public static void main(String[] args) {
try {
AlgorithmParameterGenerator paramGen = AlgorithmParameterGenerator.getInstance("DSA");
paramGen.init(1024);
AlgorithmParameters params = paramGen.generateParameters();
DSAParameterSpec dsaParameterSpec = params.getParameterSpec(DSAParameterSpec.class);
KeyPairGenerator keyPairGenerator = KeyPairGenerator.getInstance("DSA");
keyPairGenerator.initialize(dsaParameterSpec);
KeyPair keyPair = keyPairGenerator.generateKeyPair();
PublicKey publicKey = keyPair.getPublic();
PrivateKey privateKey = keyPair.getPrivate();
saveKey("BpubKey", publicKey);
saveKey("BprivKey", privateKey);
} catch (NoSuchAlgorithmException
| InvalidParameterSpecException
| InvalidAlgorithmParameterException e) {
e.printStackTrace();
}
}
/**
* Generates and returns {@link DHParameterSpec}.
*
* @return {@link String}
* @see AlgorithmParameters
* @see AlgorithmParameterGenerator
*/
public static DHParameterSpec generateDiffieHellmanValues()
throws NoSuchAlgorithmException, InvalidParameterSpecException {
AlgorithmParameterGenerator parameterGenerator = AlgorithmParameterGenerator.getInstance("DH");
parameterGenerator.init(1024);
AlgorithmParameters parameters = parameterGenerator.generateParameters();
return (DHParameterSpec) parameters.getParameterSpec(DHParameterSpec.class);
}
/** Can be used to generate new parameters */
public static void main(String[] args) throws Exception {
AlgorithmParameterGenerator paramGen = AlgorithmParameterGenerator.getInstance(ALGORITHM);
paramGen.init(1024);
AlgorithmParameters params = paramGen.generateParameters();
DHParameterSpec dhSpec = params.getParameterSpec(DHParameterSpec.class);
System.out.println("l=" + dhSpec.getL());
System.out.println("g=" + dhSpec.getG());
System.out.println("p=" + dhSpec.getP());
}
private void testParameters() throws Exception {
AlgorithmParameterGenerator a = AlgorithmParameterGenerator.getInstance("DSA", "BC");
a.init(512, random);
AlgorithmParameters params = a.generateParameters();
byte[] encodeParams = params.getEncoded();
AlgorithmParameters a2 = AlgorithmParameters.getInstance("DSA", "BC");
a2.init(encodeParams);
// a and a2 should be equivalent!
byte[] encodeParams_2 = a2.getEncoded();
if (!areEqual(encodeParams, encodeParams_2)) {
fail("encode/decode parameters failed");
}
DSAParameterSpec dsaP = (DSAParameterSpec) params.getParameterSpec(DSAParameterSpec.class);
KeyPairGenerator g = KeyPairGenerator.getInstance("DSA", "BC");
g.initialize(dsaP, new SecureRandom());
KeyPair p = g.generateKeyPair();
PrivateKey sKey = p.getPrivate();
PublicKey vKey = p.getPublic();
Signature s = Signature.getInstance("DSA", "BC");
byte[] data = {1, 2, 3, 4, 5, 6, 7, 8, 9, 0};
s.initSign(sKey);
s.update(data);
byte[] sigBytes = s.sign();
s = Signature.getInstance("DSA", "BC");
s.initVerify(vKey);
s.update(data);
if (!s.verify(sigBytes)) {
fail("DSA verification failed");
}
}
/**
* Gets the public information for a DH key exchange or null if the parameters could not be made
*
* @return a PubInfo object that holds the public information for a DH key exchange or null if the
* parameters could not be made
*/
public static PubInfo getPubParams() {
try {
AlgorithmParameterGenerator paramGen = AlgorithmParameterGenerator.getInstance("DH");
paramGen.init(1024);
AlgorithmParameters params = paramGen.generateParameters();
DHParameterSpec dhSpec = (DHParameterSpec) params.getParameterSpec(DHParameterSpec.class);
BigInteger g = dhSpec.getG();
BigInteger p = dhSpec.getP();
int l = dhSpec.getL();
return new PubInfo(g, p, l);
} catch (Exception e) {
if (DEBUG) {
System.out.println("Could not make public parameters");
}
return null;
}
}
public static void main(String[] args) {
tcount = 0;
try {
ServerSocket ss = new ServerSocket(4567);
AlgorithmParameterGenerator gerador = AlgorithmParameterGenerator.getInstance("DH");
gerador.init(1024);
AlgorithmParameters parametros = gerador.generateParameters();
DHParameterSpec dhSpec = (DHParameterSpec) parametros.getParameterSpec(DHParameterSpec.class);
while (true) {
Socket s = ss.accept();
tcount++;
TServidor ts = new TServidor(s, tcount, dhSpec);
ts.start();
}
} catch (Exception e) {
e.printStackTrace();
}
}
private void testRandom(int size) throws Exception {
AlgorithmParameterGenerator a = AlgorithmParameterGenerator.getInstance("ElGamal", "BC");
a.init(size, new SecureRandom());
AlgorithmParameters params = a.generateParameters();
byte[] encodeParams = params.getEncoded();
AlgorithmParameters a2 = AlgorithmParameters.getInstance("ElGamal", "BC");
a2.init(encodeParams);
// a and a2 should be equivalent!
byte[] encodeParams_2 = a2.getEncoded();
if (!areEqual(encodeParams, encodeParams_2)) {
fail(this.getName() + ": encode/decode parameters failed");
}
DHParameterSpec elP = (DHParameterSpec) params.getParameterSpec(DHParameterSpec.class);
testGP(size, 0, elP.getG(), elP.getP());
}
AlgorithmParameters generateParameters(
ASN1ObjectIdentifier encryptionOID, SecretKey encKey, SecureRandom rand) throws CMSException {
try {
AlgorithmParameterGenerator pGen = createAlgorithmParameterGenerator(encryptionOID);
if (encryptionOID.equals(CMSAlgorithm.RC2_CBC)) {
byte[] iv = new byte[8];
rand.nextBytes(iv);
try {
pGen.init(new RC2ParameterSpec(encKey.getEncoded().length * 8, iv), rand);
} catch (InvalidAlgorithmParameterException e) {
throw new CMSException("parameters generation error: " + e, e);
}
}
return pGen.generateParameters();
} catch (NoSuchAlgorithmException e) {
return null;
} catch (GeneralSecurityException e) {
throw new CMSException("exception creating algorithm parameter generator: " + e, e);
}
}
private void run(String mode) throws Exception {
DHParameterSpec dhSkipParamSpec;
if (mode.equals("GENERATE_DH_PARAMS")) {
// Some central authority creates new DH parameters
System.out.println("Creating Diffie-Hellman parameters (takes VERY long) ...");
AlgorithmParameterGenerator paramGen = AlgorithmParameterGenerator.getInstance("DH");
paramGen.init(512);
AlgorithmParameters params = paramGen.generateParameters();
dhSkipParamSpec = (DHParameterSpec) params.getParameterSpec(DHParameterSpec.class);
} else {
// use some pre-generated, default DH parameters
System.out.println("Using SKIP Diffie-Hellman parameters");
dhSkipParamSpec = new DHParameterSpec(skip1024Modulus, skip1024Base);
}
/*
* Alice creates her own DH key pair, using the DH parameters from
* above
*/
System.out.println("ALICE: Generate DH keypair ...");
KeyPairGenerator aliceKpairGen = KeyPairGenerator.getInstance("DH");
aliceKpairGen.initialize(dhSkipParamSpec);
KeyPair aliceKpair = aliceKpairGen.generateKeyPair();
// Alice creates and initializes her DH KeyAgreement object
System.out.println("ALICE: Initialization ...");
KeyAgreement aliceKeyAgree = KeyAgreement.getInstance("DH");
aliceKeyAgree.init(aliceKpair.getPrivate());
// Alice encodes her public key, and sends it over to Bob.
byte[] alicePubKeyEnc = aliceKpair.getPublic().getEncoded();
/*
* Let's turn over to Bob. Bob has received Alice's public key
* in encoded format.
* He instantiates a DH public key from the encoded key material.
*/
KeyFactory bobKeyFac = KeyFactory.getInstance("DH");
X509EncodedKeySpec x509KeySpec = new X509EncodedKeySpec(alicePubKeyEnc);
PublicKey alicePubKey = bobKeyFac.generatePublic(x509KeySpec);
/*
* Bob gets the DH parameters associated with Alice's public key.
* He must use the same parameters when he generates his own key
* pair.
*/
DHParameterSpec dhParamSpec = ((DHPublicKey) alicePubKey).getParams();
// Bob creates his own DH key pair
System.out.println("BOB: Generate DH keypair ...");
KeyPairGenerator bobKpairGen = KeyPairGenerator.getInstance("DH");
bobKpairGen.initialize(dhParamSpec);
KeyPair bobKpair = bobKpairGen.generateKeyPair();
// Bob creates and initializes his DH KeyAgreement object
System.out.println("BOB: Initialization ...");
KeyAgreement bobKeyAgree = KeyAgreement.getInstance("DH");
bobKeyAgree.init(bobKpair.getPrivate());
// Bob encodes his public key, and sends it over to Alice.
byte[] bobPubKeyEnc = bobKpair.getPublic().getEncoded();
/*
* Alice uses Bob's public key for the first (and only) phase
* of her version of the DH
* protocol.
* Before she can do so, she has to instantiate a DH public key
* from Bob's encoded key material.
*/
KeyFactory aliceKeyFac = KeyFactory.getInstance("DH");
x509KeySpec = new X509EncodedKeySpec(bobPubKeyEnc);
PublicKey bobPubKey = aliceKeyFac.generatePublic(x509KeySpec);
System.out.println("ALICE: Execute PHASE1 ...");
aliceKeyAgree.doPhase(bobPubKey, true);
/*
* Bob uses Alice's public key for the first (and only) phase
* of his version of the DH
* protocol.
*/
System.out.println("BOB: Execute PHASE1 ...");
bobKeyAgree.doPhase(alicePubKey, true);
/*
* At this stage, both Alice and Bob have completed the DH key
* agreement protocol.
* Both generate the (same) shared secret.
*/
byte[] aliceSharedSecret = aliceKeyAgree.generateSecret();
int aliceLen = aliceSharedSecret.length;
byte[] bobSharedSecret = new byte[aliceLen];
int bobLen;
try {
// show example of what happens if you
// provide an output buffer that is too short
bobLen = bobKeyAgree.generateSecret(bobSharedSecret, 1);
} catch (ShortBufferException e) {
System.out.println(e.getMessage());
}
// provide output buffer of required size
bobLen = bobKeyAgree.generateSecret(bobSharedSecret, 0);
System.out.println("Alice secret: " + toHexString(aliceSharedSecret));
System.out.println("Bob secret: " + toHexString(bobSharedSecret));
if (!java.util.Arrays.equals(aliceSharedSecret, bobSharedSecret))
throw new Exception("Shared secrets differ");
System.out.println("Shared secrets are the same");
/*
* Now let's return the shared secret as a SecretKey object
* and use it for encryption. First, we generate SecretKeys for the
* "DES" algorithm (based on the raw shared secret data) and
* then we use DES in ECB mode
* as the encryption algorithm. DES in ECB mode does not require any
* parameters.
*
* Then we use DES in CBC mode, which requires an initialization
* vector (IV) parameter. In CBC mode, you need to initialize the
* Cipher object with an IV, which can be supplied using the
* javax.crypto.spec.IvParameterSpec class. Note that you have to use
* the same IV for encryption and decryption: If you use a different
* IV for decryption than you used for encryption, decryption will
* fail.
*
* NOTE: If you do not specify an IV when you initialize the
* Cipher object for encryption, the underlying implementation
* will generate a random one, which you have to retrieve using the
* javax.crypto.Cipher.getParameters() method, which returns an
* instance of java.security.AlgorithmParameters. You need to transfer
* the contents of that object (e.g., in encoded format, obtained via
* the AlgorithmParameters.getEncoded() method) to the party who will
* do the decryption. When initializing the Cipher for decryption,
* the (reinstantiated) AlgorithmParameters object must be passed to
* the Cipher.init() method.
*/
System.out.println("Return shared secret as SecretKey object ...");
// Bob
// NOTE: The call to bobKeyAgree.generateSecret above reset the key
// agreement object, so we call doPhase again prior to another
// generateSecret call
bobKeyAgree.doPhase(alicePubKey, true);
SecretKey bobDesKey = bobKeyAgree.generateSecret("DES");
// Alice
// NOTE: The call to aliceKeyAgree.generateSecret above reset the key
// agreement object, so we call doPhase again prior to another
// generateSecret call
aliceKeyAgree.doPhase(bobPubKey, true);
SecretKey aliceDesKey = aliceKeyAgree.generateSecret("DES");
/*
* Bob encrypts, using DES in ECB mode
*/
Cipher bobCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
bobCipher.init(Cipher.ENCRYPT_MODE, bobDesKey);
byte[] cleartext = "This is just an example".getBytes();
byte[] ciphertext = bobCipher.doFinal(cleartext);
/*
* Alice decrypts, using DES in ECB mode
*/
Cipher aliceCipher = Cipher.getInstance("DES/ECB/PKCS5Padding");
aliceCipher.init(Cipher.DECRYPT_MODE, aliceDesKey);
byte[] recovered = aliceCipher.doFinal(ciphertext);
if (!java.util.Arrays.equals(cleartext, recovered))
throw new Exception("DES in CBC mode recovered text is " + "different from cleartext");
System.out.println("DES in ECB mode recovered text is " + "same as cleartext");
/*
* Bob encrypts, using DES in CBC mode
*/
bobCipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
bobCipher.init(Cipher.ENCRYPT_MODE, bobDesKey);
cleartext = "This is just an example".getBytes();
ciphertext = bobCipher.doFinal(cleartext);
// Retrieve the parameter that was used, and transfer it to Alice in
// encoded format
byte[] encodedParams = bobCipher.getParameters().getEncoded();
/*
* Alice decrypts, using DES in CBC mode
*/
// Instantiate AlgorithmParameters object from parameter encoding
// obtained from Bob
AlgorithmParameters params = AlgorithmParameters.getInstance("DES");
params.init(encodedParams);
aliceCipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
aliceCipher.init(Cipher.DECRYPT_MODE, aliceDesKey, params);
recovered = aliceCipher.doFinal(ciphertext);
if (!java.util.Arrays.equals(cleartext, recovered))
throw new Exception("DES in CBC mode recovered text is " + "different from cleartext");
System.out.println("DES in CBC mode recovered text is " + "same as cleartext");
}