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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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,
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 *
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package com.sun.crypto.provider;

import java.util.Arrays;
import java.nio.ByteBuffer;

import javax.crypto.MacSpi;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.spec.PBEParameterSpec;
import java.security.*;
import java.security.spec.*;

/**
 * This is an implementation of the PBMAC1 algorithms as defined
 * in PKCS#5 v2.1 standard.
 */
abstract class PBMAC1Core extends HmacCore {

    // NOTE: this class inherits the Cloneable interface from HmacCore
    // Need to override clone() if mutable fields are added.
    private final String kdfAlgo;
    private final String hashAlgo;
    private final int blockLength; // in octets

    /**
     * Creates an instance of PBMAC1 according to the selected
     * password-based key derivation function.
     */
    PBMAC1Core(String kdfAlgo, String hashAlgo, int blockLength)
        throws NoSuchAlgorithmException {
        super(hashAlgo, blockLength);
        this.kdfAlgo = kdfAlgo;
        this.hashAlgo = hashAlgo;
        this.blockLength = blockLength;
    }

    private static PBKDF2Core getKDFImpl(String algo) {
        PBKDF2Core kdf = null;
        switch(algo) {
        case "HmacSHA1":
                kdf = new PBKDF2Core.HmacSHA1();
                break;
        case "HmacSHA224":
                kdf = new PBKDF2Core.HmacSHA224();
                break;
        case "HmacSHA256":
                kdf = new PBKDF2Core.HmacSHA256();
                break;
        case "HmacSHA384":
                kdf = new PBKDF2Core.HmacSHA384();
                break;
        case "HmacSHA512":
                kdf = new PBKDF2Core.HmacSHA512();
                break;
        default:
                throw new ProviderException(
                    "No MAC implementation for " + algo);
        }
        return kdf;
    }

    /**
     * Initializes the HMAC with the given secret key and algorithm parameters.
     *
     * @param key the secret key.
     * @param params the algorithm parameters.
     *
     * @exception InvalidKeyException if the given key is inappropriate for
     * initializing this MAC.
     * @exception InvalidAlgorithmParameterException if the given algorithm
     * parameters are inappropriate for this MAC.
     */
    protected void engineInit(Key key, AlgorithmParameterSpec params)
        throws InvalidKeyException, InvalidAlgorithmParameterException {
        char[] passwdChars;
        byte[] salt = null;
        int iCount = 0;
        if (key instanceof javax.crypto.interfaces.PBEKey) {
            javax.crypto.interfaces.PBEKey pbeKey =
                (javax.crypto.interfaces.PBEKey) key;
            passwdChars = pbeKey.getPassword();
            salt = pbeKey.getSalt(); // maybe null if unspecified
            iCount = pbeKey.getIterationCount(); // maybe 0 if unspecified
        } else if (key instanceof SecretKey) {
            byte[] passwdBytes;
            if (!(key.getAlgorithm().regionMatches(true, 0, "PBE", 0, 3)) ||
                    (passwdBytes = key.getEncoded()) == null) {
                throw new InvalidKeyException("Missing password");
            }
            passwdChars = new char[passwdBytes.length];
            for (int i=0; i<passwdChars.length; i++) {
                passwdChars[i] = (char) (passwdBytes[i] & 0x7f);
            }
            Arrays.fill(passwdBytes, (byte)0x00);
        } else {
            throw new InvalidKeyException("SecretKey of PBE type required");
        }

        PBEKeySpec pbeSpec;
        try {
            if (params == null) {
                // should not auto-generate default values since current
                // javax.crypto.Mac api does not have any method for caller to
                // retrieve the generated defaults.
                if ((salt == null) || (iCount == 0)) {
                    throw new InvalidAlgorithmParameterException
                            ("PBEParameterSpec required for salt and iteration count");
                }
            } else if (!(params instanceof PBEParameterSpec)) {
                throw new InvalidAlgorithmParameterException
                        ("PBEParameterSpec type required");
            } else {
                PBEParameterSpec pbeParams = (PBEParameterSpec) params;
                // make sure the parameter values are consistent
                if (salt != null) {
                    if (!Arrays.equals(salt, pbeParams.getSalt())) {
                        throw new InvalidAlgorithmParameterException
                                ("Inconsistent value of salt between key and params");
                    }
                } else {
                    salt = pbeParams.getSalt();
                }
                if (iCount != 0) {
                    if (iCount != pbeParams.getIterationCount()) {
                        throw new InvalidAlgorithmParameterException
                                ("Different iteration count between key and params");
                    }
                } else {
                    iCount = pbeParams.getIterationCount();
                }
            }
            // For security purpose, we need to enforce a minimum length
            // for salt; just require the minimum salt length to be 8-byte
            // which is what PKCS#5 recommends and openssl does.
            if (salt.length < 8) {
                throw new InvalidAlgorithmParameterException
                        ("Salt must be at least 8 bytes long");
            }
            if (iCount <= 0) {
                throw new InvalidAlgorithmParameterException
                        ("IterationCount must be a positive number");
            }

            pbeSpec = new PBEKeySpec(passwdChars, salt, iCount, blockLength);
            // password char[] was cloned in PBEKeySpec constructor,
            // so we can zero it out here
        } finally {
            Arrays.fill(passwdChars, '\0');
        }

        SecretKey s;
        PBKDF2Core kdf = getKDFImpl(kdfAlgo);
        try {
            s = kdf.engineGenerateSecret(pbeSpec);
        } catch (InvalidKeySpecException ikse) {
            InvalidKeyException ike =
                new InvalidKeyException("Cannot construct PBE key");
            ike.initCause(ikse);
            throw ike;
        }
        byte[] derivedKey = s.getEncoded();
        SecretKey cipherKey = new SecretKeySpec(derivedKey, kdfAlgo);

        super.engineInit(cipherKey, null);
    }

    public static final class HmacSHA1 extends PBMAC1Core {
        public HmacSHA1() throws NoSuchAlgorithmException {
            super("HmacSHA1", "SHA1", 64);
        }
    }

    public static final class HmacSHA224 extends PBMAC1Core {
        public HmacSHA224() throws NoSuchAlgorithmException {
            super("HmacSHA224", "SHA-224", 64);
        }
    }

    public static final class HmacSHA256 extends PBMAC1Core {
        public HmacSHA256() throws NoSuchAlgorithmException {
            super("HmacSHA256", "SHA-256", 64);
        }
    }

    public static final class HmacSHA384 extends PBMAC1Core {
        public HmacSHA384() throws NoSuchAlgorithmException {
            super("HmacSHA384", "SHA-384", 128);
        }
    }

    public static final class HmacSHA512 extends PBMAC1Core {
        public HmacSHA512() throws NoSuchAlgorithmException {
            super("HmacSHA512", "SHA-512", 128);
        }
    }
}
