speedygonzalez
asked on
Create AES encryption key in java ensure Padding is used
hello,
I have created an AES128 encryption key using the following code.
Can you confirm if this will create the required padding "AES/CBC/PKCS5Padding" also?
I need to ensure padding is part of my key creation & not just a key being created without this.
Accoding to question Ahttps://www.experts-exchange.com/questions/26823316/Java-Base64Encoder-Class-What-is-the-Purpose-of-a-cipher.html it is included?
Thanks
I have created an AES128 encryption key using the following code.
Can you confirm if this will create the required padding "AES/CBC/PKCS5Padding" also?
I need to ensure padding is part of my key creation & not just a key being created without this.
Accoding to question Ahttps://www.experts-exchange.com/questions/26823316/Java-Base64Encoder-Class-What-is-the-Purpose-of-a-cipher.html it is included?
Thanks
import java.io.UnsupportedEncodingException;
import sun.misc.BASE64Encoder;
import java.security.Key;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.KeyGenerator;
import java.io.*;
public class SecretKeyBuilder {
public String keyVal;
public static void main(String[] args) {
SecretKeyBuilder keyBuild=new SecretKeyBuilder();
try {
System.out.println("String val = " + keyBuild.keyCreate());
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (NoSuchAlgorithmException f) {
f.printStackTrace();
} catch (IOException g) {
g.printStackTrace();
}
}
//create empty constructor
public SecretKeyBuilder(){
}
public String keyCreate() throws UnsupportedEncodingException, NoSuchAlgorithmException, IOException{
//Create the Secret Key
KeyGenerator generator = KeyGenerator.getInstance("AES");
generator.init(128); //Set to use AES 128
generator.init(new SecureRandom());
Key key = generator.generateKey();
byte[] keyBytes = key.getEncoded();
// Encode the key to Base64 Encryption
BASE64Encoder encoder = new BASE64Encoder();
String base64 = encoder.encode(keyBytes);
//Write the key to a properties file
FileWriter fstream = new FileWriter("test.properties");
BufferedWriter out = new BufferedWriter(fstream);
out.write(base64);
//Close the output stream
out.close();
return base64;
}
}ASKER CERTIFIED SOLUTION
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Of course, that code above should say DECRYPT_MODE for the dCipher.init()!
Apologies - I'm on a netbook with no development environment - so couldn't test the above! I'll recheck later to ensure it's ok.
Apologies - I'm on a netbook with no development environment - so couldn't test the above! I'll recheck later to ensure it's ok.
And of course, now I've tested it I've realised something else - for any cipher mode that's not ECB you will need to supply an initialisation vector (IV) to the decrypting cipher. Here's the corrected code - that does work!
public void testPadding() {
try {
// Obtain an AES key generator
KeyGenerator generator = KeyGenerator.getInstance("AES");
// Initialise this Key Generator to generate keys of strength 128bits
// and inform it to use the Java Provider supplied SecureRandom implementation
generator.init(128, new SecureRandom());
// Generate a new key
SecretKey key = generator.generateKey();
// Obtain a new cipher for encrypting
// Use the transformation which states
// : AES Encryption
// : Cipher Block Chaining mode
// : Optimal Asymmetric Encryption Padding with MD5 hashing and MGF1 masking
Cipher eCipher = Cipher
.getInstance("AES/CBC/PKCS5Padding");
// Do the same to get a cipher for decryption
Cipher dCipher = Cipher
.getInstance("AES/CBC/PKCS5Padding");
// Initialise these ciphers for encrypt/decrypt mode of operation
// and supply our newly generated key
eCipher.init(Cipher.ENCRYPT_MODE, key);
// For modes other than EBC we need to obtain the IV params
byte[] IV = eCipher.getIV ();
// These IV params are then used to initialise the decryption cipher
// Note: This IV can be prepended to the beginning of cipher text or
// passed via other means to a process that decrypts ciphertext
dCipher.init(Cipher.DECRYPT_MODE, key, new IvParameterSpec(IV));
// Test out the ciphers
String plainText = "Hello World";
// Convert string to bytes using UTF-8 charset
byte[] utf8 = plainText.getBytes("UTF8");
// Encrypt the bytes
byte[] encBytes = eCipher.doFinal(utf8);
// Decrypt them
byte[] decBytes = dCipher.doFinal(encBytes);
// Convert back to a string
String decText = new String(decBytes, "UTF8");
// Use JUnits assert tests to ensure things worked
assertEquals(plainText, decText);
} catch (NoSuchAlgorithmException nsae) {
fail(nsae.getMessage());
} catch (NoSuchPaddingException nspe) {
fail(nspe.getMessage());
} catch (InvalidKeyException ike) {
fail(ike.getMessage());
} catch (UnsupportedEncodingException uee) {
fail(uee.getMessage());
} catch (IllegalBlockSizeException ibse) {
fail(ibse.getMessage());
} catch (BadPaddingException bpe) {
fail(bpe.getMessage());
} catch (InvalidAlgorithmParameterException iape) {
fail(iape.getMessage());
}
}ASKER
Andypwhite, Apologies, I had not refreshed my page & only seen "objects" posting. I would have shared the points with you if I had seen yours also.
Thanks for the help & sorry for that. It's actually the second time I've done that now with a question!!!
Thanks for the help & sorry for that. It's actually the second time I've done that now with a question!!!
No problem :)
Sun JCE Reference
Here's an example I quickly knocked together:
Open in new window
*Note: You will need to determine what padding schemes are available based on the Java Provider you are using
*Note: I'm using JUnit test framework here.
Also - you should REALLY AVOID using the sun.misc.BASE64Encoder as it is undocumented, unsupported and, from my experience, unreliable with certain datasets. A quick google search should find a suitable alternative.