In C language Write a program that will crack a Caesar cyphe

In C language!!!

Write a program that will crack a Caesar cypher using a brute-force approach (with some human help). You know that it is a simple Caesar cypher, but you do not know the key. So your program will need to try every key value. Starting with a key value of 1, increment each letter in the input string by this 1 (A\'s become B\'s, B\'s become C\'s, and so on) and print the resulting string. Then repeat 25 times, generating every possible output string. Then find a convenient human with a highlighter pen who can read the output and determine the key. Be carefull of rollover past the character \'z\'. If this happens you will need to subtract back to the start of the alphabet.

I suggest you use a small input string untill you get it working correctly.

For example: char input[] = \"epfexvsww\"; // albatross, key = 22

char input[] = \"jzfnlyetxlrtypdzxlyjxzyvpjdtyespoltwjxltwlwwzqespxnzxtyrlyzyjxzfdwjdzespjwplgpyzecltwtypgpceszfrseto slgplyloxtcpcqczxzgpcdpldmfedzxpzyptddpyotyrxpdeletzylcjqtwwpohtesnstxalykppddzxpnstxadtydhtxdfteddzx pnstxadlcpdhtyrtyrqczxlgtypdzxpnstxadtyulnvmzzeddzxpnstxadeslehtdsespjnzfwompxtypdelcdvjlyosfensnstxa dlnstxahszddteetyrzyespnlylaltczqofensnstxadhszdpyoesptcwzgpqczxlxdepcolxlyzespcazdenlcohtesnstxalykp pdlyopgpcjzyptdloocpddpoezxp\";

Sample Output (epfexvsww = albatross, key = 22):

0 epfexvsww

1 fqgfywtxx

2 grhgzxuyy

3 hsihayvzz

4 itjibzwaa

5 jukjcaxbb

6 kvlkdbycc

7 lwmleczdd

8 mxnmfdaee

9 nyongebff

10 ozpohfcgg

11 paqpigdhh

12 qbrqjheii

13 rcsrkifjj

14 sdtsljgkk

15 teutmkhll

16 ufvunlimm

17 vgwvomjnn

18 whxwpnkoo

19 xiyxqolpp

20 yjzyrpmqq

21 zkazsqnrr

22 albatross

23 bmcbusptt

24 cndcvtquu

25 doedwurvv

Press any key to continue . . .

Solution

Algorithm for caesar cipher:-

If C_i is the character value in the text then, Encrypted text = char(C_i + Key)%26.

WORKING C PROGRAM :-

#include<stdio.h>

void print(char s[], int key) {
       char temp;
       printf(\"%d :\", key);
       for(int i=0; s[i]!=0; i++) {
           int c_val = (s[i]-\'a\');
           temp = (char)((c_val+key)%26 + \'a\');
           printf(\"%c\", temp);
       }
       printf(\"\ \");
}

void crackCaesar(char s[])
{
   for(int i=0; i<26; i++)
   {
       print(s, i);
   }
}

int main()
{
   char inp[500]; //I am asuming that maximum length of input is 500. You can change it.
   printf(\"Enter the string :\ \");
   scanf(\"%s\", inp);
   crackCaesar(inp);
   return 0;
}