SMS4简介：
本算法是一个分组算法。该算法的分组长度为128比特，密钥长度为128比特，也就是16个字节。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。所有在SMS4的基础类中，你会看到加密和解密的基础函数是同一个，只是需要一个int型的标志位来判断是加密还是解密。
SMS4加密算法基础类：
public class SMS4 {
private static final int ENCRYPT = 1;
private static final int DECRYPT = 0;
public static final int ROUND = 32;
private static final int BLOCK = 16;
private byte[] Sbox = { (byte) 0xd6, (byte) 0x90, (byte) 0xe9, (byte) 0xfe,
(byte) 0xcc, (byte) 0xe1, 0x3d, (byte) 0xb7, 0x16, (byte) 0xb6,
0x14, (byte) 0xc2, 0x28, (byte) 0xfb, 0x2c, 0x05, 0x2b, 0x67,
(byte) 0x9a, 0x76, 0x2a, (byte) 0xbe, 0x04, (byte) 0xc3,
(byte) 0xaa, 0x44, 0x13, 0x26, 0x49, (byte) 0x86, 0x06,
(byte) 0x99, (byte) 0x9c, 0x42, 0x50, (byte) 0xf4, (byte) 0x91,
(byte) 0xef, (byte) 0x98, 0x7a, 0x33, 0x54, 0x0b, 0x43,
(byte) 0xed, (byte) 0xcf, (byte) 0xac, 0x62, (byte) 0xe4,
(byte) 0xb3, 0x1c, (byte) 0xa9, (byte) 0xc9, 0x08, (byte) 0xe8,
(byte) 0x95, (byte) 0x80, (byte) 0xdf, (byte) 0x94, (byte) 0xfa,
0x75, (byte) 0x8f, 0x3f, (byte) 0xa6, 0x47, 0x07, (byte) 0xa7,
(byte) 0xfc, (byte) 0xf3, 0x73, 0x17, (byte) 0xba, (byte) 0x83,
0x59, 0x3c, 0x19, (byte) 0xe6, (byte) 0x85, 0x4f, (byte) 0xa8,
0x68, 0x6b, (byte) 0x81, (byte) 0xb2, 0x71, 0x64, (byte) 0xda,
(byte) 0x8b, (byte) 0xf8, (byte) 0xeb, 0x0f, 0x4b, 0x70, 0x56,
(byte) 0x9d, 0x35, 0x1e, 0x24, 0x0e, 0x5e, 0x63, 0x58, (byte) 0xd1,
(byte) 0xa2, 0x25, 0x22, 0x7c, 0x3b, 0x01, 0x21, 0x78, (byte) 0x87,
(byte) 0xd4, 0x00, 0x46, 0x57, (byte) 0x9f, (byte) 0xd3, 0x27,
0x52, 0x4c, 0x36, 0x02, (byte) 0xe7, (byte) 0xa0, (byte) 0xc4,
(byte) 0xc8, (byte) 0x9e, (byte) 0xea, (byte) 0xbf, (byte) 0x8a,
(byte) 0xd2, 0x40, (byte) 0xc7, 0x38, (byte) 0xb5, (byte) 0xa3,
(byte) 0xf7, (byte) 0xf2, (byte) 0xce, (byte) 0xf9, 0x61, 0x15,
(byte) 0xa1, (byte) 0xe0, (byte) 0xae, 0x5d, (byte) 0xa4,
(byte) 0x9b, 0x34, 0x1a, 0x55, (byte) 0xad, (byte) 0x93, 0x32,
0x30, (byte) 0xf5, (byte) 0x8c, (byte) 0xb1, (byte) 0xe3, 0x1d,
(byte) 0xf6, (byte) 0xe2, 0x2e, (byte) 0x82, 0x66, (byte) 0xca,
0x60, (byte) 0xc0, 0x29, 0x23, (byte) 0xab, 0x0d, 0x53, 0x4e, 0x6f,
(byte) 0xd5, (byte) 0xdb, 0x37, 0x45, (byte) 0xde, (byte) 0xfd,
(byte) 0x8e, 0x2f, 0x03, (byte) 0xff, 0x6a, 0x72, 0x6d, 0x6c, 0x5b,
0x51, (byte) 0x8d, 0x1b, (byte) 0xaf, (byte) 0x92, (byte) 0xbb,
(byte) 0xdd, (byte) 0xbc, 0x7f, 0x11, (byte) 0xd9, 0x5c, 0x41,
0x1f, 0x10, 0x5a, (byte) 0xd8, 0x0a, (byte) 0xc1, 0x31,
(byte) 0x88, (byte) 0xa5, (byte) 0xcd, 0x7b, (byte) 0xbd, 0x2d,
0x74, (byte) 0xd0, 0x12, (byte) 0xb8, (byte) 0xe5, (byte) 0xb4,
(byte) 0xb0, (byte) 0x89, 0x69, (byte) 0x97, 0x4a, 0x0c,
(byte) 0x96, 0x77, 0x7e, 0x65, (byte) 0xb9, (byte) 0xf1, 0x09,
(byte) 0xc5, 0x6e, (byte) 0xc6, (byte) 0x84, 0x18, (byte) 0xf0,
0x7d, (byte) 0xec, 0x3a, (byte) 0xdc, 0x4d, 0x20, 0x79,
(byte) 0xee, 0x5f, 0x3e, (byte) 0xd7, (byte) 0xcb, 0x39, 0x48 };
private 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 };
private int Rotl(int x, int y) {
return x << y | x >>> (32 - y);
}
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);
}
private int L1(int B) {
return B ^ Rotl(B, 2) ^ Rotl(B, 10) ^ Rotl(B, 18) ^ Rotl(B, 24);
// return B^(B<<2|B>>>30)^(B<<10|B>>>22)^(B<<18|B>>>14)^(B<<24|B>>>8);
}
private int L2(int B) {
return B ^ Rotl(B, 13) ^ Rotl(B, 23);
// return B^(B<<13|B>>>19)^(B<<23|B>>>9);
}
void SMS4Crypt(byte[] Input, byte[] Output, int[] rk) {
int r, mid, x0, x1, x2, x3;
int[] x = new int[4];
int[] tmp = new int[4];
for (int i = 0; i < 4; i++) {
tmp[0] = Input[0 + 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];
// x[i]=(Input[0+4*i]<<24|Input[1+4*i]<<16|Input[2+4*i]<<8|Input[3+4*i]);
}
for (r = 0; r < 32; r += 4) {
mid = x[1] ^ x[2] ^ x[3] ^ rk[r + 0];
mid = ByteSub(mid);
x[0] = x[0] ^ L1(mid); // x4
mid = x[2] ^ x[3] ^ x[0] ^ rk[r + 1];
mid = ByteSub(mid);
x[1] = x[1] ^ L1(mid); // x5
mid = x[3] ^ x[0] ^ x[1] ^ rk[r + 2];
mid = ByteSub(mid);
x[2] = x[2] ^ L1(mid); // x6
mid = x[0] ^ x[1] ^ x[2] ^ rk[r + 3];
mid = ByteSub(mid);
x[3] = x[3] ^ L1(mid); // x7
}
// Reverse
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);
}
}
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++) {
tmp[0] = Key[0 + 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[0+4*i]<<24|Key[1+4*i]<<16|Key[2+4*i]<<8|Key[3+4*i];
}
x[0] ^= 0xa3b1bac6;
x[1] ^= 0x56aa3350;
x[2] ^= 0x677d9197;
x[3] ^= 0xb27022dc;
for (r = 0; r < 32; r += 4) {
mid = x[1] ^ x[2] ^ x[3] ^ CK[r + 0];
mid = ByteSub(mid);
rk[r + 0] = x[0] ^= L2(mid); // rk0=K4
mid = x[2] ^ x[3] ^ x[0] ^ CK[r + 1];
mid = ByteSub(mid);
rk[r + 1] = x[1] ^= L2(mid); // rk1=K5
mid = x[3] ^ x[0] ^ x[1] ^ CK[r + 2];
mid = ByteSub(mid);
rk[r + 2] = x[2] ^= L2(mid); // rk2=K6
mid = x[0] ^ x[1] ^ x[2] ^ CK[r + 3];
mid = ByteSub(mid);
rk[r + 3] = x[3] ^= L2(mid); // rk3=K7
}
// 解密时轮密钥使用顺序：rk31,rk30,...,rk0
if (CryptFlag == DECRYPT) {
for (r = 0; r < 16; r++) {
mid = rk[r];
rk[r] = rk[31 - r];
rk[31 - r] = mid;
}
}
}
public int sms4(byte[] in, int inLen, byte[] key, byte[] out, int CryptFlag) {
int point = 0;
int[] round_key = new int[ROUND];
// int[] round_key={0};
SMS4KeyExt(key, round_key, CryptFlag);
byte[] input = new byte[16];
byte[] output = new byte[16];
while (inLen >= BLOCK) {
input = Arrays.copyOfRange(in, point, point + 16);
// output=Arrays.copyOfRange(out, point, point+16);
SMS4Crypt(input, output, round_key);
System.arraycopy(output, 0, out, point, BLOCK);
inLen -= BLOCK;
point += BLOCK;
}
return 0;
}
}封装对外接口：
基于这个基本类，对其进行封装接口，主要接口如下：
private static byte[] encode16(byte[] plain, byte[] key); private static byte[] decode16(byte[] cipher, byte[] key); private static byte[] encode32(byte[] plain, byte[] key); private static byte[] decode32(byte[] cipher, byte[] key); public static byte[] encodeSMS4(byte[] plain, byte[] key); public static byte[] decodeSMS4(byte[] cipher, byte[] key); public static String decodeSMS4toString(byte[] cipher, byte[] key);
encode16(byte[], byte[])是针对16位明文和16位密钥进行加密的接口；
private static byte[] decode16(byte[] cipher, byte[] key)：是针对16位密文和16位密钥进行解密的接口；
private static byte[] encode32(byte[] plain, byte[] key)：是针对32位明文和16位密钥进行加密的接口；
private static byte[] decode32(byte[] cipher, byte[] key)：是针对32位密文和16位密钥进行解密的接口；
public static byte[] encodeSMS4(byte[] plain, byte[] key)：是针对不限字节数的明文和16位密钥进行加密的接口；
public static byte[] decodeSMS4(byte[] cipher, byte[] key)：是针对不限字节数的密文和16位密钥进行解密的接口；
public static String decodeSMS4toString(byte[] cipher, byte[] key)：是针对不限字节数的密文和16位密钥进行解密的接口；
接口方法代码：
public static byte[] encodeSMS4(String plaintext, byte[] key) {
if (plaintext == null || plaintext.equals("")) {
return null;
}
for (int i = plaintext.getBytes().length % 16; i < 16; i++) {
plaintext += ' ';
}
return SMS4.encodeSMS4(plaintext.getBytes(), key);
}
/**
* 不限明文长度的SMS4加密
*
* @param plaintext
* @param key
* @return
*/
public 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;
}
/**
* 不限明文长度的SMS4解密
*
* @param ciphertext
* @param key
* @return
*/
public 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;
}
/**
* 解密，获得明文字符串
* @param ciphertext
* @param key
* @return
*/
public static String decodeSMS4toString(byte[] ciphertext, byte[] key) {
byte[] plaintext = new byte[ciphertext.length];
plaintext = decodeSMS4(ciphertext, key);
return new String(plaintext);
}
/**
* 只加密16位明文
*
* @param plaintext
* @param key
* @return
*/
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;
}
/**
* 只解密16位密文
*
* @param plaintext
* @param key
* @return
*/
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;
}只对32位明文加密这里不做介绍，与只对16位明文的方法很类似。
而不限明文长度的加密和解密的基本算法就是基于这个只对16位进行加密和解密的基础之上的。对超过16位的明文，这里采用的是分组加密。而如果遇到像30位这样的不能被16整除长度的明文，这里采用一个补位的方式，就是将其补到对被16整除为止。原则上是只补到最小的一个能被16整除的数，当然如果你高兴，补大一些也没关系，因为补的是结束符' '。
分组加密是要把每一个16位明文加密一次，再把这些加密过的16位密文重新组合成一个新的密文。在解密的过程中也是先拆分成单个16位，再把这些解密后的若干明文重新组合成新的明文。
使用示范：
// 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 };
String newString = "Coding，你好！"; // 明文
byte[] enOut = SMS4.encodeSMS4(newString, key);
if (enOut == null) {
return;
}
System.out.println("加密结果：");
printBit(enOut);
byte[] deOut = SMS4.decodeSMS4(enOut, key);
System.out.println("
解密结果(return byte[])：");
printBit(deOut);
String deOutStr = SMS4.decodeSMS4toString(enOut, key);
System.out.println("
解密结果(return String)：
" + deOutStr);