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前言

最近工作中需要实现HBase自定义扩展sms4加密，今天就先来说一下Java版的SMS4加密解密算法的具体实现。

一、概述

1.1 基本概念

本算法是一个分组算法，由加解密算法和密钥扩展算法组成。该算法的分组长度为128比特(Bit)，密钥长度为128比特(Bit)，也就是16个字节(Bytes)。加密算法与密钥扩展算法都采用32轮非线性迭代结构。解密算法与加密算法的结构相同，只是轮密钥的使用顺序相反，解密轮密钥是加密轮密钥的逆序。在SMS4的基础类中，你会看到加密和解密的基础函数是同一个(本篇文章中的sms4KeyExt()方法)，只是需要一个int型的标志位来判断是加密还是解密。

1.2 密码算法结构

基本轮函数加迭代
解密算法与加密算法相同

1.3 S盒：S-box

S 盒为固定的8比特(Bit)输入8比特(Bit)输出的置换，记为Sbox(⋅) 。

1.4 SMS4密码算法

1.4.1 基本运算

⨁ 32比特异或
⋘ i 32比特循环左移i位

1.4.2 基本密码部件

非线性字节变换部件S盒
非线性字变换τ：32位字的非线性变换
字线性部件L变换
字合成变换T

1.4.3 轮函数F

1.5 密钥扩展算法

常数FK
固定参数CK

更多详细的资料请私信 “sms4” 到本头条号，获取SMS4相关资料(一个PPT，一个PDF)。

二、编码实现

以下代码可能与网上有些雷同，毕竟万变不离其宗，但我将每一个方法代表什么意思，都写了很详细的注释供大家理解，这样可以缩短你的学习时长。都快被自己感动哭了

package com.xxx.sms4;import java.util.Arrays;/** * @author CREATE_17 * @description: SMS4加密与解密算法实现 * @date: 2019/4/2 14:10 */public class Sms4 { /** * @description: ENCRYPT与DECRYPT为加解密的判断依据 */ private static final int ENCRYPT = 1; private static final int DECRYPT = 0; /** * @description: 轮数，轮函数的迭代次数 * 加密算法与密钥扩展算法都采用32轮非线性迭代结构。 */ private static final int ROUND = 32; private static final int BLOCK = 16; /** * @description: S盒中数据均采用16进制表示 */ private static short[] sBox = { 0xd6, 0x90, 0xe9, 0xfe, 0xcc, 0xe1, 0x3d, 0xb7, 0x16, 0xb6, 0x14, 0xc2, 0x28, 0xfb, 0x2c, 0x05, 0x2b, 0x67, 0x9a, 0x76, 0x2a, 0xbe, 0x04, 0xc3, 0xaa, 0x44, 0x13, 0x26, 0x49, 0x86, 0x06, 0x99, 0x9c, 0x42, 0x50, 0xf4, 0x91, 0xef, 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43, 0xed, 0xcf, 0xac, 0x62, 0xe4, 0xb3, 0x1c, 0xa9, 0xc9, 0x08, 0xe8, 0x95, 0x80, 0xdf, 0x94, 0xfa, 0x75, 0x8f, 0x3f, 0xa6, 0x47, 0x07, 0xa7, 0xfc, 0xf3, 0x73, 0x17, 0xba, 0x83, 0x59, 0x3c, 0x19, 0xe6, 0x85, 0x4f, 0xa8, 0x68, 0x6b, 0x81, 0xb2, 0x71, 0x64, 0xda, 0x8b, 0xf8, 0xeb, 0x0f, 0x4b, 0x70, 0x56, 0x9d, 0x35, 0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, 0xd1, 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, 0x87, 0xd4, 0x00, 0x46, 0x57, 0x9f, 0xd3, 0x27, 0x52, 0x4c, 0x36, 0x02, 0xe7, 0xa0, 0xc4, 0xc8, 0x9e, 0xea, 0xbf, 0x8a, 0xd2, 0x40, 0xc7, 0x38, 0xb5, 0xa3, 0xf7, 0xf2, 0xce, 0xf9, 0x61, 0x15, 0xa1, 0xe0, 0xae, 0x5d, 0xa4, 0x9b, 0x34, 0x1a, 0x55, 0xad, 0x93, 0x32, 0x30, 0xf5, 0x8c, 0xb1, 0xe3, 0x1d, 0xf6, 0xe2, 0x2e, 0x82, 0x66, 0xca, 0x60, 0xc0, 0x29, 0x23, 0xab, 0x0d, 0x53, 0x4e, 0x6f, 0xd5, 0xdb, 0x37, 0x45, 0xde, 0xfd, 0x8e, 0x2f, 0x03, 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b, 0x51, 0x8d, 0x1b, 0xaf, 0x92, 0xbb, 0xdd, 0xbc, 0x7f, 0x11, 0xd9, 0x5c, 0x41, 0x1f, 0x10, 0x5a, 0xd8, 0x0a, 0xc1, 0x31, 0x88, 0xa5, 0xcd, 0x7b, 0xbd, 0x2d, 0x74, 0xd0, 0x12, 0xb8, 0xe5, 0xb4, 0xb0, 0x89, 0x69, 0x97, 0x4a, 0x0c, 0x96, 0x77, 0x7e, 0x65, 0xb9, 0xf1, 0x09, 0xc5, 0x6e, 0xc6, 0x84, 0x18, 0xf0, 0x7d, 0xec, 0x3a, 0xdc, 0x4d, 0x20, 0x79, 0xee, 0x5f, 0x3e, 0xd7, 0xcb, 0x39, 0x48 }; /** * @description: 常数FK，在密钥扩展中使用一些常数 */ private static int[] fk = {0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc}; /** * @description: 32个固定参数CK * 产生规则：Ckij= (4i+j)×7(mod 256) ，i=0,1,2…31,j=0,1,…3 */ private static int[] ck = { 0x00070e15, 0x1c232a31, 0x383f464d, 0x545b6269, 0x70777e85, 0x8c939aa1, 0xa8afb6bd, 0xc4cbd2d9, 0xe0e7eef5, 0xfc030a11, 0x181f262d, 0x343b4249, 0x50575e65, 0x6c737a81, 0x888f969d, 0xa4abb2b9, 0xc0c7ced5, 0xdce3eaf1, 0xf8ff060d, 0x141b2229, 0x30373e45, 0x4c535a61, 0x686f767d, 0x848b9299, 0xa0a7aeb5, 0xbcc3cad1, 0xd8dfe6ed, 0xf4fb0209, 0x10171e25, 0x2c333a41, 0x484f565d, 0x646b7279 }; /** * @description: 移位，rot1(x,y)为循环左移位y * @param: x * @param: y * @return: int */ private int rotl(int x, int y) { return x << y | x >>> (32 - y); } /** * @description: 加解密，非线性τ函数：B=τ(A) * @param: a * @return: int */ private int byteSub(int a) { return (sBox[a >>> 24 & 0xFF] & 0xFF) << 24 ^ (sBox[a >>> 16 & 0xFF] & 0xFF) << 16 ^ (sBox[a >>> 8 & 0xFF] & 0xFF) << 8 ^ (sBox[a & 0xFF] & 0xFF); } /** * @description: 加解密的L函数 * @param: b * @return: int */ private int l1(int b) { return b ^ rotl(b, 2) ^ rotl(b, 10) ^ rotl(b, 18) ^ rotl(b, 24); } /** * @description: 密钥扩展 * @param: b * @return: int */ private int l2(int b) { return b ^ rotl(b, 13) ^ rotl(b, 23); } /** * @description: SMS4的加密方法实现 * @param: input(待输入的明文) * @param: output(待输出的密文) * @param: rk(轮密钥) * @return: void */ private void sms4Crypt(byte[] input, byte[] output, int[] rk) { int mid; int[] x = new int[4]; int[] tmp = new int[4]; for (int i = 0; i < 4; i++) { tmp[0] = input[4 * i] & 0xff; tmp[1] = input[1 + 4 * i] & 0xff; tmp[2] = input[2 + 4 * i] & 0xff; tmp[3] = input[3 + 4 * i] & 0xff; x[i] = tmp[0] << 24 | tmp[1] << 16 | tmp[2] << 8 | tmp[3]; } // 进行32轮的加密变换操作 for (int r = 0; r < 32; r += 4) { mid = x[1] ^ x[2] ^ x[3] ^ rk[r]; mid = byteSub(mid); // x4 x[0] = x[0] ^ l1(mid); mid = x[2] ^ x[3] ^ x[0] ^ rk[r + 1]; mid = byteSub(mid); // x5 x[1] = x[1] ^ l1(mid); mid = x[3] ^ x[0] ^ x[1] ^ rk[r + 2]; mid = byteSub(mid); // x6 x[2] = x[2] ^ l1(mid); mid = x[0] ^ x[1] ^ x[2] ^ rk[r + 3]; mid = byteSub(mid); // x7 x[3] = x[3] ^ l1(mid); } // 反序变换 for (int j = 0; j < 16; j += 4) { output[j] = (byte) (x[3 - j / 4] >>> 24 & 0xFF); output[j + 1] = (byte) (x[3 - j / 4] >>> 16 & 0xFF); output[j + 2] = (byte) (x[3 - j / 4] >>> 8 & 0xFF); output[j + 3] = (byte) (x[3 - j / 4] & 0xFF); } } /** * @description: SMS4的密钥扩展算法 * @param: key(加密密钥) * @param: rk(子密钥) * @param: cryptFlag(加解密标志) * @return: void */ private void sms4KeyExt(byte[] key, int[] rk, int cryptFlag) { int r, mid; int[] x = new int[4]; int[] tmp = new int[4]; for (int i = 0; i < 4; i++) { // 实现对初始密钥的分组(分为4组) tmp[0] = key[4 * i] & 0xFF; tmp[1] = key[1 + 4 * i] & 0xff; tmp[2] = key[2 + 4 * i] & 0xff; tmp[3] = key[3 + 4 * i] & 0xff; x[i] = tmp[0] << 24 | tmp[1] << 16 | tmp[2] << 8 | tmp[3]; x[i] = key[4 * i] << 24 | key[1 + 4 * i] << 16 | key[2 + 4 * i] << 8 | key[3 + 4 * i]; } // 异或运算之后的结果 x[0] ^= fk[0]; x[1] ^= fk[1]; x[2] ^= fk[2]; x[3] ^= fk[3]; for (r = 0; r < 32; r += 4) { // mid = x[1] ^ x[2] ^ x[3] ^ ck[r]; mid = byteSub(mid); // rk0=K4 rk[r] = x[0] ^= l2(mid); mid = x[2] ^ x[3] ^ x[0] ^ ck[r + 1]; mid = byteSub(mid); // rk1=K5 rk[r + 1] = x[1] ^= l2(mid); mid = x[3] ^ x[0] ^ x[1] ^ ck[r + 2]; mid = byteSub(mid); // rk2=K6 rk[r + 2] = x[2] ^= l2(mid); mid = x[0] ^ x[1] ^ x[2] ^ ck[r + 3]; mid = byteSub(mid); // rk3=K7 rk[r + 3] = x[3] ^= l2(mid); } // cryptFla==0 为解密，解密时轮密钥使用顺序：rk31,rk30,...,rk0(逆序) if (cryptFlag == DECRYPT) { for (r = 0; r < 16; r++) { mid = rk[r]; rk[r] = rk[31 - r]; rk[31 - r] = mid; } } } /** * @description: 加解密的基础方法 * @param: in(待输入的明文或密文) * @param: inLen(16) * @param: key(密钥) * @param: out(待输出的密文或明文) * @param: cryptFlag(加解密的判断条件) * @return: int */ private void sms4(byte[] in, int inLen, byte[] key, byte[] out, int cryptFlag) { int point = 0; int[] roundKey = new int[ROUND]; sms4KeyExt(key, roundKey, cryptFlag); byte[] input; byte[] output = new byte[16]; while (inLen >= BLOCK) { input = Arrays.copyOfRange(in, point, point + 16); sms4Crypt(input, output, roundKey); System.arraycopy(output, 0, out, point, BLOCK); inLen -= BLOCK; point += BLOCK; } } /** * @description: 明文加密 * @param: plaintext(明文) * @param: key(密钥) * @return: byte[] */ private static byte[] encodeSMS4(String plaintext, byte[] key) { if (plaintext == null || "".equals(plaintext)) { return null; } for (int i = plaintext.getBytes().length % 16; i < 16; i++) { plaintext += '0'; } return Sms4.encodeSMS4(plaintext.getBytes(), key); } /** * @description: 不限明文长度的SMS4加密 * @param: plainText(明文) * @param: key(密钥) * @return: byte类型的明文加密结果 */ private static byte[] encodeSMS4(byte[] plainText, byte[] key) { byte[] ciphertext = new byte[plainText.length]; int k = 0; int plainLen = plainText.length; while (k + 16 <= plainLen) { byte[] cellPlain = new byte[16]; for (int i = 0; i < 16; i++) { cellPlain[i] = plainText[k + i]; } byte[] cellCipher = encode16(cellPlain, key); for (int i = 0; i < cellCipher.length; i++) { ciphertext[k + i] = cellCipher[i]; } k += 16; } return ciphertext; } /** * @description: 不限密文长度的SMS4解密，获得byte类型的明文 * @param: cipherText(密文) * @param: key(密钥) * @return: byte[] */ private static byte[] decodeSMS4(byte[] cipherText, byte[] key) { byte[] plaintext = new byte[cipherText.length]; int k = 0; int cipherLen = cipherText.length; while (k + 16 <= cipherLen) { byte[] cellCipher = new byte[16]; for (int i = 0; i < 16; i++) { cellCipher[i] = cipherText[k + i]; } byte[] cellPlain = decode16(cellCipher, key); for (int i = 0; i < cellPlain.length; i++) { plaintext[k + i] = cellPlain[i]; } k += 16; } return plaintext; } /** * @description: 解密，获得明文字符串 * @param: cipherText(密文) * @param: key(密钥) * @return: java.lang.String */ private static String decodeSMS4toString(byte[] cipherText, byte[] key) { byte[] plaintext = new byte[cipherText.length]; plaintext = decodeSMS4(cipherText, key); return new String(plaintext); } /** * @description: 16位明文加密，得到密文 * @param: plainText(明文) * @param: key(密钥) * @return: byte[] */ private static byte[] encode16(byte[] plainText, byte[] key) { byte[] cipher = new byte[16]; Sms4 sm4 = new Sms4(); sm4.sms4(plainText, 16, key, cipher, ENCRYPT); return cipher; } /** * @description: 解密密文，返回字节类型的明文 * @param: key * @return: byte[] */ private static byte[] decode16(byte[] ciphertext, byte[] key) { byte[] plain = new byte[16]; Sms4 sm4 = new Sms4(); sm4.sms4(ciphertext, 16, key, plain, DECRYPT); return plain; } /** * @description: 将16进制byte类型的密文转换为String字符串 * @param: byteArray * @return: java.lang.String */ private static String toHexString(byte[] byteArray) { if (byteArray == null || byteArray.length < 1) { throw new IllegalArgumentException("this byteArray must not be null or empty"); } final StringBuilder hexString = new StringBuilder(); for (int i = 0; i < byteArray.length; i++) { if ((byteArray[i] & 0xff) < 0x10) { hexString.append("0"); } hexString.append(Integer.toHexString(0xFF & byteArray[i])); } return hexString.toString().toLowerCase(); } public static void main(String[] args) { // 密钥 byte[] key = {0x01, 0x23, 0x45, 0x67, (byte) 0x89, (byte) 0xab, (byte) 0xcd, (byte) 0xef, (byte) 0xfe, (byte) 0xdc, (byte) 0xba, (byte) 0x98, 0x76, 0x54, 0x32, 0x10};// byte[] key = "JeF8U9wHFOMfs2S3".getBytes(); // 明文 String plainText = "SMS4测试，大数据实战演练！"; byte[] enOut = encodeSMS4(plainText, key); if (enOut == null) { return; } System.out.println("加密结果："); System.out.println(toHexString(enOut)); byte[] deOut = decodeSMS4(enOut, key); System.out.println("解密结果(return byte[])："); System.out.println(Arrays.toString(deOut)); String deOutStr = decodeSMS4toString(enOut, key); System.out.println("解密结果(return String)：" + deOutStr); }}

明文设置为“SMS4测试，大数据实战演练！”，程序会对明文进行加密，然后在对密文进行解密。直接运行程序，得到加密与解密结果，如下图所示：