SM4对称算法
此算法是一个分组算法,用于无线局域网产品。该算法的分组长度为128比特,密钥长度为128比特。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。
此算法采用非线性迭代结构,每次迭代由一个轮函数给出,其中轮函数由一个非线性变换和线性变换复合而成,非线性变换由S盒所给出。其中rki为轮密钥,合成置换T组成轮函数。轮密钥的产生与上图流程类似,由加密密钥作为输入生成,轮函数中的线性变换不同,还有些参数的区别。SM4算法的具体描述和示例见SM4标准。
C语言代码:
`#include<stdio.h>
#define u8 unsigned char
#define u32 unsigned long
// S盒
const u8 Sbox[256] = {
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
};
// 密钥扩展算法的常数FK
const u32 FK[4] = {
0xa3b1bac6, 0x56aa3350, 0x677d9197, 0xb27022dc
};
// 密钥扩展算法的固定参数CK
const u32 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
};
u32 functionB(u32 b); // 查S盒的函数B
u32 loopLeft(u32 a, short length); // 循环左移函数
u32 functionL1(u32 a); // 线性变换L
u32 functionL2(u32 a); // 线性变换L'
u32 functionT(u32 a, short mode); // 合成变换T
void extendFirst(u32 MK[], u32 K[]); // 密钥扩展算法第一步
void extendSecond(u32 RK[], u32 K[]); // 密钥扩展算法第二步
void getRK(u32 MK[], u32 K[], u32 RK[]); // 轮密钥获取算法
void iterate32(u32 X[], u32 RK[]); // 迭代算法
void reverse(u32 X[], u32 Y[]); // 反转函数
void encryptSM4(u32 X[], u32 RK[], u32 Y[]); // 加密算法
void decryptSM4(u32 X[], u32 RK[], u32 Y[]); // 解密算法
//查S盒的函数B
u32 functionB(u32 b) {
u8 a[4];
short i;
a[0] = b / 0x1000000;
a[1] = b / 0x10000;
a[2] = b / 0x100;
a[3] = b;
b = Sbox[a[0]] * 0x1000000 + Sbox[a[1]] * 0x10000 + Sbox[a[2]] * 0x100 + Sbox[a[3]];
return b;
}
//循环左移算法
u32 loopLeft(u32 a, short length) {
short i;
for(i = 0; i < length; i++) {
a = a * 2 + a / 0x80000000;
}
return a;
}
//密钥线性变换函数L
u32 functionL1(u32 a) {
return a ^ loopLeft(a, 2) ^ loopLeft(a, 10) ^ loopLeft(a, 18) ^ loopLeft(a, 24);
}
//密钥线性变换函数L'
u32 functionL2(u32 a) {
return a ^ loopLeft(a, 13) ^ loopLeft(a, 23);
}
/*
合成变换T
参数: u32 a short mode:1表示明文的T,调用L;2表示密钥的T,调用L'
*/
u32 functionT(u32 a, short mode) {
return mode == 1 ? functionL1(functionB(a)) : functionL2(functionB(a));
}
/*
密钥扩展算法第一步
参数: MK[4]:密钥 K[4]:中间数据,保存结果 (FK[4]:常数)
*/
void extendFirst(u32 MK[], u32 K[]) {
int i;
for(i = 0; i < 4; i++) {
K[i] = MK[i] ^ FK[i];
}
}
/*
密钥扩展算法第二步
参数: RK[32]:轮密钥,保存结果 K[4]:中间数据 (CK[32]:固定参数)
*/
void extendSecond(u32 RK[], u32 K[]) {
short i;
for(i = 0; i <32; i++) {
K[(i+4)%4] = K[i%4] ^ functionT(K[(i+1)%4] ^ K[(i+2)%4] ^ K[(i+3)%4] ^ CK[i], 2);
RK[i] = K[(i+4)%4];
}
}
/*
密钥扩展算法
参数: MK[4]:密钥 K[4]:中间数据 RK[32]:轮密钥,保存结果
*/
void getRK(u32 MK[], u32 K[], u32 RK[]) {
extendFirst(MK, K);
extendSecond(RK, K);
}
/*
迭代32次
参数: u32 X[4]:迭代对象,保存结果 u32 RK[32]:轮密钥
*/
void iterate32(u32 X[], u32 RK[]) {
short i;
for(i = 0; i < 32; i++) {
X[(i+4)%4] = X[i%4] ^ functionT(X[(i+1)%4] ^ X[(i+2)%4] ^ X[(i+3)%4] ^ RK[i], 1);
}
}
/*
反转函数
*/
void reverse(u32 X[], u32 Y[]) {
short i;
for(i = 0; i < 4; i++){
Y[i] = X[4 - 1 - i];
}
}
/*
加密算法
参数: u32 X[4]:明文 u32 RK[32]:轮密钥 u32 Y[4]:密文,保存结果
*/
void encryptSM4(u32 X[], u32 RK[], u32 Y[]) {
iterate32(X, RK);
reverse(X, Y);
}
/*
解密算法
参数: u32 X[4]:密文 u32 RK[32]:轮密钥 u32 Y[4]:明文,保存结果
*/
void decryptSM4(u32 X[], u32 RK[], u32 Y[]) {
short i;
u32 reverseRK[32];
for(i = 0; i < 32; i++) {
reverseRK[i] = RK[32-1-i];
}
iterate32(X, reverseRK);
reverse(X, Y);
}
/*
测试数据:
明文: 01234567 89abcdef fedcba98 76543210
密钥: 01234567 89abcdef fedcba98 76543210
密文: 681edf34 d206965e 86b3e94f 536e4246
*/
int main(void) {
u32 X[4]; // 明文
u32 MK[4]; // 密钥
u32 RK[32]; // 轮密钥
u32 K[4]; // 中间数据
u32 Y[4]; // 密文
short i; // 临时变量
printf("明文:");
scanf("%8x%8x%8x%8x", &X[0], &X[1], &X[2], &X[3]);
printf("密钥:");
scanf("%8x%8x%8x%8x", &MK[0], &MK[1], &MK[2], &MK[3]);
printf("**************生成轮密钥*****************\n");
getRK(MK, K, RK);
for(i = 0; i < 32; i++) {
printf("[%2d]:%08x ", i, RK[i]);
if(i%4 == 3) printf("\n");
}
printf("************** 生成密文 *****************\n");
encryptSM4(X, RK, Y);
printf("%08x %08x %08x %08x\n", Y[0], Y[1], Y[2], Y[3]);
printf("************** 生成明文 *****************\n");
decryptSM4(Y, RK, X);
printf("%08x %08x %08x %08x\n", X[0], X[1], X[2], X[3]);
return 0;
}
`