| 提交 | 用户 | age | ||
| 5c5945 | 1 | /** |
| E | 2 | * 对企业微信发送给企业后台的消息加解密示例代码. |
| 3 | * | |
| 4 | * @copyright Copyright (c) 1998-2014 Tencent Inc. | |
| 5 | */ | |
| 6 | ||
| 7 | // ------------------------------------------------------------------------ | |
| 8 | ||
| 9 | package com.qq.weixin.mp.aes; | |
| 10 | ||
| 11 | import java.nio.charset.Charset; | |
| 12 | import java.util.Arrays; | |
| 13 | ||
| 14 | /** | |
| 15 | * 提供基于PKCS7算法的加解密接口. | |
| 16 | */ | |
| 17 | class PKCS7Encoder { | |
| 18 | static Charset CHARSET = Charset.forName("utf-8"); | |
| 19 | static int BLOCK_SIZE = 32; | |
| 20 | ||
| 21 | /** | |
| 22 | * 获得对明文进行补位填充的字节. | |
| 23 | * | |
| 24 | * @param count 需要进行填充补位操作的明文字节个数 | |
| 25 | * @return 补齐用的字节数组 | |
| 26 | */ | |
| 27 | static byte[] encode(int count) { | |
| 28 | // 计算需要填充的位数 | |
| 29 | int amountToPad = BLOCK_SIZE - (count % BLOCK_SIZE); | |
| 30 | if (amountToPad == 0) { | |
| 31 | amountToPad = BLOCK_SIZE; | |
| 32 | } | |
| 33 | // 获得补位所用的字符 | |
| 34 | char padChr = chr(amountToPad); | |
| 35 | String tmp = new String(); | |
| 36 | for (int index = 0; index < amountToPad; index++) { | |
| 37 | tmp += padChr; | |
| 38 | } | |
| 39 | return tmp.getBytes(CHARSET); | |
| 40 | } | |
| 41 | ||
| 42 | /** | |
| 43 | * 删除解密后明文的补位字符 | |
| 44 | * | |
| 45 | * @param decrypted 解密后的明文 | |
| 46 | * @return 删除补位字符后的明文 | |
| 47 | */ | |
| 48 | static byte[] decode(byte[] decrypted) { | |
| 49 | int pad = (int) decrypted[decrypted.length - 1]; | |
| 50 | if (pad < 1 || pad > 32) { | |
| 51 | pad = 0; | |
| 52 | } | |
| 53 | return Arrays.copyOfRange(decrypted, 0, decrypted.length - pad); | |
| 54 | } | |
| 55 | ||
| 56 | /** | |
| 57 | * 将数字转化成ASCII码对应的字符，用于对明文进行补码 | |
| 58 | * | |
| 59 | * @param a 需要转化的数字 | |
| 60 | * @return 转化得到的字符 | |
| 61 | */ | |
| 62 | static char chr(int a) { | |
| 63 | byte target = (byte) (a & 0xFF); | |
| 64 | return (char) target; | |
| 65 | } | |
| 66 | ||
| 67 | } | |
