/* Ejemplo de uso de funciones de resumen Hash
* carga el fichero que recibe como parametro y genera el resumen
*/
public static void main(String[] args) throws Exception {
// Comprobar argumentos
if (args.length != 1) {
mensajeAyuda();
System.exit(1);
}
/* Cargar "provider" (sólo si no se usa el que viene por defecto) */
Security.addProvider(new BouncyCastleProvider()); // Usa provider BC
/* Crear función resumen */
// MessageDigest messageDigest = MessageDigest.getInstance("MD5"); // Usa MD5
MessageDigest messageDigest = MessageDigest.getInstance("SHA-1"); // Usar SHA-1
/* Leer fichero de 1k en 1k y pasar fragmentos leidos a la funcion resumen */
byte[] buffer = new byte[1000];
int leidos = in.read(buffer, 0, 1000);
while (leidos != -1) {
messageDigest.update(buffer); // Pasa texto claro a la función resumen
leidos = in.read(buffer, 0, 1000);
}
in.close();
byte[] resumen = messageDigest.digest(); // Completar el resumen
// Mostrar resumen
System.out.println("RESUMEN:");
mostrarBytes(resumen);
System.out.println();
}
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();
}
}