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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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
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 * accompanied this code).
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package com.sun.crypto.provider;

import java.security.*;
import java.security.spec.AlgorithmParameterSpec;

import javax.crypto.*;
import javax.crypto.spec.SecretKeySpec;

KeyGeneratore core implementation and individual key generator
implementations. Because of US export regulations, we cannot use
subclassing to achieve code sharing between the key generator
implementations for our various algorithms. Instead, we have the
core implementation in this KeyGeneratorCore class, which is used
by the individual implementations. See those further down in this
file.
Author:
 Andreas Sterbenz
Since:
  1.5/**
 * KeyGeneratore core implementation and individual key generator
 * implementations. Because of US export regulations, we cannot use
 * subclassing to achieve code sharing between the key generator
 * implementations for our various algorithms. Instead, we have the
 * core implementation in this KeyGeneratorCore class, which is used
 * by the individual implementations. See those further down in this
 * file.
 *
 * @since   1.5
 * @author  Andreas Sterbenz
 */
final class KeyGeneratorCore {

    // algorithm name to use for the generator keys
    private final String name;

    // default key size in bits
    private final int defaultKeySize;

    // current key size in bits
    private int keySize;

    // PRNG to use
    private SecureRandom random;

    
Construct a new KeyGeneratorCore object with the specified name
and defaultKeySize. Initialize to default key size in case the
application does not call any of the init() methods.
/**
     * Construct a new KeyGeneratorCore object with the specified name
     * and defaultKeySize. Initialize to default key size in case the
     * application does not call any of the init() methods.
     */
    KeyGeneratorCore(String name, int defaultKeySize) {
        this.name = name;
        this.defaultKeySize = defaultKeySize;
        implInit(null);
    }

    // implementation for engineInit(), see JCE doc
    // reset keySize to default
    void implInit(SecureRandom random) {
        this.keySize = defaultKeySize;
        this.random = random;
    }

    // implementation for engineInit(), see JCE doc
    // we do not support any parameters
    void implInit(AlgorithmParameterSpec params, SecureRandom random)
            throws InvalidAlgorithmParameterException {
        throw new InvalidAlgorithmParameterException
            (name + " key generation does not take any parameters");
    }

    // implementation for engineInit(), see JCE doc
    // we enforce a general 40 bit minimum key size for security
    void implInit(int keysize, SecureRandom random) {
        if (keysize < 40) {
            throw new InvalidParameterException
                ("Key length must be at least 40 bits");
        }
        this.keySize = keysize;
        this.random = random;
    }

    // implementation for engineInit(), see JCE doc
    // generate the key
    SecretKey implGenerateKey() {
        if (random == null) {
            random = SunJCE.getRandom();
        }
        byte[] b = new byte[(keySize + 7) >> 3];
        random.nextBytes(b);
        return new SecretKeySpec(b, name);
    }

    // nested static classes for the HmacSHA-2 family of key generator
    abstract static class HmacSHA2KG extends KeyGeneratorSpi {
        private final KeyGeneratorCore core;
        protected HmacSHA2KG(String algoName, int len) {
            core = new KeyGeneratorCore(algoName, len);
        }
        protected void engineInit(SecureRandom random) {
            core.implInit(random);
        }
        protected void engineInit(AlgorithmParameterSpec params,
                SecureRandom random) throws InvalidAlgorithmParameterException {
            core.implInit(params, random);
        }
        protected void engineInit(int keySize, SecureRandom random) {
            core.implInit(keySize, random);
        }
        protected SecretKey engineGenerateKey() {
            return core.implGenerateKey();
        }

        public static final class SHA224 extends HmacSHA2KG {
            public SHA224() {
                super("HmacSHA224", 224);
            }
        }
        public static final class SHA256 extends HmacSHA2KG {
            public SHA256() {
                super("HmacSHA256", 256);
            }
        }
        public static final class SHA384 extends HmacSHA2KG {
            public SHA384() {
                super("HmacSHA384", 384);
            }
        }
        public static final class SHA512 extends HmacSHA2KG {
            public SHA512() {
                super("HmacSHA512", 512);
            }
        }
    }

    // nested static class for the RC2 key generator
    public static final class RC2KeyGenerator extends KeyGeneratorSpi {
        private final KeyGeneratorCore core;
        public RC2KeyGenerator() {
            core = new KeyGeneratorCore("RC2", 128);
        }
        protected void engineInit(SecureRandom random) {
            core.implInit(random);
        }
        protected void engineInit(AlgorithmParameterSpec params,
                SecureRandom random) throws InvalidAlgorithmParameterException {
            core.implInit(params, random);
        }
        protected void engineInit(int keySize, SecureRandom random) {
            if ((keySize < 40) || (keySize > 1024)) {
                throw new InvalidParameterException("Key length for RC2"
                    + " must be between 40 and 1024 bits");
            }
            core.implInit(keySize, random);
        }
        protected SecretKey engineGenerateKey() {
            return core.implGenerateKey();
        }
    }

    // nested static class for the ARCFOUR (RC4) key generator
    public static final class ARCFOURKeyGenerator extends KeyGeneratorSpi {
        private final KeyGeneratorCore core;
        public ARCFOURKeyGenerator() {
            core = new KeyGeneratorCore("ARCFOUR", 128);
        }
        protected void engineInit(SecureRandom random) {
            core.implInit(random);
        }
        protected void engineInit(AlgorithmParameterSpec params,
                SecureRandom random) throws InvalidAlgorithmParameterException {
            core.implInit(params, random);
        }
        protected void engineInit(int keySize, SecureRandom random) {
            if ((keySize < 40) || (keySize > 1024)) {
                throw new InvalidParameterException("Key length for ARCFOUR"
                    + " must be between 40 and 1024 bits");
            }
            core.implInit(keySize, random);
        }
        protected SecretKey engineGenerateKey() {
            return core.implGenerateKey();
        }
    }

}