Notes

package siber;

import java.util.Scanner;

public class Siber
{
/* encrypt and decrypt a text using a simple algorithm of metinting the letters */

static char[] chars = {
'a', 'b', 'c', 'ç', 'd', 'e', 'f', 'g', 'ğ', 'h',
'ı', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'ö', 'p',
'q', 'r', 's', 'ş', 't', 'u', 'ü', 'v', 'w', 'x',
'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7',
'8', '9', 'A', 'B', 'C', 'Ç', 'D', 'E', 'F', 'G',
'Ğ', 'H', 'I', 'İ', 'J', 'K', 'L', 'M', 'N', 'O',
'Ö', 'P', 'Q', 'R', 'S', 'Ş', 'T', 'U', 'Ü', 'V',
'W', 'X', 'Y', 'Z', '!', '@', '#', '$', '%', '^',
'&', '(', ')', '+', '-', '*', '/', '[', ']', '{',
'}', '=', '<', '>', '?', '_', '"', '.', ',', ' '

};

public static void main(String[] args)
{
/*String text = "abcç123";
int metin = 2;

String enc = encrypt(text, metin);
System.out.println("Encrypted text: " + enc);

String dec = decrypt(enc, metin);
System.out.println("Decrypted text: " + dec);
*/
int secim;

Scanner sc = new Scanner(System.in);


System.out.println("Metni Giriniz: ");
String text = new String();
text = sc.next();

System.out.println("Şifrele için 1 çöz için 2 girin");
secim = sc.nextInt();


switch (secim) {


case 1 :
int metin;
System.out.println("Anahtar Giriniz (Sayı): ");
metin = sc.nextInt();
String enc = encrypt(text, metin);
System.out.println(enc);
break;


case 2:
System.out.println("Anahtar Giriniz (Sayı): ");
int metin2 = sc.nextInt();
String dec = decrypt(text, metin2);
System.out.println(dec);
sc.close();
break;
}
}

// Caesar cipher
static String encrypt(String text, int metin)
{
char[] plain = text.toCharArray();

for (int i = 0; i < plain.length; i++) {
for (int j = 0; j < chars.length; j++) {
if (j <= chars.length - metin) {
if (plain[i] == chars[j]) {
plain[i] = chars[j + metin];
break;
}
}
else if (plain[i] == chars[j]) {
plain[i] = chars[j - (chars.length - metin + 1)];
}
}
}
return String.valueOf(plain);
}

static String decrypt(String cip, int metin2)
{
char[] cipher = cip.toCharArray();
for (int i = 0; i < cipher.length; i++) {
for (int j = 0; j < chars.length; j++) {
if (j >= metin2 && cipher[i] == chars[j]) {
cipher[i] = chars[j - metin2];
break;
}
if (cipher[i] == chars[j] && j < metin2) {
cipher[i] = chars[(chars.length - metin2 +1) + j];
break;
}
}
}
return String.valueOf(cipher);
}
}