Question

我正在开发一个程序，将加密的密码与测试用相同Salt值加密的单词进行比较。 Salt是用于crypt（）函数的2字符密码，用于进一步卷积输入，并保存为加密密码的前2位数字。预期结果是密码/ Salt组合，加密到与我正在寻找的密码相同的值 - 等效密码。但是，Salt无法正确打印，因为在从加密密码读取2个字符后会出现其他（不可读）信息。虽然程序运行时没有出现错误，但无论使用什么密码，它都会产生相同的结果，编译时会出现2个警告：

Crack1.c:54:27: warning: implicit declaration of function 'crypt' is invalid    in
      C99 [-Wimplicit-function-declaration]
            *decyphered = crypt(wordtest, salt);
                          ^
Crack1.c:60:53: warning: comparison of array 'wordtest' not equal to a null
      pointer is always true [-Wtautological-pointer-compare]
        while(!memcmp(enc1, decyphered, (k + 2)) && wordtest != NULL);
                                                ^~~~~~~~    ~~~~
2 warnings generated.

运行时：

Test

Print encrypted text: 50zPJlUFIYY0o
Encrypted text: 50zPJlUFIYY0o
Salt value #0 = 5
Salt value #1 = 0
Full Salt: 50?Z?V?
Password: aA

Password: A&A

Password: A&NV

Password: A&NXM

Password: 


Password: A&DwSOD

Password: A&BQVANT

我猜测salt问题正在影响crypt（）函数。

源代码：

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

/*
This program take an encrypted input
before encrypting a host of strings
and comparing those encryptions to
the original input. All files read
from are to be kept in the same
folder.
*/

int main(int argc, char *argv[])
{

    //Get and print text to be encyphered
    printf("\nTest\n");
    char enc1[50];
    char salt[2];
    char decyphered[50];
    char filename[8][15] = {"two.txt","three.txt",         "four.txt","five.txt","six.txt","seven.txt","eight.txt"};

    char wordtest[10];
    printf("\nPrint encrypted text: ");
    scanf("%s", enc1);
    printf("Encrypted text: %s\n", enc1);

    //Fill salt
    for (int i = 0; i < 2; i++)
    {
        salt[i] = enc1[i];
        printf("Salt value #%i = %c\n", i, salt[i]);
    }

    printf("Full Salt: %s", salt);

    //Run all possibilites and check result
    FILE *fp;

    for (int k = 0; k < 8; k++)
    {
        fp = fopen(filename[k],"r");  // opens files in read mode

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

        do
        {
            fgets(wordtest, k + 3, (FILE*)fp);
            *decyphered = crypt(wordtest, salt);
            if (memcmp(enc1, decyphered, (k + 2)))
            {
                printf("\nPassword: %s\n", wordtest);
            }
        }
        while(!memcmp(enc1, decyphered, (k + 2)) && wordtest != NULL);


    }

    return 0;
}

非常感谢任何帮助！

Answer 1

盐问题的最短解决方案是：

printf("Full Salt: %c%c", salt[0],salt[1]);

或者您可以定义salt[3]并设置salt[2] = '\0'然后使用printf打印%s

关于wordtest != NULL warning，当您将wordtest分配为char[10]时，您已经在堆栈中为该变量分配空间，因此将其与null进行比较是不合理的，但可能您想测试是否wordtest的内容为空或不可以使用：

strcmp(wordtest, "");

C语言中的基本蛮力计划

1 个答案: