Encrypting with DES Using a Pass Phrase - Java Security

Java examples for Security:DES

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Description

Encrypting with DES Using a Pass Phrase

Demo Code


import java.io.UnsupportedEncodingException;
import java.security.spec.AlgorithmParameterSpec;
import java.security.spec.KeySpec;

import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;

public class Main {
  public static void main(String[] argv) {
    // Here is an example that uses the class
    try {/* w w w .j a v  a 2s .com*/
      // Create encrypter/decrypter class
      DesEncrypter encrypter = new DesEncrypter("My Pass Phrase!");

      // Encrypt
      String encrypted = encrypter.encrypt("Don't tell anybody!");

      // Decrypt
      String decrypted = encrypter.decrypt(encrypted);
    } catch (Exception e) {
    }
  }
}

class DesEncrypter {
  Cipher ecipher;
  Cipher dcipher;

  // 8-byte Salt
  byte[] salt = { (byte) 0xA9, (byte) 0x9B, (byte) 0xC8, (byte) 0x32,
      (byte) 0x56, (byte) 0x35, (byte) 0xE3, (byte) 0x03 };

  // Iteration count
  int iterationCount = 19;

  DesEncrypter(String passPhrase) {
    try {
      // Create the key
      KeySpec keySpec = new PBEKeySpec(passPhrase.toCharArray(), salt,
          iterationCount);
      SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES")
          .generateSecret(keySpec);
      ecipher = Cipher.getInstance(key.getAlgorithm());
      dcipher = Cipher.getInstance(key.getAlgorithm());

      // Prepare the parameter to the ciphers
      AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt,
          iterationCount);

      // Create the ciphers
      ecipher.init(Cipher.ENCRYPT_MODE, key, paramSpec);
      dcipher.init(Cipher.DECRYPT_MODE, key, paramSpec);
    } catch (java.security.InvalidAlgorithmParameterException e) {
    } catch (java.security.spec.InvalidKeySpecException e) {
    } catch (javax.crypto.NoSuchPaddingException e) {
    } catch (java.security.NoSuchAlgorithmException e) {
    } catch (java.security.InvalidKeyException e) {
    }
  }

  public String encrypt(String str) {
    try {
      // Encode the string into bytes using utf-8
      byte[] utf8 = str.getBytes("UTF8");

      // Encrypt
      byte[] enc = ecipher.doFinal(utf8);

      // Encode bytes to base64 to get a string
      return new sun.misc.BASE64Encoder().encode(enc);
    } catch (Exception e) {
    }
    return null;
  }

  public String decrypt(String str) {
    try {
      // Decode base64 to get bytes
      byte[] dec = new sun.misc.BASE64Decoder().decodeBuffer(str);

      // Decrypt
      byte[] utf8 = dcipher.doFinal(dec);

      // Decode using utf-8
      return new String(utf8, "UTF8");
    } catch (Exception e) {
    }
    return null;
  }
}

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