Property, " +
	PROPERTY_NAME + ", definition");
	}
	}

	for (BigInteger p : supportedPrimes) {
	int primeLen = p.bitLength();
	defaultParams.putIfAbsent(primeLen, new DHParameterSpec(p, g2));
	}

	definedParams =
	Collections.<Integer,DHParameterSpec>unmodifiableMap(
	defaultParams);
	}
	}
	}