AES SecretKeyFactory not available - error with secretKey file

[Kevin P Smith]

Hi guys,

I have the following code for generating and reading a secretKey file which I use for encode/decode.

Just wondering if anyone could shed any light onto why I get the

java.security.NoSuchAlgorithmException: AES SecretKeyFactory not available
	at javax.crypto.SecretKeyFactory.<init>(DashoA13*..)
	at javax.crypto.SecretKeyFactory.getInstance(DashoA13*..)

Error when running my encryption/decryption code.

below is the code for generating the key and reading the key and encryption/decryption...

public final class SecretKeyUtil {
	
	public static String SECRET_KEY_DAT = "C:/development/secretkey_aes256.dat";
	public static String SECRET_KEY_TYPE = "AES";
	public static int KEYSIZE = 256;
	public static String UTF_8 = "UTF8";
	
	public static void main(String args[]) {
		try {
			SecretKeyUtil.generateSecretKey();
			System.out.println("Key file created!");
		} catch (Exception ex) {
			ex.printStackTrace();
		}
	}
	
	public static void generateSecretKey() throws NoSuchAlgorithmException, InvalidKeySpecException, IOException {
		KeyGenerator keyGen = KeyGenerator.getInstance(SECRET_KEY_TYPE);
		keyGen.init(KEYSIZE);
		SecretKey secretKey = keyGen.generateKey();
		byte[] secretKeyBytes = secretKey.getEncoded();

		//SecretKeyFactory keyfactory = SecretKeyFactory.getInstance(SECRET_KEY_TYPE);
		//DESedeKeySpec keyspec = (DESedeKeySpec) keyfactory.getKeySpec(key, DESedeKeySpec.class);
		SecretKeySpec key = new SecretKeySpec(secretKeyBytes, SECRET_KEY_TYPE);
		//byte[] rawkey = key.getKey();
		 byte[] encoded = key.getEncoded();

		// Write the raw key to the file
		File keyfile = new File(SECRET_KEY_DAT);
		FileOutputStream fos = new FileOutputStream(keyfile);
		fos.write(encoded);
		fos.close();
	}
	
	public static SecretKey getSecretkey() throws NoSuchAlgorithmException,
			InvalidKeySpecException, IOException, InvalidKeyException {
		
		boolean exists = new File(SECRET_KEY_DAT).exists();
		if (!exists) {
			SecretKeyUtil.generateSecretKey();
		}
		return SecretKeyUtil.readSecretKey();
	}

	public static SecretKey readSecretKey() throws IOException, NoSuchAlgorithmException, InvalidKeyException,
			InvalidKeySpecException {
		// Read the raw bytes from the keyfile
		File keyfile = new File(SECRET_KEY_DAT);
		DataInputStream input = new DataInputStream(new FileInputStream(keyfile));
		byte[] rawkey = new byte[(int) keyfile.length()];
		input.readFully(rawkey);
		input.close();

		// Convert the raw bytes to a secret key like this
		SecretKeySpec keyspec = new SecretKeySpec(rawkey,SECRET_KEY_TYPE);
		SecretKeyFactory keyfactory = SecretKeyFactory.getInstance(SECRET_KEY_TYPE);
		SecretKey key = keyfactory.generateSecret(keyspec);
		return key;
	}
}

Encryption

	public static String encrypter(String value) {
		try {
			SecretKey secretKey = SecretKeyUtil.getSecretkey();
			Cipher cipher = Cipher.getInstance(SecretKeyUtil.SECRET_KEY_TYPE);
			cipher.init(Cipher.ENCRYPT_MODE, secretKey);
			byte[] bytes = value.getBytes();
			byte[] bytesEncrypted = cipher.doFinal(bytes);
			return new String(bytesEncrypted);
		} catch (Exception ex) {
			ex.printStackTrace();
			return value;
		}
	}

Decryption

	public static String decrypter(String value) {
		try {
			SecretKey secretKey = SecretKeyUtil.getSecretkey();
			Cipher cipher = Cipher.getInstance(SecretKeyUtil.SECRET_KEY_TYPE);
			cipher.init(Cipher.DECRYPT_MODE, secretKey);
			byte[] bytes = value.getBytes();
			byte[] bytesDecrypted = cipher.doFinal(bytes);
			return new String(bytesDecrypted);
		} catch (Exception ex) {
			ex.printStackTrace();
			return value;
		}
	}

Cheers in advance

KS

[Richard Tookey]

It seems that the AES secret key factory is missing in 1.7 (a known bug ). Since SecretKeySpec extends SecretKey this is easy to get round

 public static SecretKey readSecretKey() throws IOException, NoSuchAlgorithmException, InvalidKeyException,  
            InvalidKeySpecException {  
        // Read the raw bytes from the keyfile  
        File keyfile = new File(SECRET_KEY_DAT);  
        DataInputStream input = new DataInputStream(new FileInputStream(keyfile));  
        byte[] rawkey = new byte[(int) keyfile.length()];  
        input.readFully(rawkey);  
        input.close();  
  
        // Convert the raw bytes to a secret key like this  
        SecretKeySpec keyspec = new SecretKeySpec(rawkey,SECRET_KEY_TYPE);  
        return keyspec;  
    }  

[Kevin P Smith]

Fantastic, cool & cheers all rolled into one!

[Richard Tookey]

Kevin P Smith wrote:Fantastic, cool & cheers all rolled into one!

Of course you do realize that your Cipher construction defaults to using ECB block mode which is generally considered insecure since it allows splicing of ciphertext to produce valid forged cleartext. You should really use one of the feedback block modes such as CBC.