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March 18, 2019 11:36
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/* | |
A Lisitsa, 2019, The code below was taken without any changes from | |
https://docs.oracle.com/javase/8/docs/technotes/guides/security/crypto/CryptoSpec.html#DH3Ex | |
*/ | |
/* | |
* Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved. | |
* | |
* Redistribution and use in source and binary forms, with or without | |
* modification, are permitted provided that the following conditions | |
* are met: | |
* | |
* - Redistributions of source code must retain the above copyright | |
* notice, this list of conditions and the following disclaimer. | |
* | |
* - Redistributions in binary form must reproduce the above copyright | |
* notice, this list of conditions and the following disclaimer in the | |
* documentation and/or other materials provided with the distribution. | |
* | |
* - Neither the name of Oracle nor the names of its | |
* contributors may be used to endorse or promote products derived | |
* from this software without specific prior written permission. | |
* | |
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS | |
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, | |
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR | |
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, | |
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, | |
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR | |
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF | |
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING | |
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS | |
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
*/ | |
import java.security.*; | |
import java.security.spec.*; | |
import javax.crypto.*; | |
import javax.crypto.spec.*; | |
import javax.crypto.interfaces.*; | |
/* | |
* This program executes the Diffie-Hellman key agreement protocol between | |
* 3 parties: Alice, Bob, and Carol using a shared 2048-bit DH parameter. | |
*/ | |
public class DHKeyAgreement3 { | |
private DHKeyAgreement3() {} | |
public static void main(String argv[]) throws Exception { | |
// Alice creates her own DH key pair with 2048-bit key size | |
System.out.println("ALICE: Generate DH keypair ..."); | |
KeyPairGenerator aliceKpairGen = KeyPairGenerator.getInstance("DH"); | |
aliceKpairGen.initialize(2048); | |
KeyPair aliceKpair = aliceKpairGen.generateKeyPair(); | |
// This DH parameters can also be constructed by creating a | |
// DHParameterSpec object using agreed-upon values | |
DHParameterSpec dhParamShared = ((DHPublicKey)aliceKpair.getPublic()).getParams(); | |
// Bob creates his own DH key pair using the same params | |
System.out.println("BOB: Generate DH keypair ..."); | |
KeyPairGenerator bobKpairGen = KeyPairGenerator.getInstance("DH"); | |
bobKpairGen.initialize(dhParamShared); | |
KeyPair bobKpair = bobKpairGen.generateKeyPair(); | |
// Carol creates her own DH key pair using the same params | |
System.out.println("CAROL: Generate DH keypair ..."); | |
KeyPairGenerator carolKpairGen = KeyPairGenerator.getInstance("DH"); | |
carolKpairGen.initialize(dhParamShared); | |
KeyPair carolKpair = carolKpairGen.generateKeyPair(); | |
// duncan creates his own DH key pair using the same params | |
System.out.println("DUNCAN: Generate DH keypair ..."); | |
KeyPairGenerator duncanKpairGen = KeyPairGenerator.getInstance("DH"); | |
carolKpairGen.initialize(dhParamShared); | |
KeyPair duncanKpair = duncanKpairGen.generateKeyPair(); | |
// Alice initialize | |
System.out.println("ALICE: Initialize ..."); | |
KeyAgreement aliceKeyAgree = KeyAgreement.getInstance("DH"); | |
aliceKeyAgree.init(aliceKpair.getPrivate()); | |
// Bob initialize | |
System.out.println("BOB: Initialize ..."); | |
KeyAgreement bobKeyAgree = KeyAgreement.getInstance("DH"); | |
bobKeyAgree.init(bobKpair.getPrivate()); | |
// Carol initialize | |
System.out.println("CAROL: Initialize ..."); | |
KeyAgreement carolKeyAgree = KeyAgreement.getInstance("DH"); | |
carolKeyAgree.init(carolKpair.getPrivate()); | |
// duncan initalise | |
System.out.println("duncan: Initialize ..."); | |
KeyAgreement duncanKeyAgree = KeyAgreement.getInstance("DH"); | |
duncanKeyAgree.init(duncanKpair.getPrivate()); | |
// Alice uses Duncan's public key | |
Key ac = aliceKeyAgree.doPhase(duncanKpair.getPublic(), false); | |
// Bob uses Alice's public key | |
Key ba = bobKeyAgree.doPhase(aliceKpair.getPublic(), false); | |
// Carol uses Bob's public key | |
Key cb = carolKeyAgree.doPhase(bobKpair.getPublic(), false); | |
// duncan uses Carols public key | |
Key db = duncanKeyAgree.doPhase(carolKpair.getPublic(), false); | |
// Alice uses Carol's result from above | |
aliceKeyAgree.doPhase(db, true); | |
// Bob uses Alice's result from above | |
bobKeyAgree.doPhase(ac, true); | |
// Carol uses Bob's result from above | |
carolKeyAgree.doPhase(ba, true); | |
// duncan uses carols result from above | |
duncanKeyAgree.doPhase(cb, true); | |
// Alice, Bob and Carol compute their secrets | |
byte[] aliceSharedSecret = aliceKeyAgree.generateSecret(); | |
System.out.println("Alice secret: " + toHexString(aliceSharedSecret)); | |
byte[] bobSharedSecret = bobKeyAgree.generateSecret(); | |
System.out.println("Bob secret: " + toHexString(bobSharedSecret)); | |
byte[] carolSharedSecret = carolKeyAgree.generateSecret(); | |
System.out.println("Carol secret: " + toHexString(carolSharedSecret)); | |
byte[] duncanSharedSecret = duncanKeyAgree.generateSecret(); | |
System.out.println("Duncan secret: " + toHexString(carolSharedSecret)); | |
// Compare Alice and Bob | |
if (!java.util.Arrays.equals(aliceSharedSecret, bobSharedSecret)) | |
throw new Exception("Alice and Bob differ"); | |
System.out.println("Alice and Bob are the same"); | |
// Compare Bob and Carol | |
if (!java.util.Arrays.equals(bobSharedSecret, carolSharedSecret)) | |
throw new Exception("Bob and Carol differ"); | |
System.out.println("Bob and Carol are the same"); | |
// Compare duncan and Carol | |
if (!java.util.Arrays.equals(duncanSharedSecret, carolSharedSecret)) | |
throw new Exception("Duncan and Carol differ"); | |
System.out.println("Duncan and Carol are the same"); | |
} | |
/* | |
* Converts a byte to hex digit and writes to the supplied buffer | |
*/ | |
private static void byte2hex(byte b, StringBuffer buf) { | |
char[] hexChars = { '0', '1', '2', '3', '4', '5', '6', '7', '8', | |
'9', 'A', 'B', 'C', 'D', 'E', 'F' }; | |
int high = ((b & 0xf0) >> 4); | |
int low = (b & 0x0f); | |
buf.append(hexChars[high]); | |
buf.append(hexChars[low]); | |
} | |
/* | |
* Converts a byte array to hex string | |
*/ | |
private static String toHexString(byte[] block) { | |
StringBuffer buf = new StringBuffer(); | |
int len = block.length; | |
for (int i = 0; i < len; i++) { | |
byte2hex(block[i], buf); | |
if (i < len-1) { | |
buf.append(":"); | |
} | |
} | |
return buf.toString(); | |
} | |
} |
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