com.qq.weixin.mp.aes.PKCS7Encoder Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of weixin-popular Show documentation
Show all versions of weixin-popular Show documentation
The weixin-popular is a JAVA SDK for weixin. Weixin web url is https://mp.weixin.qq.com.
/**
* 对公众平台发送给公众账号的消息加解密示例代码.
*
* @copyright Copyright (c) 1998-2014 Tencent Inc.
*/
// ------------------------------------------------------------------------
package com.qq.weixin.mp.aes;
import java.nio.charset.Charset;
import java.util.Arrays;
/**
* 提供基于PKCS7算法的加解密接口.
*/
public class PKCS7Encoder {
static Charset CHARSET = Charset.forName("utf-8");
static 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(CHARSET);
}
/**
* 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
*/
static char chr(int a) {
byte target = (byte) (a & 0xFF);
return (char) target;
}
}