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/*********************************************************************************
 *                                                                               *
 * The MIT License (MIT)                                                         *
 *                                                                               *
 * Copyright (c) 2015-2020 aoju.org and other contributors.                      *
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 * Permission is hereby granted, free of charge, to any person obtaining a copy  *
 * of this software and associated documentation files (the "Software"), to deal *
 * in the Software without restriction, including without limitation the rights  *
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell     *
 * copies of the Software, and to permit persons to whom the Software is         *
 * furnished to do so, subject to the following conditions:                      *
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 * The above copyright notice and this permission notice shall be included in    *
 * all copies or substantial portions of the Software.                           *
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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR    *
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,      *
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE   *
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 * THE SOFTWARE.                                                                 *
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package org.aoju.bus.crypto.symmetric;

/**
 * 维吉尼亚密码实现
 * 人们在恺撒移位密码的基础上扩展出多表密码,称为维吉尼亚密码
 * 算法实现来自:https://github.com/zhaorenjie110/SymmetricEncryptionAndDecryption
 *
 * @author Kimi Liu
 * @version 6.1.1
 * @since JDK 1.8+
 */
public class Vigenere {

    /**
     * 加密
     *
     * @param data      数据
     * @param cipherKey 密钥
     * @return 密文
     */
    public static String encrypt(CharSequence data, CharSequence cipherKey) {
        final int dataLen = data.length();
        final int cipherKeyLen = cipherKey.length();

        final char[] cipherArray = new char[dataLen];
        for (int i = 0; i < dataLen / cipherKeyLen + 1; i++) {
            for (int t = 0; t < cipherKeyLen; t++) {
                if (t + i * cipherKeyLen < dataLen) {
                    final char dataChar = data.charAt(t + i * cipherKeyLen);
                    final char cipherKeyChar = cipherKey.charAt(t);
                    cipherArray[t + i * cipherKeyLen] = (char) ((dataChar + cipherKeyChar - 64) % 95 + 32);
                }
            }
        }

        return String.valueOf(cipherArray);
    }

    /**
     * 解密
     *
     * @param data      密文
     * @param cipherKey 密钥
     * @return 明文
     */
    public static String decrypt(CharSequence data, CharSequence cipherKey) {
        final int dataLen = data.length();
        final int cipherKeyLen = cipherKey.length();

        final char[] clearArray = new char[dataLen];
        for (int i = 0; i < dataLen; i++) {
            for (int t = 0; t < cipherKeyLen; t++) {
                if (t + i * cipherKeyLen < dataLen) {
                    final char dataChar = data.charAt(t + i * cipherKeyLen);
                    final char cipherKeyChar = cipherKey.charAt(t);
                    if (dataChar - cipherKeyChar >= 0) {
                        clearArray[t + i * cipherKeyLen] = (char) ((dataChar - cipherKeyChar) % 95 + 32);
                    } else {
                        clearArray[t + i * cipherKeyLen] = (char) ((dataChar - cipherKeyChar + 95) % 95 + 32);
                    }
                }
            }
        }
        return String.valueOf(clearArray);
    }

}




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