monoalphabetic cipher code in c
//Monoalphabetic cipher
#include <stdio.h>
#include <string.h>
#include <malloc.h>
char *keycipher(char t[], int tl, char k[], int kl, int a)
{
char *ct = malloc(tl);
char newaz[26] = {0};
int orgaz[26] = {0};
int c = 0;
for (int i = 0; i < kl; i++)
{
int kc = k[i] - 97;
if (orgaz[kc] == 0)
{
orgaz[kc] = c;
newaz[c++] = kc + 97;
}
}
for (int i = 0; i < 26; i++)
{
if (orgaz[i] == 0)
{
orgaz[i] = c;
newaz[c++] = i + 97;
}
}
c = 0;
for (int i = 0; i < tl; i++)
{
if (a == 0)
{
ct[c++] = (t[i] == 32) ? 32 : newaz[t[i] - 97];
}
else
{
ct[c++] = (t[i] == 32) ? 32 : orgaz[t[i] - 97] + 97;
}
}
ct[tl] = '\0';
return ct;
}
int main()
{
printf("\nMonoalphabetic Cipher\n");
int ch = 0;
while (ch != 3)
{
printf("\n\n1.Encrypt\n2.Decrypt\n3.Exit");
printf("\nSelect Option: ");
scanf("%d", &ch);
switch (ch)
{
case 1:
{
char pt[50], key[50];
printf("\nEnter plain text: ");
scanf(" %[^\n]%*c", pt);
printf("\nEnter the keyword: ");
scanf(" %[^\n]%*c", key);
printf("\nCipher Text: %s", keycipher(pt, strlen(pt), key, strlen(key), 0));
break;
}
case 2:
{
char ct[50], key[50];
printf("\nEnter cipher text: ");
scanf(" %[^\n]%*c", ct);
printf("\nEnter the keyword: ");
scanf(" %[^\n]%*c", key);
printf("\nOriginal Text: %s", keycipher(ct, strlen(ct), key, strlen(key), 1));
break;
}
case 3:
return 0;
default:
printf("\nInvalid Choice!");
}
}
return 0;
}