public byte[] getE() throws Exception {
if (e == null) {
DHParameterSpec dhSkipParamSpec = new DHParameterSpec(p, g);
myKpairGen.initialize(dhSkipParamSpec);
KeyPair myKpair = myKpairGen.generateKeyPair();
myKeyAgree.init(myKpair.getPrivate());
// BigInteger x=((javax.crypto.interfaces.DHPrivateKey)(myKpair.getPrivate())).getX();
byte[] myPubKeyEnc = myKpair.getPublic().getEncoded();
e = ((javax.crypto.interfaces.DHPublicKey) (myKpair.getPublic())).getY();
e_array = e.toByteArray();
}
return e_array;
}
public void run() {
try {
ObjectInputStream ois = new ObjectInputStream(s.getInputStream());
ObjectOutputStream oos = new ObjectOutputStream(s.getOutputStream());
BigInteger bg = dhSpec.getG();
BigInteger bp = dhSpec.getP();
oos.writeObject(bg);
oos.writeObject(bp);
KeyPairGenerator kpg = KeyPairGenerator.getInstance("DH");
kpg.initialize(1024);
KeyPair kpa = (KeyPair) ois.readObject();
KeyAgreement dh = KeyAgreement.getInstance("DH");
KeyPair kp = kpg.generateKeyPair();
oos.writeObject(kp);
dh.init(kp.getPrivate());
Key pk = dh.doPhase(kpa.getPublic(), true);
MessageDigest sha256 = MessageDigest.getInstance("SHA-256");
byte[] rawbits = sha256.digest(dh.generateSecret());
Cipher c = Cipher.getInstance(CIPHER_MODE);
SecretKey key = new SecretKeySpec(rawbits, 0, 16, "AES");
byte ivbits[] = (byte[]) ois.readObject();
IvParameterSpec iv = new IvParameterSpec(ivbits);
c.init(Cipher.DECRYPT_MODE, key, iv);
Mac m = Mac.getInstance("HmacSHA1");
SecretKey mackey = new SecretKeySpec(rawbits, 16, 16, "HmacSHA1");
m.init(mackey);
byte ciphertext[], cleartext[], mac[];
try {
while (true) {
ciphertext = (byte[]) ois.readObject();
mac = (byte[]) ois.readObject();
if (Arrays.equals(mac, m.doFinal(ciphertext))) {
cleartext = c.update(ciphertext);
System.out.println(ct + " : " + new String(cleartext, "UTF-8"));
} else {
// System.exit(1);
System.out.println(ct + "error");
}
}
} catch (EOFException e) {
cleartext = c.doFinal();
System.out.println(ct + " : " + new String(cleartext, "UTF-8"));
System.out.println("[" + ct + "]");
} finally {
if (ois != null) ois.close();
if (oos != null) oos.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* Creates a file server. Uses aConnectedSocket to create input/output stream readers to
* communicate with a client.
*
* @param aConnectedSocket Socket through which to communicated with a client.
*/
public FileServer(Socket aConnectedSocket) throws IOException, NoSuchAlgorithmException {
connectedSocket = aConnectedSocket;
// Set up input/output streams
inFromClient = new BufferedReader(new InputStreamReader(connectedSocket.getInputStream()));
outToClient = new DataOutputStream(connectedSocket.getOutputStream());
// generate keys
KeyPair keyPair = KeyPairGenerator.getInstance("RSA").generateKeyPair();
privateKey = keyPair.getPrivate();
publicKey = keyPair.getPublic();
}
public static void main(String[] args) throws Exception {
//
// verifica args e recebe o texto plano
if (args.length != 1) {
System.err.println("Usage: java DigitalSignatureExample text");
System.exit(1);
}
byte[] plainText = args[0].getBytes("UTF8");
//
// gera o par de chaves RSA
System.out.println("\nStart generating RSA key");
KeyPairGenerator keyGen = KeyPairGenerator.getInstance("RSA");
keyGen.initialize(1024);
KeyPair key = keyGen.generateKeyPair();
System.out.println("Finish generating RSA key");
//
// define um objeto signature para utilizar MD5 e RSA
// e assina o texto plano com a chave privada,
// o provider utilizado tambem eh impresso
Signature sig = Signature.getInstance("MD5WithRSA");
sig.initSign(key.getPrivate());
sig.update(plainText);
byte[] signature = sig.sign();
System.out.println(sig.getProvider().getInfo());
System.out.println("\nSignature:");
// converte o signature para hexadecimal
StringBuffer buf = new StringBuffer();
for (int i = 0; i < signature.length; i++) {
String hex = Integer.toHexString(0x0100 + (signature[i] & 0x00FF)).substring(1);
buf.append((hex.length() < 2 ? "0" : "") + hex);
}
// imprime o signature em hexadecimal
System.out.println(buf.toString());
//
// verifica a assinatura com a chave publica
System.out.println("\nStart signature verification");
sig.initVerify(key.getPublic());
sig.update(plainText);
try {
if (sig.verify(signature)) {
System.out.println("Signature verified");
} else System.out.println("Signature failed");
} catch (SignatureException se) {
System.out.println("Singature failed");
}
}
public static void main(String[] args) throws Exception {
// prompt user to enter a port number
System.out.print("Enter the port number: ");
Scanner scan = new Scanner(System.in);
int port = scan.nextInt();
scan.nextLine();
System.out.print("Enter the host name: ");
String hostName = scan.nextLine();
// Initialize a key pair generator with the SKIP parameters we sepcified, and genrating a pair
// This will take a while: 5...15 seconrds
System.out.println("Generating a Diffie-Hellman keypair: ");
KeyPairGenerator kpg = KeyPairGenerator.getInstance("DH");
kpg.initialize(PARAMETER_SPEC);
KeyPair keyPair = kpg.genKeyPair();
System.out.println("key pair has been made...");
// one the key pair has been generated, we want to listen on
// a given port for a connection to come in
// once we get a connection, we will get two streams, One for input
// and one for output
// open a port and wait for a connection
ServerSocket ss = new ServerSocket(port);
System.out.println("Listeining on port " + port + " ...");
Socket socket = ss.accept();
// use to output and input primitive data type
DataOutputStream out = new DataOutputStream(socket.getOutputStream());
// next thing to do is send our public key and receive client's
// this corresponds to server step 3 and step 4 in the diagram
System.out.println("Sending my public key...");
byte[] keyBytes = keyPair.getPublic().getEncoded();
out.writeInt(keyBytes.length);
out.write(keyBytes);
System.out.println("Server public key bytes: " + CryptoUtils.toHex(keyBytes));
// receive the client's public key
System.out.println("Receiving client's public key...");
DataInputStream in = new DataInputStream(socket.getInputStream());
keyBytes = new byte[in.readInt()];
in.readFully(keyBytes);
// create client's public key
KeyFactory kf = KeyFactory.getInstance("DH");
X509EncodedKeySpec x509Spec = new X509EncodedKeySpec(keyBytes);
PublicKey clientPublicKey = kf.generatePublic(x509Spec);
// print out client's public key bytes
System.out.println(
"Client public key bytes: " + CryptoUtils.toHex(clientPublicKey.getEncoded()));
// we can now use the client's public key and
// our own private key to perform the key agreement
System.out.println("Performing the key agreement ... ");
KeyAgreement ka = KeyAgreement.getInstance("DH");
ka.init(keyPair.getPrivate());
ka.doPhase(clientPublicKey, true);
// in a chat application, each character is sendt over the wire, separetly encrypted,
// Instead of using ECB, we are goin to use CFB, with a block size of 8 bits(1byte)
// to send each character. We will encrypt the same character in a different way
// each time. But in order to use CFB8, we need an IVof 8 bytes. We will create
// that IV randomly and and send it to the client. It doesn't matter if somoene
// eavesdrops on the IV when it is sent over the wire. it's not sensitive info
// creating the IV and sending it corresponds to step 6 and 7
byte[] iv = new byte[8];
SecureRandom sr = new SecureRandom();
sr.nextBytes(iv);
out.write(iv);
// we generate the secret byte array we share with the client and use it
// to create the session key (Step 8)
byte[] sessionKeyBytes = ka.generateSecret();
// create the session key
SecretKeyFactory skf = SecretKeyFactory.getInstance("DESede");
DESedeKeySpec DESedeSpec = new DESedeKeySpec(sessionKeyBytes);
SecretKey sessionKey = skf.generateSecret(DESedeSpec);
// printout session key bytes
System.out.println("Session key bytes: " + CryptoUtils.toHex(sessionKey.getEncoded()));
// now use tha that session key and IV to create a CipherInputStream. We will use them to read
// all character
// that are sent to us by the client
System.out.println("Creating the cipher stream ...");
Cipher decrypter = Cipher.getInstance("DESede/CFB8/NoPadding");
IvParameterSpec spec = new IvParameterSpec(iv);
decrypter.init(Cipher.DECRYPT_MODE, sessionKey, spec);
CipherInputStream cipherIn = new CipherInputStream(socket.getInputStream(), decrypter);
// we just keep reading the input and print int to the screen, until -1 sent over
int theCharacter = 0;
theCharacter = cipherIn.read();
while (theCharacter != -1) {
System.out.print((char) theCharacter);
theCharacter = cipherIn.read();
}
// once -1 is received we want to close up our stream and exit
cipherIn.close();
in.close();
out.close();
socket.close();
}
public static void main(String[] args) {
try {
if (args[0].equals("-genkey")) {
KeyPairGenerator pairgen = KeyPairGenerator.getInstance("RSA");
SecureRandom random = new SecureRandom();
pairgen.initialize(KEYSIZE, random);
KeyPair keyPair = pairgen.generateKeyPair();
ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream(args[1]));
out.writeObject(keyPair.getPublic());
out.close();
out = new ObjectOutputStream(new FileOutputStream(args[2]));
out.writeObject(keyPair.getPrivate());
out.close();
} else if (args[0].equals("-encrypt")) {
KeyGenerator keygen = KeyGenerator.getInstance("AES");
SecureRandom random = new SecureRandom();
keygen.init(random);
SecretKey key = keygen.generateKey();
// wrap with RSA public key
ObjectInputStream keyIn = new ObjectInputStream(new FileInputStream(args[3]));
Key publicKey = (Key) keyIn.readObject();
keyIn.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.WRAP_MODE, publicKey);
byte[] wrappedKey = cipher.wrap(key);
DataOutputStream out = new DataOutputStream(new FileOutputStream(args[2]));
out.writeInt(wrappedKey.length);
out.write(wrappedKey);
InputStream in = new FileInputStream(args[1]);
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.ENCRYPT_MODE, key);
crypt(in, out, cipher);
in.close();
out.close();
} else {
DataInputStream in = new DataInputStream(new FileInputStream(args[1]));
int length = in.readInt();
byte[] wrappedKey = new byte[length];
in.read(wrappedKey, 0, length);
// unwrap with RSA private key
ObjectInputStream keyIn = new ObjectInputStream(new FileInputStream(args[3]));
Key privateKey = (Key) keyIn.readObject();
keyIn.close();
Cipher cipher = Cipher.getInstance("RSA");
cipher.init(Cipher.UNWRAP_MODE, privateKey);
Key key = cipher.unwrap(wrappedKey, "AES", Cipher.SECRET_KEY);
OutputStream out = new FileOutputStream(args[2]);
cipher = Cipher.getInstance("AES");
cipher.init(Cipher.DECRYPT_MODE, key);
crypt(in, out, cipher);
in.close();
out.close();
}
} catch (IOException e) {
e.printStackTrace();
} catch (GeneralSecurityException e) {
e.printStackTrace();
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
}