/*
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package com.sun.crypto.provider;
import java.security.SecureRandom;
import java.security.InvalidParameterException;
import java.security.InvalidAlgorithmParameterException;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.KeyGeneratorSpi;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
/**
* This class generates a secret key for use with the HMAC-MD5 algorithm.
*
* @author Jan Luehe
*
*/
public final class HmacMD5KeyGenerator extends KeyGeneratorSpi {
private SecureRandom random = null;
private int keysize = 64; // default keysize (in number of bytes)
/**
* Verify the SunJCE provider in the constructor.
*
* @exception SecurityException if fails to verify
* its own integrity
*/
public HmacMD5KeyGenerator() {
if (!SunJCE.verifySelfIntegrity(this.getClass())) {
throw new SecurityException("The SunJCE provider may have " +
"been tampered.");
}
}
/**
* 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.
*
* @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
("HMAC-MD5 key generation does not take any parameters");
}
/**
* 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) {
this.keysize = (keysize+7) / 8;
this.engineInit(random);
}
/**
* Generates an HMAC-MD5 key.
*
* @return the new HMAC-MD5 key
*/
protected SecretKey engineGenerateKey() {
if (this.random == null) {
this.random = SunJCE.RANDOM;
}
byte[] keyBytes = new byte[this.keysize];
this.random.nextBytes(keyBytes);
return new SecretKeySpec(keyBytes, "HmacMD5");
}
}