com.baomidou.kisso.common.encrypt.PKCS7Encoder Maven / Gradle / Ivy
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/*
* Copyright (c) 2011-2020, hubin ([email protected]).
*
* 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.baomidou.kisso.common.encrypt;
import java.util.Arrays;
import com.baomidou.kisso.common.SSOConstants;
/**
*
* 提供基于 PKCS7 算法的加解密
*
*
* @author hubin
* @since 2015-01-09
*/
public class PKCS7Encoder {
private static final int BLOCK_SIZE = 32;
/**
*
* 获得对明文进行补位填充的字节
*
*
* @param count 需要进行填充补位操作的明文字节个数
* @return 补齐用的字节数组
*/
public static byte[] encode(int count) {
/* 计算需要填充的位数 */
int amountToPad = BLOCK_SIZE - (count % BLOCK_SIZE);
if (amountToPad == 0) {
amountToPad = BLOCK_SIZE;
}
/* 获得补位所用的字符 */
char padChr = chr(amountToPad);
String tmp = new String();
for (int index = 0; index < amountToPad; index++) {
tmp += padChr;
}
return tmp.getBytes(SSOConstants.CHARSET_ENCODING);
}
/**
*
* 删除解密后明文的补位字符
*
*
* @param decrypted 解密后的明文
* @return 删除补位字符后的明文
*/
public static byte[] decode(byte[] decrypted) {
int pad = (int) decrypted[decrypted.length - 1];
if (pad < 1 || pad > 32) {
pad = 0;
}
return Arrays.copyOfRange(decrypted, 0, decrypted.length - pad);
}
/**
*
* 将数字转化成ASCII码对应的字符，用于对明文进行补码
*
*
* @param a 需要转化的数字
* @return 转化得到的字符
*/
public static char chr(int a) {
byte target = (byte) (a & 0xFF);
return (char) target;
}
}