Encrypting a File or Stream with DES - Java Security

Java examples for Security:DES

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Description

Encrypting a File or Stream with DES

Demo Code


import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import javax.crypto.spec.IvParameterSpec;

public class Main {
  public void main(String[] argv) {
    try {//from w ww. j  av  a  2  s . com
      SecretKey key = KeyGenerator.getInstance("DES").generateKey();

      // Create encrypter/decrypter class
      DesEncrypter encrypter = new DesEncrypter(key);

      // Encrypt
      encrypter.encrypt(new FileInputStream("cleartext1"),
          new FileOutputStream("ciphertext"));

      // Decrypt
      encrypter.decrypt(new FileInputStream("ciphertext"),
          new FileOutputStream("cleartext2"));
    } catch (Exception e) {
    }
  }
}

class DesEncrypter {
  Cipher ecipher;
  Cipher dcipher;

  DesEncrypter(SecretKey key) {
    byte[] iv = new byte[] { (byte) 0x8E, 0x12, 0x39, (byte) 0x9C, 0x07, 0x72,
        0x6F, 0x5A };
    AlgorithmParameterSpec paramSpec = new IvParameterSpec(iv);
    try {
      ecipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
      dcipher = Cipher.getInstance("DES/CBC/PKCS5Padding");

      // CBC requires an initialization vector
      ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
      dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
    } catch (java.security.InvalidAlgorithmParameterException e) {
    } catch (javax.crypto.NoSuchPaddingException e) {
    } catch (java.security.NoSuchAlgorithmException e) {
    } catch (java.security.InvalidKeyException e) {
    }
  }

  byte[] buf = new byte[1024];

  public void encrypt(InputStream in, OutputStream out) {
    try {
      out = new CipherOutputStream(out, ecipher);

      int numRead = 0;
      while ((numRead = in.read(buf)) >= 0) {
        out.write(buf, 0, numRead);
      }
      out.close();
    } catch (java.io.IOException e) {
    }
  }

  public void decrypt(InputStream in, OutputStream out) {
    try {
      in = new CipherInputStream(in, dcipher);

      int numRead = 0;
      while ((numRead = in.read(buf)) >= 0) {
        out.write(buf, 0, numRead);
      }
      out.close();
    } catch (java.io.IOException e) {
    }
  }
}

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