SM4加密算法及C++语言实现
SM4 加密算法是由我国自主设计的公开的对称加密算法。该算法采用分组加密的方法，将明文转换成为密文。该算法一般用于无线互联网加密等领域。
SM4 加密算法是采用分组加密的方式，每一个分组的长度为 128bit，密钥长度也为 128bit。SM4 加解密算法和密钥扩展算法均采用非线性迭代的方式实现。输入的明文按照 128bit 进行分组，将每组按照字( 32bit )分为4个字。故输入明文简化为 X = (X0, X1, X2, X3)，其中Xi均为 32bit。
加密流程：
输入:4字明文(X0, X1, X2, X3)
迭代过程(32次){
第一次：使用前4字明文和第一轮轮密钥计算第5个字，X4=F(X0, X1, X2, X3, rk0);
第二次：使用前4字和第二轮轮密钥计算第6个字，X5=F(X1, X2, X3, X4, rk1);
...
第三十二次：使用前4字和第三十二轮轮密钥计算第36个字，X35=F(X31, X32, X33, X34, rk31);
}
反序变换：(Y0, Y1, Y2, Y3) =R (X35, X34, X33, X32)。
F函数
F函数称为轮函数，F函数的结构如下图，其中⊕代表按位异或，T函数是一个合成变换，由一个非线性变换和线性变换复合而成。
T函数
T函数的输入为一个字(32 bit)，假设输入为A = (a0, a1, a2, a3)，ai为一个字节(8bit)。T函数首先进行非线性变换，使用一个S盒来实现字节替换，得到输出B = (S(a0), S(a1), S(a2), S(a3))，之后将输输出进行一次线性变换使用循环左移变换实现，如下图。
轮密钥的生成
假设初始加密密钥为 MK=(MK0, MK1, MK2, MK3)；
将初始加密密钥与系统参数异或，(K0, K1, K2, K3)=(MK0⊕FK0, MK1⊕FK1, MK2⊕FK2, MK3⊕FK3)；其中系统参数的值是确定的。
轮密钥生成方式：
迭代过程(32次){
第一次：使用前4字(K0, K1, K2, K3)计算第5个字K4， 并将K4作为第一轮轮密钥rk0。
第二次：使用前4字(K1, K2, K3, K4)计算第6个字K5， 并将K5作为第二轮轮密钥rk1。
...
第三十二次：使用前4字(K31, K32, K33, K34)计算第36个字K35， 并将K35作为第三十二轮轮密钥rk31。
}
T`变换是将合成置换中T 中的线性变换L换成L`，其余不变。
解密算法与加密算法流程相同，只是使用的密钥使用顺序与加密的使用顺序相反。
实现代码：
#include<iostream>
//#include<bitset>
using namespace std;
/*------------------------------------- Initialize the Sbox ------------------------------------*/
const unsigned char Sbox[16][16] = {
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
};
/*------------------------------------- Definition of Parameter --------------------------------*/
const unsigned int FK0 = 0XA3B1BAC6;
const unsigned int FK1 = 0X56AA3350;
const unsigned int FK2 = 0X677D9197;
const unsigned int FK3 = 0XB27022DC;
const unsigned int CK[32] = {
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
};
/*------------------------------------- Definition of Function ---------------------------------*/
//定义循环左移函数，输入为待处理数据，以及循环左移的位数
unsigned int rol(unsigned int X, unsigned short int n){
return (X >> (sizeof(unsigned int)*8 - n) | (X << n));
}
//定义轮函数F中合成置换T
unsigned int T(unsigned int X){
unsigned char a3 = X & 0x00000ff;
unsigned char a2 = (X & 0x0000ff00) >> 8;
unsigned char a1 = (X & 0x00ff0000) >> 16;
unsigned char a0 = (X & 0xff000000) >> 24;
unsigned char b3 = Sbox[(a3 & 0xf0) >> 4][a3 & 0x0f];
unsigned char b2 = Sbox[(a2 & 0xf0) >> 4][a2 & 0x0f];
unsigned char b1 = Sbox[(a1 & 0xf0) >> 4][a1 & 0x0f];
unsigned char b0 = Sbox[(a0 & 0xf0) >> 4][a0 & 0x0f];
unsigned int B = (b0 << 24) | (b1 << 16) | (b2 << 8) | (b3);
unsigned int C = B ^ rol(B, 2) ^ rol(B, 10) ^ rol(B, 18) ^ rol(B, 24);
return C;
}
//定义密钥扩展算法中的合成置换T'
unsigned int T2(unsigned int X){
unsigned char a3 = X & 0x00000ff;
unsigned char a2 = (X & 0x0000ff00) >> 8;
unsigned char a1 = (X & 0x00ff0000) >> 16;
unsigned char a0 = (X & 0xff000000) >> 24;
unsigned char b3 = Sbox[(a3 & 0xf0) >> 4][a3 & 0x0f];
unsigned char b2 = Sbox[(a2 & 0xf0) >> 4][a2 & 0x0f];
unsigned char b1 = Sbox[(a1 & 0xf0) >> 4][a1 & 0x0f];
unsigned char b0 = Sbox[(a0 & 0xf0) >> 4][a0 & 0x0f];
unsigned int B = (b0 << 24) | (b1 << 16) | (b2 << 8) | (b3);
unsigned int C = B ^ rol(B, 13) ^ rol(B, 23);
return C;
}
int main(void){
unsigned int rk[32] = {0x0};
unsigned int X[36] = {0x0};
unsigned int K[36] = {0x0};
X[0] = 0x01234567;
X[1] = 0x89abcdef;
X[2] = 0xfedcba98;
X[3] = 0x76543210;
unsigned int MK0 = 0x01234567;
unsigned int MK1 = 0x89abcdef;
unsigned int MK2 = 0xfedcba98;
unsigned int MK3 = 0x76543210;
K[0] = MK0 ^ FK0;
K[1] = MK1 ^ FK1;
K[2] = MK2 ^ FK2;
K[3] = MK3 ^ FK3;
cout << "明文是 " << hex << X[0] << " " << X[1] << " " << X[2] << " " << X[3] << endl;
cout << "密钥是 " << hex << MK0 << " " << MK1 << " " << MK2 << " " << MK3 << endl;
for(int i = 0; i < 32; i++){
K[i+4] = K[i] ^ T2(K[i+1] ^ K[i+2] ^ K[i+3] ^ CK[i]);
rk[i] = K[i+4];
X[i+4] = X[i] ^ T(X[i+1] ^ X[i+2] ^ X[i+3] ^ rk[i]);
cout << hex << rk[i] << " \t" << X[i+4] << endl;
}
unsigned int Y0 = X[35];
unsigned int Y1 = X[34];
unsigned int Y2 = X[33];
unsigned int Y3 = X[32];
cout << "密文是 " << hex << Y0 << " " << Y1 << " " << Y2 << " " << Y3 << endl;
cout << "SUCCESS!!!!!!!!1" << endl;
return 0;
}
测试结果
参考资料
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