Using the KeyGenerator class and showing how to create a SecretKeySpec from an encoded key
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);
}
}
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