Java/Security/File Secure IO

Basic IO example using SHA1

   <source lang="java">

import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.security.DigestInputStream; import java.security.DigestOutputStream; import java.security.MessageDigest; import java.security.Security; import org.bouncycastle.jce.provider.BouncyCastleProvider; /**

* Basic IO example using SHA1
*/

public class MainClass {

 public static void main(String[] args) throws Exception {
   Security.addProvider(new BouncyCastleProvider());        
   byte[] input = "www.jexp.ru".getBytes();
   System.out.println("input     : " + new String(input));    
   MessageDigest hash = MessageDigest.getInstance("SHA1");
   ByteArrayInputStream byteArrayInputStream = new ByteArrayInputStream(input);
   DigestInputStream digestInputStream = new DigestInputStream(byteArrayInputStream, hash);
   ByteArrayOutputStream byteArrayOutputStream = new ByteArrayOutputStream();
   int ch;
   while ((ch = digestInputStream.read()) >= 0) {
     byteArrayOutputStream.write(ch);
   }
   byte[] newInput = byteArrayOutputStream.toByteArray();
   System.out.println("in digest : " + new String(digestInputStream.getMessageDigest().digest()));
   byteArrayOutputStream = new ByteArrayOutputStream();
   DigestOutputStream digestOutputStream = new DigestOutputStream(byteArrayOutputStream, hash);
   digestOutputStream.write(newInput);
   digestOutputStream.close();
   System.out.println("out digest: " + new String(digestOutputStream.getMessageDigest().digest()));
 }

}

      </source>
   
  
 
  

Basic IO example with CTR using AES

   <source lang="java">

import java.io.ByteArrayInputStream; import java.io.ByteArrayOutputStream; import java.security.Security; import javax.crypto.Cipher; import javax.crypto.CipherInputStream; import javax.crypto.CipherOutputStream; import javax.crypto.spec.IvParameterSpec; import javax.crypto.spec.SecretKeySpec; /**

* Basic IO example with CTR using AES
*/

public class MainClass {

 public static void main(String[] args) throws Exception {
   Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());        
   byte[] input = "www.jexp.ru".getBytes();
   byte[] keyBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09,
       0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17 };
   byte[] ivBytes = new byte[] { 0x00, 0x01, 0x02, 0x03, 0x00, 0x01, 0x02, 0x03, 0x00, 0x00, 0x00,
       0x00, 0x00, 0x00, 0x00, 0x01 };
   SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
   IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
   Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding", "BC");
   System.out.println("input : " + new String(input));
   // encryption pass
   cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);
   ByteArrayInputStream bIn = new ByteArrayInputStream(input);
   CipherInputStream cIn = new CipherInputStream(bIn, cipher);
   ByteArrayOutputStream bOut = new ByteArrayOutputStream();
   int ch;
   while ((ch = cIn.read()) >= 0) {
     bOut.write(ch);
   }
   byte[] cipherText = bOut.toByteArray();
   System.out.println("cipher: " + new String(cipherText));
   // decryption pass
   cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
   bOut = new ByteArrayOutputStream();
   CipherOutputStream cOut = new CipherOutputStream(bOut, cipher);
   cOut.write(cipherText);
   cOut.close();
   System.out.println("plain : " + new String(bOut.toByteArray()));
 }

}

      </source>
   
  
 
  

DES Crypter And Decryper File

   <source lang="java">

import java.io.FileInputStream; import java.io.FileOutputStream; import java.io.InputStream; import java.io.OutputStream; import java.security.Security; 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 MainClass {

 static Cipher m_encrypter;
 static Cipher m_decrypter;
 public static void main(String args[]) throws Exception {
   Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
   SecretKey key = KeyGenerator.getInstance("DES").generateKey();
   // for CBC; must be 8 bytes
   byte[] initVector = new byte[] { 0x10, 0x10, 0x01, 0x04, 0x01, 0x01, 0x01, 0x02 };
   AlgorithmParameterSpec algParamSpec = new IvParameterSpec(initVector);
   Cipher m_encrypter = Cipher.getInstance("DES/CBC/PKCS5Padding");
   Cipher m_decrypter = Cipher.getInstance("DES/CBC/PKCS5Padding");
   m_encrypter.init(Cipher.ENCRYPT_MODE, key, algParamSpec);
   m_decrypter.init(Cipher.DECRYPT_MODE, key, algParamSpec);
   FileInputStream fis = new FileInputStream("cipherTest.in");
   FileOutputStream fos = new FileOutputStream("cipherTest.out");
   int dataInputSize = fis.available();
   byte[] inputBytes = new byte[dataInputSize];
   fis.read(inputBytes);
   write(inputBytes, fos);
   fos.flush();
   fis.close();
   fos.close();
   String inputFileAsString = new String(inputBytes);
   System.out.println("INPUT FILE CONTENTS\n" + inputFileAsString + "\n");
   System.out.println("File encrypted and saved to disk\n");
   fis = new FileInputStream("cipherTest.out");
   byte[] decrypted = new byte[dataInputSize];
   read(decrypted, fis);
   fis.close();
   String decryptedAsString = new String(decrypted);
   System.out.println("DECRYPTED FILE:\n" + decryptedAsString + "\n");
 }
 public static void write(byte[] bytes, OutputStream out) throws Exception {
   CipherOutputStream cos = new CipherOutputStream(out, m_encrypter);
   cos.write(bytes, 0, bytes.length);
   cos.close();
 }
 public static void read(byte[] bytes, InputStream in) throws Exception {
   CipherInputStream cis = new CipherInputStream(in, m_decrypter);
   int pos = 0, intValue;
   while ((intValue = cis.read()) != -1) {
     bytes[pos] = (byte) intValue;
     pos++;
   }
 }

}

      </source>