/*

 * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.

 * 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.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 */

package sun.security.provider;

import sun.security.util.HexDumpEncoder;

import java.util.ArrayList;

import java.util.List;

import java.util.Locale;

public abstract class AbstractHashDrbg extends AbstractDrbg {

    protected int outLen;

    protected int seedLen;

    private static int alg2strength(String algorithm) {

        switch (algorithm.toUpperCase(Locale.ROOT)) {

            case "SHA-224":

            case "SHA-512/224":

                return 192;

            case "SHA-256":

            case "SHA-512/256":

            case "SHA-384":

            case "SHA-512":

                return 256;

            default:

                throw new IllegalArgumentException(algorithm +

                        " not supported in Hash_DBRG");

        }

    }

    protected void chooseAlgorithmAndStrength() {

        if (requestedAlgorithm != null) {

            algorithm = requestedAlgorithm.toUpperCase(Locale.ROOT);

            int supportedStrength = alg2strength(algorithm);

            if (requestedInstantiationSecurityStrength >= 0) {

                int tryStrength = getStandardStrength(

                        requestedInstantiationSecurityStrength);

                if (tryStrength > supportedStrength) {

                    throw new IllegalArgumentException(algorithm +

                            " does not support strength " +

                            requestedInstantiationSecurityStrength);

                }

                this.securityStrength = tryStrength;

            } else {

                this.securityStrength = DEFAULT_STRENGTH > supportedStrength ?

                        supportedStrength : DEFAULT_STRENGTH;

            }

        } else {

            int tryStrength = (requestedInstantiationSecurityStrength < 0) ?

                    DEFAULT_STRENGTH : requestedInstantiationSecurityStrength;

            tryStrength = getStandardStrength(tryStrength);

            // The default algorithm which is enough for all strengths.

            // Remember to sync with "securerandom.drbg.config" in java.security

            algorithm = "SHA-256";

            this.securityStrength = tryStrength;

        }

        switch (algorithm.toUpperCase(Locale.ROOT)) {

            case "SHA-224":

            case "SHA-512/224":

                this.seedLen = 440 / 8;

                this.outLen = 224 / 8;

                break;

            case "SHA-256":

            case "SHA-512/256":

                this.seedLen = 440 / 8;

                this.outLen = 256 / 8;

                break;

            case "SHA-384":

                this.seedLen = 888 / 8;

                this.outLen = 384 / 8;

                break;

            case "SHA-512":

                this.seedLen = 888 / 8;

                this.outLen = 512 / 8;

                break;

            default:

                throw new IllegalArgumentException(algorithm +

                        " not supported in Hash_DBRG");

        }

        this.minLength = this.securityStrength / 8;

    }

    @Override

    public void instantiateAlgorithm(byte[] entropy) {

        if (debug != null) {

            debug.println(this, "instantiate");

        }

        // 800-90Ar1 10.1.1.2: Hash_DRBG Instantiate Process.

        // 800-90Ar1 10.1.2.3: Hmac_DRBG Instantiate Process.

        // Step 1: entropy_input || nonce || personalization_string.

        List<byte[]> inputs = new ArrayList<>(3);

        inputs.add(entropy);

        inputs.add(nonce);

        if (personalizationString != null) {

            inputs.add(personalizationString);

        }

        hashReseedInternal(inputs);

    }

    @Override

    protected void reseedAlgorithm(

            byte[] ei,

            byte[] additionalInput) {

        if (debug != null) {

            debug.println(this, "reseedAlgorithm\n" +

                    new HexDumpEncoder().encodeBuffer(ei) + "\n" +

                    ((additionalInput == null) ? "" :

                        new HexDumpEncoder().encodeBuffer(additionalInput)));

        }

        // 800-90Ar1 10.1.1.3: Hash_DRBG Reseed Process.

        // 800-90Ar1 10.1.2.4: Hmac_DRBG Reseed Process.

        // Step 1: entropy_input || additional_input.

        List<byte[]> inputs = new ArrayList<>(2);

        inputs.add(ei);

        if (additionalInput != null) {

            inputs.add(additionalInput);

        }

        hashReseedInternal(inputs);

    }

    /**

     * Operates on multiple inputs.

     * @param inputs not null, each element neither null

     */

    protected abstract void hashReseedInternal(List<byte[]> inputs);

}