ojluni/src/main/java/sun/security/ssl/DHCrypt.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 1996, 2012, 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.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 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) {
         try {
             KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("DiffieHellman");
             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);
         }
     }


     /**
      * 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 = modulus;
         this.base = base;
         try {
             KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("DiffieHellman");
             DHParameterSpec params = new DHParameterSpec(modulus, base);
             kpg.initialize(params, random);

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

             publicValue = spec.getY();
         } 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 IOException {
         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 new RuntimeException("Could not generate secret", e);
         }
     }

     // 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;
     }
 }
	/*
	* Copyright (c) 1996, 2012, 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.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 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) {
	try {
	KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("DiffieHellman");
	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);
	}
	}


	/**
	* 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 = modulus;
	this.base = base;
	try {
	KeyPairGenerator kpg = JsseJce.getKeyPairGenerator("DiffieHellman");
	DHParameterSpec params = new DHParameterSpec(modulus, base);
	kpg.initialize(params, random);

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

	publicValue = spec.getY();
	} 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 IOException {
	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 new RuntimeException("Could not generate secret", e);
	}
	}

	// 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;
	}
	}