/* Modify the Cryptogram program to use a different type of key
system or algorithm. Consider using a user-defined key or a
different character set.
system or algorithm. Consider using a user-defined key or a
different character set.*/

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
//function prototypes
void encrypt(char [], int);
void decrypt(char [], int);
main()
{
char myString[21] = {0};
int iSelection = 0;
int iRand;
srand (time(NULL));
iRand = (rand() % 4) + 1; // random #, 1-4
while ( iSelection != 4 ) {
printf("\n\n1\tEncrypt Clear Text\n");
printf("2\tDecrypt Cipher Text\n");
printf("3\tGenerate New Key\n");
printf("4\tQuit\n");
printf("\nSelect a Cryptography Option: ");
scanf("%d", &iSelection);
switch (iSelection) {
case 1:
printf("\nEnter one word as clear text to encrypt: ");
scanf("%s", myString);
encrypt(myString, iRand);
break;
case 2:
printf("\nEnter cipher text to decrypt: ");
scanf("%s", myString);
decrypt(myString, iRand);
break;
case 3:
iRand = (rand() % 4) + 1; // random #, 1-4
printf("\nNew Key Generated\n");
break;
} //end switch
} //end loop
} //end main
void encrypt(char sMessage[], int random)
{
int x = 0;
//encrypt the message by shifting each characters ASCII value
while ( sMessage[x] ) {
sMessage[x] += random;
x++;
} //end loop
x = 0;
printf("\nEncrypted Message is: ");
//print the encrypted message
while ( sMessage[x] ) {
printf("%c", sMessage[x]);
x++;
} //end loop
} //end encrypt function
void decrypt(char sMessage[], int random)
{
int x = 0;
x = 0;
//decrypt the message by shifting each characters ASCII value
while ( sMessage[x] ) {
sMessage[x] = sMessage[x] - random;
x++;
} //end loop
x = 0;
printf("\nDecrypted Message is: ");
//print the decrypted message
while ( sMessage[x] ) {
printf("%c", sMessage[x]);
x++;
} //end loop
} //end decrypt function

void gen_key(char *key, char *plaintext)
{
 int len = strlen(plaintext);
 //depending if you allocated memory or not for key you might need to call malloc to allocate memory. rmeember to free afterwards.
 for(int i = 0; i < len; i++)
  {
       *key = rand()%26+'a';
   }
}

void encrypt(char *key, char *plaintext)
{
  int len = strlen(plaintext);
 
   for(int i = 0; i < len; i++)
   {
       //implement xor where you XOR i of both arrays together storing them in plaintext
    }
}