C语言怎么实现SM4加解密

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C语言实现SM4加解密

简介：

sm4也是一种对称加密算法，使用16字节秘钥加解密16字节数据。

先生成32个32位子秘钥，数据再配合秘钥迭代计算数据32次，取最后四次生成的32位数据，倒序组合成128位结果。

使用到3张表，系统参数表，固定参数表，和sbox表。

128位秘钥拆分成4段32位，分别异或4个系统参数得到k1到k4，k5到k6分别依赖前4组秘钥使用固定算法所得..... 过程可根据代码了解，流程比较简单。

tables.h

#ifndef _SM4_H_
#define _SM4_H_
#include <stdio.h>
#include <string.h>
const unsigned long TBL_SYS_PARAMS[4] = {
    0xa3b1bac6,
    0x56aa3350,
    0x677d9197,
    0xb27022dc
};
const unsigned long TBL_FIX_PARAMS[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
};
const unsigned char TBL_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
};
#endif

sm4_tool.c

#include "tables.h"
void four_uCh3uLong(unsigned char *in , unsigned long *out);
void uLong2four_uCh(unsigned long in , unsigned char *out);
unsigned long move(unsigned long data , int length);
unsigned long func_key(unsigned long input);
unsigned long func_data(unsigned long input);
int proc_enc_dec(char *type , unsigned char *key , unsigned char *input , unsigned char *output);
void print_hex(unsigned char *data , int len);
int hex_str2bytes(unsigned char *in ,  unsigned char *out , int *outLen);
//4字节无符号数组转无符号long型
void four_uCh3uLong(unsigned char *in , unsigned long *out)
{
    int i = 0;
    *out = 0;
    for(i = 0 ; i < 4 ; i++)
        *out = ((unsigned long)in[i] << (24-i*8)) ^ *out;
}
//无符号long型转4字节无符号数组
void uLong2four_uCh(unsigned long in , unsigned char *out)
{
    int i = 0;
    //从32位unsigned long的高位开始取
    for(i = 0 ; i < 4 ; i++)
        *(out+i) = (unsigned char )(in >> (24-i*8));
}
//左移，保留丢弃位放置尾部
unsigned long move(unsigned long data , int length)
{
    unsigned long result = 0;
    result = (data << length) ^ (data >> (32-length));
    return result;
}
//秘钥处理函数
unsigned long func_key(unsigned long input)
{
    int i = 0;
    unsigned long ulTmp = 0;
    unsigned char ucIndexList[4] = {0};
    unsigned char ucSboxValueList[4] = {0};
    uLong2four_uCh(input , ucIndexList);
    for(i = 0 ; i < 4 ; i++)
    {
        ucSboxValueList[i] = TBL_SBOX[ucIndexList[i]];
    }
    four_uCh3uLong(ucSboxValueList , &ulTmp);
    ulTmp = ulTmp ^ move(ulTmp , 13) ^ move(ulTmp , 23);
    return ulTmp;
}
//加解密数据处理函数
unsigned long func_data(unsigned long input)
{
    int i = 0;
    unsigned long ulTmp = 0;
    unsigned char ucIndexList[4] = {0};
    unsigned char ucSboxValueList[4] = {0};
    uLong2four_uCh(input , ucIndexList);
    for(i = 0 ; i < 4 ; i++)
    {
        ucSboxValueList[i] = TBL_SBOX[ucIndexList[i]];
    }
    four_uCh3uLong(ucSboxValueList , &ulTmp);
    ulTmp = ulTmp ^ move(ulTmp , 2) ^ move(ulTmp , 10) ^ move(ulTmp , 18) ^ move(ulTmp , 24);
    return ulTmp;
}
//加解密函数
int proc_enc_dec(char *type , unsigned char *key , unsigned char *input , unsigned char *output)
{
    int i = 0;
    unsigned long ulKeyTmpList[4] = {0};
    unsigned long ulKeyList[36] = {0};
    unsigned long ulDataList[36] = {0};
    /*开始生成子秘钥*/
    four_uCh3uLong(key , &(ulKeyTmpList[0]));
    four_uCh3uLong(key+4 , &(ulKeyTmpList[1]));
    four_uCh3uLong(key+8 , &(ulKeyTmpList[2]));
    four_uCh3uLong(key+12 , &(ulKeyTmpList[3]));
    ulKeyList[0] = ulKeyTmpList[0] ^ TBL_SYS_PARAMS[0];
    ulKeyList[1] = ulKeyTmpList[1] ^ TBL_SYS_PARAMS[1];
    ulKeyList[2] = ulKeyTmpList[2] ^ TBL_SYS_PARAMS[2];
    ulKeyList[3] = ulKeyTmpList[3] ^ TBL_SYS_PARAMS[3];
    for(i = 0 ; i < 32 ; i++)
    {
        //5-36为32个子秘钥
        ulKeyList[i+4] = ulKeyList[i] ^ func_key(ulKeyList[i+1] ^ ulKeyList[i+2] ^ ulKeyList[i+3] ^ TBL_FIX_PARAMS[i]);
    }
    /*生成32轮32位长子秘钥结束*/
    /*开始处理加解密数据*/
    four_uCh3uLong(input , &(ulDataList[0]));
    four_uCh3uLong(input+4 , &(ulDataList[1]));
    four_uCh3uLong(input+8 , &(ulDataList[2]));
    four_uCh3uLong(input+12 , &(ulDataList[3]));
    if(strcmp(type , "1") == 0)
    {
        //加密
        for(i = 0 ; i < 32 ; i++)
        {
            ulDataList[i+4] = ulDataList[i] ^ func_data(ulDataList[i+1] ^ ulDataList[i+2] ^ ulDataList[i+3] ^ ulKeyList[i+4]);
        }
    }
    else if(strcmp(type , "2") == 0)
    {
        //解密
        for(i = 0 ; i < 32 ; i++)
        {
            ulDataList[i+4] = ulDataList[i] ^ func_data(ulDataList[i+1] ^ ulDataList[i+2] ^ ulDataList[i+3] ^ ulKeyList[35-i]);
        }
    }
    uLong2four_uCh(ulDataList[35] , output);
    uLong2four_uCh(ulDataList[34] , output+4);
    uLong2four_uCh(ulDataList[33] , output+8);
    uLong2four_uCh(ulDataList[32] , output+12);
    return 0;
}
//无符号字符数组转16进制打印
void print_hex(unsigned char *data , int len)
{
    int i = 0;
    char alTmp[16] = {'0','1','2','3','4','5','6','7','8','9','a','b','c','d','e','f'};
    for(i = 0 ; i < len ; i++)
    {
        printf("%c" , alTmp[data[i]/16]);
        printf("%c" , alTmp[data[i]%16]);
//        putchar(' ');
    }
    putchar('
');
}
//16进制数组转无符号字符数组
int hex_str2bytes(unsigned char *in ,  unsigned char *out , int *outLen)
{
    int i = 0 , j = 0;
    int num = 0;
    int tmp = 0;
    for (i = 0 ; i < strlen((char *)in) ; i++)
    {
        if(in[i] < 58 && in[i] > 47) //0-9
            tmp = in[i]-48;
        else if(in[i] < 71 && in[i] > 64) //A-F
            tmp = 10+in[i]-65;
        else if(in[i] < 103 && in[i] > 96) //a-f
            tmp = 10+in[i]-97;
        else
        {
            printf("Invalid arg!
");
            return -1;
        }
        if(i%2 == 0)
            num = tmp*16;
        else
        {
            num += tmp;
            out[j++] = num;
        }
    }
    *outLen = j;
    return 0;
}
int main(int argc , char **argv)
{
    unsigned char alResult[16] = {0};
    unsigned char alKey[16] = {0};
    int ilKeyLen = 0;
    unsigned char alData[16] = {0};
    int ilDataLen = 0;
    if(argc != 4 || strlen(argv[2]) != 32 || strlen(argv[3]) != 32 || 
        (strcmp(argv[1] , "1") != 0 && strcmp(argv[1] , "2") != 0) )
    {
        printf("Usage: ./sm4_tool  [1/2]  hex32_key  hex32_data
1:encrypt , 2:decrypt
");
        return -1;
    }
    if(hex_str2bytes((unsigned char *)argv[2] , alKey , &ilKeyLen))
        return -1;
    if(hex_str2bytes((unsigned char *)argv[3] , alData, &ilDataLen))
        return -1;
    proc_enc_dec(argv[1] , alKey , alData , alResult);
    print_hex(alResult , 16);
    return 0;
}

Makefile：

TARGET = sm4_tool
DEPEND = sm4_tool.o
CC = gcc -g -Wall
RM = rm -f
.c.o :
    $(CC) -c $^ -o $@
$(TARGET) : $(DEPEND)
    $(CC) $^ -o $@
.PHONY : clean
clean :
    $(RM) $(TARGET) *.o

这里main函数参数只针对16字节秘钥和16字节数据测试用。

加密：./sm4_tool 1 0123456789abcdeffedcba9876543210 0123456789abcdeffedcba9876543210

结果：

681edf34d206965e86b3e94f536e4246

解密：./sm4_tool 2 0123456789abcdeffedcba9876543210 681edf34d206965e86b3e94f536e4246

结果：

0123456789abcdeffedcba9876543210

C语言文件加解密

#include <stdio.h>
#include <stdlib.h>
#define N 30 //文件名字的长度
/**************************************************************************/
//函数功能:解密字符串
//参数：
//		src_file_text:要解密的字符串。 length:字符串的长度  
//   	password: 解密密码
//返回值: 解密后的字符串的首地址
/**************************************************************************/
char * file_text_decrypt(char * src_file_text,unsigned long int length,unsigned int password)
{
	char * file_text=NULL;
	char * result_text=NULL;
	unsigned long int i;
	result_text=file_text=src_file_text;
	for(i=0;i<length;i++)
	{
		*file_text++ = (*src_file_text++)-password;
	}
	return result_text;
}
/**************************************************************************/
//函数功能:将字符串保存到目的文件中
//参数：
//		text:要保存的字符串首地址 。   file_name :目的文件的名字
//    	length:字符串的长度
/**************************************************************************/
void save_file(char* text,unsigned long int length,char * file_name)
{
	FILE  *dest_fp;
	dest_fp=fopen(file_name,"wb+");
	if(dest_fp==NULL)
	{
		printf("open %s faild
",file_name);
	}
	if(fwrite(text,length,1,dest_fp)<=0)
	{
		printf("write %s error
",file_name);
	}
	else
	{
		printf("save sucess
");
	}
	fclose(dest_fp);
}
/**************************************************************************/
//函数功能:加密字符串
//参数：
//		src_file_text:要加密的字符串。 length:字符串的长度  
//   	password: 加密密码
// 返回值: 加密后的字符串的首地址
/**************************************************************************/
char * file_text_encrypt(char * src_file_text,unsigned long int length,unsigned int password)
{
	char * file_text=NULL;
	char * result_text=NULL;
	unsigned int i;
	result_text=file_text=src_file_text;
	for(i=0;i<length;i++)
	{
		*file_text++ = (*src_file_text++)+password;
	}
	return result_text;
}
/**************************************************************************/
//	函数功能:读出文件内容
//	参数：
//		file_length:整型指针，此地址中保存文件字节数。 
// 		src_file_name:文件名字，从此文件中读取内容。 
// 	返回值:读出字符串的首地址
/**************************************************************************/
char * read_src_file(unsigned long int *file_length,char *src_file_name)
{
	unsigned long int FILE_SIZE=0;
	char *src_file_text=NULL;
	FILE *fp;
	fp=fopen(src_file_name,"rb");
	if(fp==NULL)
	{
		printf("open %s faild
",src_file_name);
		return 0;
	}
	fseek(fp,0,SEEK_END);
	FILE_SIZE=ftell(fp);
	*file_length=FILE_SIZE;
	rewind(fp);
	src_file_text=(char *)malloc(FILE_SIZE);
	if(fread(src_file_text,FILE_SIZE,1,fp)==0)
	{
		printf("read from src_file faild
");
		return NULL;
	}
	fclose(fp);// 关闭文件
	return src_file_text ;
}
/**************************************************************************/
//函数功能:获取 目的文件和源文件的名字
//参数： 
//		src_file_name:源文件名字。 
// 		dest_file_name:目的文件的名字
/**************************************************************************/
void get_file_name(char * dest_file_name,char * src_file_name)
{
	printf("请输入你的原文件名称(%d个字符):",N);
	gets(src_file_name);
	printf("请输入你的目的文件名称(%d个字符):",N);
	gets(dest_file_name);
}
/**************************************************************************/
//
//	函数功能:打印帮助信息
//
/**************************************************************************/
void print_help()
{
	printf("********1:加密文件***********
");
	printf("********2:解密文件***********
");
	printf("********3:退出程序***********
");
}
int main()
{
	char src_file_name[N]="";			//源文件的名字
	char dest_file_name[N]="";			//目标文件的名字
	char *src_file_text=NULL;			//指向malloc的空间，其存入的是 源文件的内容
	unsigned long int file_length=0;	//保存 源文件的长度
	unsigned int password=0;
	int menu=0;
	while(1)
	{
		print_help();
		scanf("%d",&menu);
		getchar();						//提取输入缓存区中的'
'
		switch(menu)
		{
	    	case  1 :
				{
					get_file_name(dest_file_name,src_file_name);			// 获取原文件和目的文件名
					src_file_text=read_src_file(&file_length,src_file_name);// 从源文件中读取数据
					printf("please input your unsigned int passworld:");
					scanf("%d",&password);// 输入密码 必须是无符号整型的
					getchar();
					src_file_text=file_text_encrypt(src_file_text,file_length,password);// 给字符串加密返回加密后的字符串的首地址
					save_file(src_file_text,file_length,dest_file_name);// 将字符串保存到目的文件中
					if(src_file_text!=NULL)
						free(src_file_text);//回收资源
					break;
				}
			case 2:
				{
					get_file_name(dest_file_name,src_file_name);			// 获取原文件和目的文件名
					src_file_text=read_src_file(&file_length,src_file_name);// 从源文件中读取数据
					printf("please input your passworld:");
					scanf("%d",&password);	// 获取密码
					getchar();
					src_file_text=file_text_decrypt(src_file_text,file_length,password);// 解密字符串，返回解密后的字符串的首地址
					save_file(src_file_text,file_length,dest_file_name);// 将解密后的字符串保存到目的文件中
					if(src_file_text!=NULL)
						free(src_file_text);//回收资源
					break;
				}
			case 3:
				{
					return 0;				// 退出 程序
				}
			default :
				{
					printf("请输入一个正确的选项 
");
				}
		}
	}
	return 0;
}

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