c_jiami.c

纯Ｃ写的加密程序

//原作者:Niti的朋友
//来源Niti Cheung 
//电邮:[e-mail]
//Blog:www.naio.net
//日期:2003-3-16
//请保留版权
//此代码为免费代码,您可以保留版权的情况下,在教学和演示甚至无限制编译此程序
#include <stdio.h>
#define MAX_KEY 19             //密码变换后的长度
int main(void)
{
 char FileName[40];
 FILE *inf_file, *newfile;
 char buffer;
 
 char Key[MAX_KEY];         //存储密码的字符数组
 char B[32];                //定义新数组用于转储
 char C[10];                 //存储经M序列变换后得到的生成序列
 char SwitchTab[256] = { 
       0xc6, 0x37, 0x87, 0x47,0xdf, 0x46, 0x6,0xac,0xf3,0xe0, 0x86, 0x42, 0x1f, 0x8d, 0x4a, 0x97,
       0x5c,0xd8, 0x6c, 0x27, 0x5f, 0x65, 0x84,0xff, 0x2a,0xbd,0xda, 0xa, 0x39,0xba,0xd7,0xfc,
       0x8b, 0x2f,0xc9, 0x92, 0x93,  0x3, 0x8f, 0x3c,0xb3,0xaa,0xae,0xef,0xe7, 0x7d,0xe3,0xa1,
       0xb0, 0x8c,0xc2,0xcc, 0x71, 0x99,0xa0, 0x59, 0x80,0xd1,0xf8,0xde, 0x4e, 0x82,0xdb,0xa7,
       0x60,0xc8, 0x32, 0x51, 0x41, 0x16, 0x55,0xfa,0xd5, 0x43, 0x9d,0xcb, 0x62,0xce,  0x2,0xb8,
       0xc5,0xed,0xf0, 0x2e,0xf2, 0x3f,0xeb, 0x45, 0x56, 0x4c, 0x1b, 0x63, 0x54, 0x34, 0x75, 0xc,
       0xfd, 0xe, 0x5a, 0x4f,0xc4, 0x24,0xc3,0xa8,0xa4, 0x6f,0xd0,  0x7,0xf5, 0x33,  0x9, 0x7a,
       0xe5,0xca,0xf4,  0x8,0xd9, 0x29, 0x73,0xaf, 0x3b, 0x9b, 0x5d,0xe2,0xf1, 0xf,0xcf,0xdd,
       0x2c, 0x30,0xc1, 0x3e, 0x5, 0x89,0xb4, 0x81,0xbc, 0x8a, 0x17, 0x23,0xb6, 0x25, 0x61,0xc7,
       0xf6,0xe8,  0x4, 0x3d,0xd2, 0x52,0xf9, 0x78, 0x94, 0x1e, 0x7b,0xb1, 0x1d, 0x15, 0x40, 0x4d,
       0xfe,0xd3, 0x53, 0x50, 0x64, 0x90,0xb2, 0x35,0xdc,0xcd, 0x3a,0xd6,0xe9,0xa9,0xbe, 0x67,
       0x8e, 0x7c, 0x83,0x26, 0x28,0xad, 0x14, 0x6a, 0x36, 0x95,0xbf, 0x5e,0xa6, 0x57, 0x1a, 0x70,
       0x5b, 0x77,0xa2, 0x12, 0x31, 0x9a,0xbb, 0x9c, 0x7e, 0x2d,0xb7,  0x1, 0x44, 0x2b, 0x48, 0x58,
       0xf7, 0x13,0xab, 0x96, 0x74,0xc0, 0x9f, 0x10,0xe6,0xa3, 0x85, 0x6b, 0x98,0xec, 0x21, 0x19,
       0xee, 0x7f, 0x79,0xe1, 0x66, 0x6d, 0x18,0xb9, 0x49, 0x11, 0x88, 0x6e, 0x1c,0xa5, 0x72, 0xd,
       0x38,0xea, 0x68, 0x20, 0xb, 0x9e,0xd4, 0x76,0xe4, 0x69, 0x22,  0x0,0xfb,0xb5, 0x4b, 0x91
      };  //置换表
 int n; //计数器
 char s, y;
 char COEF = 0x10;    //M序列生成器的系数
 char t;
 int D, d;
 int i, j;
 
 printf("请输入要加密的文件名：");
 scanf("%s", FileName);
  
 inf_file = fopen(FileName,"rb");

 if (inf_file == NULL)
  printf("文件打开失败 请检查文件是否存在或文件名是否输入正确\n");
 
 
 printf("\n 请输入10位字符密码:");
 for(n = 0; n < 10; n++)
  scanf( "%c", &Key[n]);
 
 n = 0;
 
 do{
  Key[n] = SwitchTab[Key[n]];         //从置换表中对密钥进行简单置换
  n++;
 }while(n < 10);

 for(n = 10; n < 19; n++)              // 生成 19字节的密钥长度
  Key[n] = (Key[n-10] ^ Key[n-7] ^ Key[n-2] ^ Key[n-1] ^ n) << 3; //运算符优先级问题


 s = (COEF & 0x80)? 1 : 0; //提取M序列系数的最高位
 COEF = (COEF << 1) | 1;    //将其左移与上面s的最低位一起构成9bit


 C[0] = 1;                  //初始化生成序列的第一位 这一位是给定的
                            //所以c 数组应是10 个而不是 9 个
 

 if ( (newfile = fopen("加密文件.txt", "wb+") ) == NULL)
  printf("\n创建文件失败");


 while ( fread(&buffer, sizeof(char), 1, inf_file) == 1  )
 {

  
  for (n = 0; n < 9; n++)    //生成9 位序列
  {
   y = (Key[16] & 0X80)? 1 : 0;    //提出8位密钥的最高位
   Key[16] = (Key[16] << 1) | C[n]; //将其左移与上面1bit构成9bit

   t = Key[16] & COEF;              //M序列的计算 将系数与初始值相乘
   t ^= ((t << 1) ^ (t << 2) ^ (t << 3) ^ (t << 4) ^ (t << 5) ^ (t << 6) ^ (t << 7)); //将相乘结果模2加
  
   if (t & 0X80)                  //提取生成的1bit
       C[n + 1] = 1 ^ (y & s);  //将结果与先前提取的最高位进行模2运算
   else 
    C[n + 1] = 0 ^ (y & s);
  }

  D = 2 * 2 * C[1] + 2 * C[2] +  C[3];//此处数组位置比题目要求大1是因为将C[0]用于固定常量 1 了
  d = 2 * 2 * 2 * C[5] + 2 * 2 * C[6] + 2 * C[7] + C[8]; 


 
 
  for (n = 0; n < 16; n++)              //将密钥前16字节拷至B数组以方便下面的数据处理
   B[n] = Key[n];

  for (j = 16,i = 0; i < 16; i++, j++)
   B[j] = (B[i] + B[i + 11] + B[i + 13] + B[i + 14]) ; //模28的附加式发生器 (16,5,3,2)
  
  // 经以上循环处理后变换后的密钥部分是从B[16] -- B[31] 而不是B[0] -- B[15]

  for (n = 0; n < D; n++)              //     (钟控：进动D拍)
  {
   y = (B[16] & 0X80)? 1 : 0;      //   先对第一字节的最高位提取并保存

   for (j = 16; j < 31; j++)         //  然后对后面的各位依次左移1bit 因为是循环移位 最后一个字节并没处理
   {
    s = (B[j + 1] & 0X80)? 1 : 0;
    B[j] = (B[j] << 1) | s;
   }
  
   B[31] = (B[31] << 1) | y;       //  用前面所存储的最高位对最后一字节进行处理
  }

  for (j = 16; j < 32; j++)          //  右 环 移 d 字 节
   B[((j + d) % 16)] = B[j];         
    
  B[0] ^= Key[17];                    //对密钥的首字节和末字节进行模2处理
  B[15] ^= Key[18];
   
  for (j = 0; j < 16; j++)
   B[j] = SwitchTab[B[j]];          //对B从置换表进行固定字节的替换
    
  Key[17] = (B[0] & B[1] & B[2] & B[3]) | (B[4] & B[5] & B[6] & B[7]);  //重新设置m1和m2的值
     Key[18] = (B[8] & B[9] & B[10] & B[11]) | (B[12] & B[13] & B[14] & B[15]);
     
  buffer ^= (Key[17] ^ Key[18]);
  
  if (fwrite(&buffer, sizeof(char), 1, newfile) != 1)
   printf("\n文件写入错误");

  


 }
 fclose(inf_file);
 fclose(newfile);
 
 return 0;
 
}