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@sdwvit sdwvit/crack.c
Created May 15, 2019

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#include <cs50.h>
#include <stdio.h>
#include <crypt.h>
#include <string.h>
int A_charcode = 65;
int a_charcode = 97;
int abc_size = 25;
string hash;
bool success = false;
int iterator = 0;
/**
* replaces letter with the next one from alphabet
* incrementLetter('a') => 'b'
*/
char incrementLetter(char letter)
{
return (char)((int)letter + 1);
}
#define ARRAY_CONCAT(TYPE, A, An, B, Bn) \
(TYPE *)array_concat((const void *)(A), (An), (const void *)(B), (Bn), sizeof(TYPE));
/**
* concats 2 arrays
* ARRAY_CONCAT("abc", "def") => "abcdef"
*/
void *array_concat(const void *a, size_t an,
const void *b, size_t bn, size_t s)
{
char *p = malloc(s * (an + bn));
memcpy(p, a, an * s);
memcpy(p + an * s, b, bn * s);
return p;
}
/**
* slices array from start to end
* slice("abc", 0, 2) => "ab"
*/
void *slice(string s1, int start, int end)
{
char *t = malloc((end - start) * sizeof(char));
for (int j = 0; j < end - start; j++)
{
t[j] = s1[j + start];
}
return t;
}
/**
* gives next word based on incrementLetter
* getNextWord("abc") => "bbc"
*/
string getNextWord(string s1)
{
char first_letter = s1[0];
if (first_letter == ' ')
{
s1[0] = 'A';
}
else if (first_letter == 'Z')
{
s1[0] = 'a';
}
else if (first_letter < 'z')
{
s1[0] = incrementLetter(first_letter);
}
else if (first_letter == 'z')
{
string first_letter_str = slice(s1, 0, 1);
first_letter_str[0] = 'A';
string next_word_substr = slice(s1, 1, strlen(s1));
if (!next_word_substr[0])
{
next_word_substr[0] = 'A';
}
else
{
next_word_substr = getNextWord(next_word_substr);
}
return ARRAY_CONCAT(char, first_letter_str, 1, next_word_substr, strlen(next_word_substr));
}
return s1;
}
/**
* compares 2 strings
* equals("abc", "abc") => true
* equals("abc", "bcd") => false
*/
bool equals(string s1, string s2)
{
if (strlen(s1) != strlen(s2))
{
return false;
}
for (int i = 0; i < strlen(s1); i++)
{
if (s1[i] != s2[i])
{
return false;
}
}
return true;
}
int main(int argc, string argv[])
{
if (argc != 2)
{
printf("Usage: ./crack hash\n");
return 1;
}
hash = argv[1];
char *word = malloc(6 * sizeof(char));
string salt = slice(hash, 0, 2);
word[0] = ' '; // special char to start populating word
while (!success)
{
word = getNextWord(word);
success = equals(crypt(word, salt), hash);
}
printf("word: %s\n", word);
}
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