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package com.sun.crypto.provider;

import java.security.SecureRandom;
import java.security.InvalidParameterException;
import java.security.InvalidAlgorithmParameterException;
import java.security.InvalidKeyException;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.KeyGeneratorSpi;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;


This class generates a AES key.
Author:Valerie Peng
/** * This class generates a AES key. * * @author Valerie Peng * */
public final class AESKeyGenerator extends KeyGeneratorSpi { private SecureRandom random = null; private int keySize = 16; // default keysize (in number of bytes)
Empty constructor.
/** * Empty constructor. */
public AESKeyGenerator() { }
Initializes this key generator.
Params:
  • random – the source of randomness for this generator
/** * Initializes this key generator. * * @param random the source of randomness for this generator */
protected void engineInit(SecureRandom random) { this.random = random; }
Initializes this key generator with the specified parameter set and a user-provided source of randomness.
Params:
  • params – the key generation parameters
  • random – the source of randomness for this key generator
Throws:
/** * Initializes this key generator with the specified parameter * set and a user-provided source of randomness. * * @param params the key generation parameters * @param random the source of randomness for this key generator * * @exception InvalidAlgorithmParameterException if <code>params</code> is * inappropriate for this key generator */
protected void engineInit(AlgorithmParameterSpec params, SecureRandom random) throws InvalidAlgorithmParameterException { throw new InvalidAlgorithmParameterException ("AES key generation does not take any parameters"); }
Initializes this key generator for a certain keysize, using the given source of randomness.
Params:
  • keysize – the keysize. This is an algorithm-specific metric specified in number of bits.
  • random – the source of randomness for this key generator
/** * Initializes this key generator for a certain keysize, using the given * source of randomness. * * @param keysize the keysize. This is an algorithm-specific * metric specified in number of bits. * @param random the source of randomness for this key generator */
protected void engineInit(int keysize, SecureRandom random) { if (((keysize % 8) != 0) || (!AESCrypt.isKeySizeValid(keysize/8))) { throw new InvalidParameterException ("Wrong keysize: must be equal to 128, 192 or 256"); } this.keySize = keysize/8; this.engineInit(random); }
Generates the AES key.
Returns:the new AES key
/** * Generates the AES key. * * @return the new AES key */
protected SecretKey engineGenerateKey() { SecretKeySpec aesKey = null; if (this.random == null) { this.random = SunJCE.RANDOM; } byte[] keyBytes = new byte[keySize]; this.random.nextBytes(keyBytes); aesKey = new SecretKeySpec(keyBytes, "AES"); return aesKey; } }