ShiftChiper.cpp

/*
Nama        : Mohammad Faris Arie Prasetyo
NPM         : 140810190056
Kelas       : Kriptografi A
Deskripsi   : Enkripsi Deskripsi Shift Chiper
*/

#include <iostream>
#include <limits.h>
#include <stdio.h>
#include <string.h>

using namespace std;

void Enkripsi(char text[], int key){
	char plaintext;
	for (int i = 0; text[i] != '\0'; ++i){
		plaintext = text[i];

		if (plaintext >= 'a' && plaintext <= 'z'){
			plaintext = plaintext + key;
			if (plaintext > 'z') {
				plaintext = plaintext - 'z' + 'a' - 1;
			}
			text[i] = plaintext;
		}
		else if (plaintext >= 'A' && plaintext <= 'Z'){
			plaintext = plaintext + key;
			if (plaintext > 'Z') {
					plaintext = plaintext - 'Z' + 'A' - 1;
			}
			text[i] = plaintext;
		}
	}
	printf("\nHasil Enkripsi  : %s", text);
}

void Deskripsi(char text[], int key){
	char ciphertext;
		for (int i = 0; text[i] != '\0'; ++i){
			ciphertext = text[i];

			if (ciphertext >= 'a' && ciphertext <= 'z'){
				ciphertext = ciphertext - key;
				if (ciphertext < 'a') {
					ciphertext = ciphertext + 'z' - 'a' + 1;
				}
				text[i] = ciphertext;
			}
			else if (ciphertext >= 'A' && ciphertext <= 'Z'){
				ciphertext = ciphertext - key;
				if (ciphertext < 'A') {
					ciphertext = ciphertext + 'Z' - 'A' + 1;
				}
				text[i] = ciphertext;
			}
		}
		printf("\nHasil Deskripsi : %s", text);
}

int main() {
	int key, length;
	char text[100];
	
	cout << "Masukkan Text : ";
	cin.getline(text,100);

	cout << "Masukkan Key  : ";
	cin >> key;

	length = strlen(text);

	Enkripsi(text, key);
	
	Deskripsi(text, key);
}