MainClass.java Source code

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Here is the source code for MainClass.java

Source

import java.security.Key;
import java.security.Security;

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

/**
 * Basic example using the KeyGenerator class and showing how to create a
 * SecretKeySpec from an encoded key.
 */
public class MainClass {
    public static void main(String[] args) throws Exception {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
        byte[] input = "www.java2s.com".getBytes();

        byte[] ivBytes = new byte[] { 0x00, 0x00, 0x00, 0x01, 0x04, 0x05, 0x06, 0x07, 0x00, 0x00, 0x00, 0x00, 0x00,
                0x00, 0x00, 0x01 };

        Cipher cipher = Cipher.getInstance("AES/CTR/NoPadding", "BC");
        KeyGenerator generator = KeyGenerator.getInstance("AES", "BC");

        generator.init(192);

        Key encryptionKey = generator.generateKey();

        System.out.println("key   : " + Utils.toHex(encryptionKey.getEncoded()));
        System.out.println("input : " + new String(input));

        // encryption pass
        cipher.init(Cipher.ENCRYPT_MODE, encryptionKey, new IvParameterSpec(ivBytes));
        byte[] cipherText = new byte[cipher.getOutputSize(input.length)];
        int ctLength = cipher.update(input, 0, input.length, cipherText, 0);
        ctLength += cipher.doFinal(cipherText, ctLength);

        // decryption pass
        Key decryptionKey = new SecretKeySpec(encryptionKey.getEncoded(), encryptionKey.getAlgorithm());
        cipher.init(Cipher.DECRYPT_MODE, decryptionKey, new IvParameterSpec(ivBytes));
        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 : " + new String(plainText) + " bytes: " + ptLength);
    }
}

class Utils {
    private static String digits = "0123456789abcdef";

    /**
     * Return length many bytes of the passed in byte array as a hex string.
     * 
     * @param data the bytes to be converted.
     * @param length the number of bytes in the data block to be converted.
     * @return a hex representation of length bytes of data.
     */
    public static String toHex(byte[] data, int length) {
        StringBuffer buf = new StringBuffer();

        for (int i = 0; i != length; i++) {
            int v = data[i] & 0xff;

            buf.append(digits.charAt(v >> 4));
            buf.append(digits.charAt(v & 0xf));
        }

        return buf.toString();
    }

    /**
     * Return the passed in byte array as a hex string.
     * 
     * @param data the bytes to be converted.
     * @return a hex representation of data.
     */
    public static String toHex(byte[] data) {
        return toHex(data, data.length);
    }
}