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simple_crypto.c
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simple_crypto.c
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#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <malloc.h>
#include "simple_crypto.h"
char *one_time_pad_encryption(char *plaintext, const char *secret_key) {
static char *crypto;
crypto = malloc(strlen(plaintext) * sizeof(char));
int i;
for (i = 0; i < strlen(plaintext); i++) {
crypto[i] = plaintext[i] ^ secret_key[i];
}
crypto[i] = '\0';
printf("[OTP] encrypted: ");
int j;
for (j = 0; j < strlen(plaintext); j++) {
char crypto_temp;
crypto_temp = crypto[j];
if (isprint(crypto_temp) == 0) {
printf("$");
} else {
printf("%c", crypto_temp);
}
}
printf("\n");
return crypto;
}
char *one_time_pad_decryption(char *crypto, const char *secret_key, int size_of_plaintext) {
int i;
static char *decrypted_message;
decrypted_message = malloc(size_of_plaintext * sizeof(char));
for (i = 0; i < size_of_plaintext; i++) {
decrypted_message[i] = crypto[i] ^ secret_key[i];
}
decrypted_message[i] = '\0';
// printf("[OTP] decrypted: %s", decrypted_message);
scanf("%*c");
return decrypted_message;
}
char *ceasar_cipher_encryption(char *plainText, int key) {
int i;
static char *cipher;
cipher = malloc(strlen(plainText) * sizeof(char));
//Encryption
// printf("[Ceasars] encrypted: ");
plainText[strlen(plainText)] = '\0';
for (i = 0; i < strlen(plainText); i++) {
// printf("%d\n",(int)plainText[i] );
//if the character is lowercase, where range is [97 -122]
if (isalpha(plainText[i]) != 0) {
if (islower(plainText[i]) != 0) {
int lower_alpha_pos;
// printf("Inside Lower\n");
// printf("\n2 %d\n",( (int)plainText[i]- 48 ) );
lower_alpha_pos = (int) plainText[i] - 61;
cipher[i] = (char) AlphabetWithDigits[(lower_alpha_pos + key) % 62][0];
} else if (isupper(plainText[i]) != 0) {
int upper_alpha_pos;
// printf("ALpha inside %c\n",AlphabetWithDigits[10][0] );
upper_alpha_pos = (int) plainText[i] - 55;
cipher[i] = (char) AlphabetWithDigits[(upper_alpha_pos + key) % 62][0];
}
// printf("\n1 %d\n",( (int)plainText[i] ));
} else if (isdigit(plainText[i]) != 0) {
int digit_pos;
// printf("\n2 %d\n",( (int)plainText[i]- 48 ) );
digit_pos = (int) plainText[i] - 48;
// printf("HAH %d\n",( digit_pos + key) % 62 );
// printf("ALpha inside %c\n",AlphabetWithDigits[7][0] );
cipher[i] = (char) AlphabetWithDigits[(digit_pos + key) % 62][0];
}
// printf("%c", cipher[i]);
}
return cipher;
}
char *ceasar_cipher_decryption(char *crypto, int key) {
//Decryption
static char *cipher;
cipher = malloc(strlen(crypto) * sizeof(char));
// printf("[Ceasars] decrypted: ");
// printf("3EW %s\n",crypto );
for (int i = 0; i < strlen(crypto); i++) {
// printf("Crypto char: %c : %d : Cipher: ",crypto[i], (int)crypto[i] );
if (islower(crypto[i]) != 0) {
int lower_alpha_pos;
// printf("Inside Lower\n");
// printf("\n2 %d\n",( (int)plainText[i]- 48 ) );
lower_alpha_pos = (int) crypto[i] - 61;
// printf("%d\n",(int)crypto[i] );
// printf("%d\n",lower_alpha_pos );
cipher[i] = (char) AlphabetWithDigits[(lower_alpha_pos - key) % 62][0];
// printf("XAXAAXAAXAXXA %c\n",cipher[i] );
} else if (isupper(crypto[i]) != 0) {
int upper_alpha_pos;
// printf("ALpha inside %c\n",AlphabetWithDigits[10][0] );
upper_alpha_pos = (int) crypto[i] - 55;
cipher[i] = (char) AlphabetWithDigits[(upper_alpha_pos - key) % 62][0];
}
else if (isdigit(crypto[i]) != 0) {
int digit_pos;
// printf("2 : %d\n",( (int)crypto[i]- 48 ) );
digit_pos = (int) crypto[i] - 48;
// printf("HAH %d\n",( digit_pos + key) % 62 );
// printf("ALpha inside %c\n",AlphabetWithDigits[7][0] );
if( digit_pos == 0){
cipher[i] = (char) AlphabetWithDigits[(digit_pos - key) % 62 + 62][0] ;
}
else{
cipher[i] = (char) AlphabetWithDigits[(digit_pos - key) % 62][0] ;
}
}
// printf("%c", cipher[i]);
}
scanf("%*c");
return cipher;
}
void generateKey(char *str, char *key) {
int x = strlen(str);
int y = strlen(key);
int j = 0;
for (int i = 0; i < x; i++) {
if (i >= y) {
key[i] = key[j];
j++;
if (j == y) {
j = 0;
}
} else {
key[i] = key[i];
}
// printf("%c ",value[i] );
}
// printf("KEY: %s\n",key );
}
char * vigenere_cipher_encryption(char *plainText, char *key){
int i;
generateKey(plainText, key);
// printf("[Vigenere] encrypted: ");
static char *cipher;
cipher = malloc(strlen(plainText) * sizeof(char));
int cipherValue;
int len = strlen(key);
//Loop through the length of the plain text string
for (i = 0; i < strlen(plainText); i++) {
//if the character is lowercase, where range is [97 -122]
cipherValue = ((int) plainText[i] - 65 + (int) toupper(key[i % len]) - 65) % 26 + 65;
cipher[i] = (char) cipherValue;
// printf("%c",cipher[i]);
}
cipher[i] = '\0';
return cipher;
}
char * vigenere_cipher_decryption(char *crypto, char *key){
int len = strlen(key);
int i;
// printf("[Vigenere] decrypted: ");
static char *cipher;
cipher = malloc(strlen(crypto) * sizeof(char));
int decipherValue;
//Loop through the length of the plain text string
for (i = 0; i < strlen(crypto); i++) {
//if the character is lowercase, where range is [97 -122]
if (islower(crypto[i])) {
decipherValue = (((int) crypto[i] - 97) - ((int) tolower(key[i % len]) - 97) + 26) % 26 + 97;
cipher[i] = (char) decipherValue;
} else // Else it's upper case, where letter range is [65 - 90]
{
decipherValue = (((int) crypto[i] - 65) - ((int) toupper(key[i % len]) - 65) + 26) % 26 + 65;
cipher[i] = (char) decipherValue;
}
//Print the ciphered character if it is alphanumeric (a letter)
if (isalpha(crypto[i])) {
cipher[i] = cipher[i];
// printf("%c", cipher[i]);
} else //if the character is not a letter then print the character (e.g. space)
{
cipher[i] = crypto[i];
// printf("%c", crypto[i]);
}
}
return cipher;
}