simplesymmetricpaddingexample.java

sip CMSEnvelopedData

package chapter2;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;


/**
 * Basic symmetric encryption example with padding
 */
public class SimpleSymmetricPaddingExample
{   
    public static void main(
        String[]    args)
        throws Exception
    {
        byte[]        input = 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[]        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 };
        
        SecretKeySpec key = new SecretKeySpec(keyBytes, "AES");

        Cipher        cipher = Cipher.getInstance("AES/ECB/PKCS7Padding", "BC");
        

        System.out.println("input : " + Utils.toHex(input));
        
        // encryption pass
        
        cipher.init(Cipher.ENCRYPT_MODE, key);
        
        byte[] cipherText = new byte[cipher.getOutputSize(input.length)];

        int ctLength = cipher.update(input, 0, input.length, cipherText, 0);
        
        ctLength += cipher.doFinal(cipherText, ctLength);
        
        System.out.println("cipher: " + Utils.toHex(cipherText) + " bytes: " + ctLength);
        
        // decryption pass
        
        cipher.init(Cipher.DECRYPT_MODE, key);
        
        byte[] plainText = new byte[cipher.getOutputSize(ctLength)];

        int ptLength = cipher.update(cipherText, 0, ctLength, plainText, 0);
        
        ptLength += cipher.doFinal(plainText, ptLength);
        
        System.out.println("plain : " + Utils.toHex(plainText) + " bytes: " + ptLength);
    }
}