com.esri.geoportal.harvester.api.base.SimpleScrambler.java Source code

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Here is the source code for com.esri.geoportal.harvester.api.base.SimpleScrambler.java

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/*
 * Copyright 2016 Esri, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.esri.geoportal.harvester.api.base;

import java.io.UnsupportedEncodingException;
import java.util.Base64;
import java.util.zip.CRC32;
import org.apache.commons.lang3.StringUtils;

/**
 * Simple scrambler.
 */
public class SimpleScrambler {

    /**
     * Encodes string.
     * @param txt string to encode
     * @return encoded string or <code>null</code> if error encoding string
     */
    public static String encode(String txt) {
        txt = StringUtils.defaultIfEmpty(txt, "");
        try {
            CRC32 crC32 = new CRC32();
            crC32.update(txt.getBytes("UTF-8"));
            long crc = crC32.getValue();
            String crctxt = String.format("%10d%s", crc, txt);
            Base64.Encoder encoder = Base64.getEncoder();
            return encoder.encodeToString(crctxt.getBytes("UTF-8"));
        } catch (UnsupportedEncodingException ex) {
            return null;
        }
    }

    /**
     * Decodes string.
     * @param encoded encoded string to decode
     * @return decoded string or <code>null</code> if error decoding string
     */
    public static String decode(String encoded) {
        try {
            encoded = StringUtils.defaultIfEmpty(encoded, "");
            Base64.Decoder decoder = Base64.getDecoder();
            String crctxt = new String(decoder.decode(encoded), "UTF-8");
            if (crctxt.length() < 10) {
                return null;
            }
            long crc = Long.parseLong(StringUtils.trimToEmpty(crctxt.substring(0, 10)));
            String txt = crctxt.substring(10);
            CRC32 crC32 = new CRC32();
            crC32.update(txt.getBytes("UTF-8"));
            if (crc != crC32.getValue()) {
                return null;
            }
            return txt;
        } catch (NumberFormatException | UnsupportedEncodingException ex) {
            return null;
        }
    }
}