c - 在 C 中执行 main() 一半后输出消失

Question

我有一个文本文件“my.txt”。我想从文本文件中读取前 16 个字节，然后对数据执行密钥扩展和密码算法的 aes 操作。在此之后，接下来的 16 个字节将被加密。我运行以下代码，但在执行过程中，输入十六进制的密钥后，输出屏幕就消失了。我不明白为什么会这样？相同的文件读取工作在单独的程序中成功运行，但在将其合并到我的 AES（高级加密标准）程序中后，程序的文件部分不执行。事实上，从用户那里获取密钥后屏幕会消失。请帮助我。

    #include<stdio.h>
    #include<stdlib.h>
    #include<conio.h>
    #include<string.h>

    // The number of columns comprising a state in AES. This is a constant in AES. //Value=4

    #define Nb 4

    // The number of rounds in AES Cipher. It is simply initiated to zero. The actual value is recieved in the program.

    int Nr=0;

    // The number of 32 bit words in the key. It is simply initiated to zero. The actual value is recieved in the program.

    int Nk=0;

    // in - it is the array that holds the plain text to be encrypted.

    // out - it is the array that holds the output CipherText after encryption.

    // state - the array that holds the intermediate results during encryption.

    char in[64], out[16], state[4][4];

    // The array that stores the round keys.

    char RoundKey[240];

    // The Key input to the AES Program

    char Key[32];

    int getSBoxValue(int num)
    {

     int sbox[256] =   {

//0     1    2      3     4    5     6     7      8    9     A      B    C     D     E     F

0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76, //0

0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0, //1

0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15, //2

0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75, //3

0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84, //4

0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf, //5

0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8, //6

0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2, //7

0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73, //8

0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb, //9

0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79, //A

0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08, //B

0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a, //C

0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e, //D

0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf, //E

0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 }; //F

    return sbox[num];
    }

    // The round constant word array, Rcon[i], contains the values given by

    // x to th e power (i-1) being powers of x (x is denoted as {02}) in the field GF(28)

    // Note that i starts at 1, not 0).

    int Rcon[255] = {

0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,

0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39,

0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,

0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,

0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef,

0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,

0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b,

0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,

0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94,

0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,

0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,

0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f,

0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,

0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63,

0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd,

0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb  };

    // This function produces Nb(Nr+1) round keys. The round keys are used in each round to encrypt the states.

    void KeyExpansion()
    {

    int i,j;

    char temp[4],k;

    // The first round key is the key itself.

    for(i=0;i<Nk;i++)
    {

     RoundKey[i*4]=Key[i*4];

     RoundKey[i*4+1]=Key[i*4+1];

     RoundKey[i*4+2]=Key[i*4+2];

     RoundKey[i*4+3]=Key[i*4+3];

     }

     // All other round keys are found from the previous round keys.

     while (i < (Nb * (Nr+1)))
     {
     for(j=0;j<4;j++)
     {
        temp[j]=RoundKey[(i-1) * 4 + j];
     }

     if (i % Nk == 0)
     {

        // This function rotates the 4 bytes in a word to the left once.

        // [a0,a1,a2,a3] becomes [a1,a2,a3,a0]

        // Function RotWord()

        {

            k = temp[0];

            temp[0] = temp[1];

            temp[1] = temp[2];

            temp[2] = temp[3];

            temp[3] = k;

        }

        // SubWord() is a function that takes a four-byte input word and

        // applies the S-box to each of the four bytes to produce an output word.

        // Function Subword()

        {

            temp[0]=getSBoxValue(temp[0]);

            temp[1]=getSBoxValue(temp[1]);

            temp[2]=getSBoxValue(temp[2]);

            temp[3]=getSBoxValue(temp[3]);

            }

            temp[0] =  temp[0] ^ Rcon[i/Nk];
            }

            else if (Nk > 6 && i % Nk == 4)
            {

            // Function Subword()
            {
            temp[0]=getSBoxValue(temp[0]);

            temp[1]=getSBoxValue(temp[1]);

            temp[2]=getSBoxValue(temp[2]);

            temp[3]=getSBoxValue(temp[3]);

            }
            }

            RoundKey[i*4+0] = RoundKey[(i-Nk)*4+0] ^ temp[0];

            RoundKey[i*4+1] = RoundKey[(i-Nk)*4+1] ^ temp[1];

            RoundKey[i*4+2] = RoundKey[(i-Nk)*4+2] ^ temp[2];

            RoundKey[i*4+3] = RoundKey[(i-Nk)*4+3] ^ temp[3];

             i++;

            }

             }

           // This function adds the round key to state.

           // The round key is added to the state by an XOR function.

           void AddRoundKey(int round)
           {

           int i,j;

           for(i=0;i<4;i++)
           {

           for(j=0;j<4;j++)
           {
           state[j][i] ^= RoundKey[round * Nb * 4 + i * Nb + j];
           }
           }
           }

           // The SubBytes Function Substitutes the values in the

           // state matrix with values in an S-box.

           void SubBytes()

           {

           int i,j;

           for(i=0;i<4;i++)

           {

           for(j=0;j<4;j++)

           {

           state[i][j] = getSBoxValue(state[i][j]);

           }

           }

           }

         // The ShiftRows() function shifts the rows in the state to the left.

         // Each row is shifted with different offset.

         // Offset = Row number. So the first row is not shifted.

        void ShiftRows()

         {

        char temp;

// Rotate first row 1 columns to left

temp=state[1][0];

state[1][0]=state[1][1];

state[1][1]=state[1][2];

state[1][2]=state[1][3];

state[1][3]=temp;

// Rotate second row 2 columns to left

temp=state[2][0];

state[2][0]=state[2][2];

state[2][2]=temp;

temp=state[2][1];

state[2][1]=state[2][3];

state[2][3]=temp;

// Rotate third row 3 columns to left

temp=state[3][0];

state[3][0]=state[3][3];

state[3][3]=state[3][2];

state[3][2]=state[3][1];

state[3][1]=temp;

 }

      // xtime is a macro that finds the product of {02} and the argument to xtime modulo {1b}

      #define xtime(x)   ((x<<1) ^ (((x>>7) & 1) * 0x1b))
      void MixColumns()

       {

       int i;

       char Tmp,Tm,t;

       for(i=0;i<4;i++)

       {

        t=state[0][i];

         Tmp = state[0][i] ^ state[1][i] ^ state[2][i] ^ state[3][i] ;

         Tm = state[0][i] ^ state[1][i] ; Tm = xtime(Tm); state[0][i] ^= Tm ^ Tmp ;

         Tm = state[1][i] ^ state[2][i] ; Tm = xtime(Tm); state[1][i] ^= Tm ^ Tmp ;

         Tm = state[2][i] ^ state[3][i] ; Tm = xtime(Tm); state[2][i] ^= Tm ^ Tmp ;

         Tm = state[3][i] ^ t ; Tm = xtime(Tm); state[3][i] ^= Tm ^ Tmp ;

          }

         }

       // Cipher is the main function that encrypts the PlainText.

      void Cipher()

         {

int i,j,round=0;

//Copy the input PlainText to state array.

for(i=0;i<4;i++)

{

    for(j=0;j<4;j++)

    {

        state[j][i] = in[i*4 + j];

    }

}

// Add the First round key to the state before starting the rounds.

AddRoundKey(0);

// There will be Nr rounds.

// The first Nr-1 rounds are identical.

// These Nr-1 rounds are executed in the loop below.

for(round=1;round<Nr;round++)

{

    SubBytes();

    ShiftRows();

    MixColumns();

    AddRoundKey(round);

}

// The last round is given below.

// The MixColumns function is not here in the last round.

SubBytes();

ShiftRows();

AddRoundKey(Nr);

// The encryption process is over.

// Copy the state array to output array.

for(i=0;i<4;i++)

{

    for(j=0;j<4;j++)

    {

        out[i*4+j]=state[j][i];

    }

    }

    }



    int main()
    {
    printf("\n*******************AES Encryption Implementation******************\n");
    printf("\n******************************************************************\n");

    int i;

    // Receive the length of key here.

    while(Nr!=128 && Nr!=192 && Nr!=256)

    {

    printf("\nEnter the length of Key  (128, 192 or 256 only): ");

    scanf("%d",&Nr);

     }

    // Calculate Nk and Nr from the received value.

    Nk = Nr / 32;

    Nr = Nk + 6;

    printf("\nEnter the Key in hexadecimal: \n");

    for(i=0;i<Nk*4;i++)
    {
    scanf("%x",&Key[i]);
    }

   char ch, file_name[25];
   FILE *fp;

   printf("Enter the name of file you wish to see\n");
   gets(file_name);

   fp = fopen(file_name,"r"); // read mode

   if( fp == NULL )
   {
   perror("Error while opening the file.\n");
   exit(EXIT_FAILURE);
   }

   printf("The contents of %s file are :\n", file_name);

   char sig[64];

   int j=0;
   int c;
   char *pstr=in;
   printf("The contents of %s file are :\n", file_name);
   for (i=1;i<=(sizeof(sig)/16);i++)
   {  
   while(j<16*i)
   {
          fscanf(fp,"%c",&sig[j]);
          sprintf(pstr,"%02x",sig[j]);
          sscanf(pstr,"%02x",&in[j]); 
          pstr+=2;    
          printf("\nPlaintext:\n%02x ",in[j]);            
          j++;
          }            

          // The KeyExpansion routine must be called before encryption.


          KeyExpansion();


          // The next function call encrypts the PlainText with the Key using AES    algorithm.


           Cipher();

// Output the encrypted text.


           printf("\nText after encryption:\n");

           for(c=0;c<Nk*4;c++)
           {
           printf("\n%02x ",out[c]);
           }
           }

           fclose(fp);

           printf("\n\n");     
           getche();
            }

score 0 · Accepted Answer

for(i=0;i<Nk*4;i++)
{
scanf("%x",&Key[i]);
}

在获取文件名之前，您必须使用标准输入中的换行符。输入数字时，每行输入 1 个十六进制数字。所以在读取了所有 Nk*4 位之后，有一个换行符等待被消耗。获取换行符的下一条语句是gets函数。它假定它已读取文件名。文件名显然不存在，因为它是空的。解决方法是在获取文件名之前使用换行符（参见代码片段）

我不确定会Key进行什么样的手术。但它必须是一个unsigned int如果它要接受十六进制数字。gets不推荐。改为使用fgets。

这是您可以发布的示例片段。

#include <stdio.h>
#include <string.h>

int main(void)
{
    unsigned int hex[32]={0} ;
    char line[BUFSIZ] = "";
    char filename[64] = "";
    int i;

    printf("Enter 4 hex digits:");
    for (i = 0; i < 4; ++i) {
        printf(">");
        scanf("%x", &hex[i]);
    }    

    printf("The hex digits are:");    
    for (i = 0; i < 4; ++i)
        printf("%x", hex[i]);
    /* Consume newline */
    fgets(line, sizeof line, stdin);

    printf("Enter filename with full path");
    if (fgets(filename, sizeof filename, stdin)) {
        size_t len = strlen(filename); /* has a newline in the end */
        filename[len - 1] = '\0';

        printf("Filename was %s\n", filename);
    } else {
       puts("Cannot read filename");
    }
    return 0;
}

score 0 · Accepted Answer

我不太了解您要描述的问题，但是正如您所描述的，这听起来像是在遍历Key[]数组时出现了分段错误。它是什么类型的数据？

编辑（作为OP更新的问题）：

scanf("%x", ...)期望unsigned int *（通常为 32 个字节长）作为一种类型，而您提供char *（1 个字节）。既然你正在使用char Key[32]，我认为只使用类似的东西unsigned int Key就足够了。

c - 在 C 中执行 main() 一半后输出消失

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