This is an example of how to encrypt data using the DES algorithm in CTR mode. Doing data encryption with the Data Encryption Standard algorithm, in CTR mode implies that you should:
- Create a byte array to be used as initial password to be encrypted, a byte array to be used as a key and a a byte array to be used as initialization vector.
- Create a new SecretKeySpec for the DES algorithm.
- Create a new IvParameterSpec, using the initialization vector byte array. Create a new Cipher for the “DES/CTR/NoPadding” transformation, using an
org.bouncycastle.jce.provider.BouncyCastleProvider(), with thegetInstance(String transformation, String provider)API method. - Initialize the cipher in encryption mode using the key and iv specs created above, with the
init(int opmode, Key key, AlgorithmParameterSpec params)API method. - Do the encryption of the initial byte array password, with
update(byte[] input, int inputOffset, int inputLen, byte[] output, int outputOffset)anddoFinal(byte[] output, int outputOffset)API methods of the Cipher. - Initialize the cipher again, this time in decryption mode and do the decryption,
as described in the code snippet below.
package com.javacodegeeks.snippets.core;
import java.security.Security;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
public class Main {
public static void main(String[] args) throws Exception {
Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
byte[] pass = "www.javacodegeeks.com".getBytes();
byte[] sKey = new byte[]{0x01, 0x23, 0x45, 0x67, (byte) 0x89, (byte) 0xab, (byte) 0xcd,
(byte) 0xef};
byte[] initializationVector = new byte[]{0x00, 0x01, 0x02, 0x03, 0x00, 0x00, 0x00, 0x01};
SecretKeySpec key = new SecretKeySpec(sKey, "DES");
IvParameterSpec ivSpv = new IvParameterSpec(initializationVector);
Cipher c = Cipher.getInstance("DES/CTR/NoPadding", "BC");
System.out.println("input : " + new String(pass));
// encryption pass
c.init(Cipher.ENCRYPT_MODE, key, ivSpv);
byte[] encText = new byte;
int ctLen = c.update(pass, 0, pass.length, encText, 0);
ctLen += c.doFinal(encText, ctLen);
System.out.println("cipher: " + new String(encText).getBytes("UTF-8").toString() + " bytes: " + ctLen);
// decryption pass
c.init(Cipher.DECRYPT_MODE, key, ivSpv);
byte[] decrpt = new byte;
int ptLen = c.update(encText, 0, ctLen, decrpt, 0);
ptLen += c.doFinal(decrpt, ptLen);
System.out.println("plain : " + new String(decrpt) + " bytes: " + ptLen);
}
}
Output:
input : www.javacodegeeks.com
cipher: [B@4d63e95 bytes: 21
plain : www.javacodegeeks.com bytes: 21
This was an example of how to encrypt data using the DES algorithm in CTR mode in Java.
