AES Encryption/Decryption Interop for Java and C#

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Java Class.

Code:

package text.util;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;

import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

/**
* <p>Title: CipherUtil</p>
* <p>Description: Utility class for encrypt and decrypt string with AES algorithm, CBC mode, 128 bits</p>
* <p>Copyright: Copyright (c) 2014</p>
*
* @author psupawa@gmail.com
* @version 1.0.0
*/
public class CipherUtil {

   /**
    * For testing
    * @param args
    * @throws Exception
    */
   public static void main(String[] args) throws Exception {
       CipherUtil cu = new CipherUtil();
       String strToEncrypt = "Hello Java";
       System.out.println("String to encrypt : "+new String(strToEncrypt));
       byte[] encryptedBytes = cu.getEncryptedData(strToEncrypt.getBytes());
       System.out.println("Encrypted message : "+new String(Base64Util.encode(encryptedBytes)));
       System.out.println("Decrypted message : "+new String(cu.getDecryptedData(encryptedBytes)));
       
       // Decrypt from external encryption
       String encodedStrToDecrypt = "zpRWg0Y/S6ddBlUL4VuhuA==";
       System.out.println("String to decrypt : "+encodedStrToDecrypt);
       String input = Base64Util.decodeString(encodedStrToDecrypt);
       byte[] decryptedBytes = cu.getDecryptedData(input.getBytes());
       System.out.println("Decrypted message2 : "+new String(decryptedBytes));
   }

   // Declare variables
   private String padding = "ISO10126Padding";  
   private String keySpec = "thisIsAKey16bits";
   private String ivSpec = "hereA16bitIVspec";
   private byte[] keyBytes;
   private byte[] ivBytes;

   /**
    * Constructor
    */
   public CipherUtil() {
       this.keyBytes = keySpec.getBytes();
       this.ivBytes = ivSpec.getBytes();
   }

   /**
    * Constructor
    * @param keySpec
    * @param ivSpec
    * @throws Exception
    */
   public CipherUtil(String keySpec, String ivSpec) throws Exception {
       if (keySpec.length() == 16) {
          this.keySpec = keySpec;
          this.keyBytes = keySpec.getBytes();
       }
       else
           throw new Exception("Key spec length must be 16 bytes");
       if (ivSpec.length() == 16) {
           this.ivSpec = ivSpec;
           this.ivBytes = ivSpec.getBytes();
       }
       else
           throw new Exception("IV spec length must be 16 bytes");
   }

   /**
    * Encryption base
    * @param cipher
    * @param dataBytes
    * @return
    * @throws Exception
    */
   private byte[] encrypt(Cipher cipher, byte[] dataBytes) throws Exception{
       ByteArrayInputStream bIn = new ByteArrayInputStream(dataBytes);
       CipherInputStream cIn = new CipherInputStream(bIn, cipher);
       ByteArrayOutputStream bOut = new ByteArrayOutputStream();
       int ch;
       while ((ch = cIn.read()) >= 0) {
           bOut.write(ch);
       }
       return bOut.toByteArray();
   }

   /**
     * Decryption base
     * @param cipher
     * @param dataBytes
     * @return
     * @throws Exception
     */
   private byte[] decrypt(Cipher cipher, byte[] dataBytes) throws Exception{
       ByteArrayOutputStream bOut = new ByteArrayOutputStream();
       CipherOutputStream cOut = new CipherOutputStream(bOut, cipher);
       cOut.write(dataBytes);
       cOut.close();
       return bOut.toByteArray();    
   }
   
   /**
    * Get encryption mode
    * @return cipher encryption
    * @throws Exception
    */
   private Cipher getAESCBCEncryptor() throws Exception{
       SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
       IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
       Cipher cipher = Cipher.getInstance("AES/CBC/"+padding);
       cipher.init(Cipher.ENCRYPT_MODE, key, ivSpec);
       return cipher;
   }
   
   /**
    * Get decryption mode
    * @return cipher decryption
    * @throws Exception
    */
   private Cipher getAESCBCDecryptor() throws Exception{
       SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");
       IvParameterSpec ivSpec = new IvParameterSpec(ivBytes);
       Cipher cipher = Cipher.getInstance("AES/CBC/"+padding);
       cipher.init(Cipher.DECRYPT_MODE, key, ivSpec);
       return cipher;
   }

   /**
    * Get encryption data
    * @param messageBytes
    * @return byte array
    * @throws Exception
    */
   public byte[] getEncryptedData(byte[] messageBytes) throws Exception {
       Cipher cipher = getAESCBCEncryptor();
       return encrypt(cipher, messageBytes);
   }

   /**
    * Get encryption string
    * @param messageBytes
    * @return string
    * @throws Exception
    */
   public String getEncryptedString(byte[] messageBytes) throws Exception {
       return new String(Base64Util.encode(getEncryptedData(messageBytes)));
   }

   /**
    * Get decryption data
    * @param encryptedMessageBytes
    * @return byte array
    * @throws Exception
    */
   public byte[] getDecryptedData(byte[] encryptedMessageBytes) throws Exception {
       Cipher decipher = getAESCBCDecryptor();
       return decrypt(decipher, encryptedMessageBytes);
   }
   
   /**
    * Get decryption string
    * @param encryptedMessageBytes
    * @return string
    * @throws Exception
    */
   public String getDecryptedString(byte[] encryptedMessageBytes) throws Exception {
       return new String(getDecryptedData(encryptedMessageBytes));
   }
   
}


 
Example result from Java.

Code:

String to encrypt : Hello Java
Encrypted message : F6b73SkEneMlRQNSmtF4sA==
Decrypted message : Hello Java
String to decrypt : xmFcq22TBiFMWR+XuGZ2HQ==
Decrypted message2 : Hello C#


 
For C# example please goto forum, https://maithai.thai-forum.net/t5-topic