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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * particular file as subject to the "Classpath" exception as provided
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 * 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).
 *
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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-SHA1 algorithm.

Author:Jan Luehe
/**
 * This class generates a secret key for use with the HMAC-SHA1 algorithm.
 *
 * @author Jan Luehe
 *
 */

public final class HmacSHA1KeyGenerator extends KeyGeneratorSpi {

    private SecureRandom random = null;
    private int keysize = 64; // default keysize (in number of bytes)

    
Empty constructor

/**
     * Empty constructor
     */
    public HmacSHA1KeyGenerator() {
    }

    
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
            ("HMAC-SHA1 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) {
        this.keysize = (keysize+7) / 8;
        this.engineInit(random);
    }

    
Generates an HMAC-SHA1 key.

Returns:the new HMAC-SHA1 key
/**
     * Generates an HMAC-SHA1 key.
     *
     * @return the new HMAC-SHA1 key
     */
    protected SecretKey engineGenerateKey() {
        if (this.random == null) {
            this.random = SunJCE.getRandom();
        }

        byte[] keyBytes = new byte[this.keysize];
        this.random.nextBytes(keyBytes);

        return new SecretKeySpec(keyBytes, "HmacSHA1");
    }
}