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CeaserCipher.java
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56 lines (56 loc) · 1.38 KB
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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
public class CeaserCipher {
static Scanner sc=new Scanner(System.in);
static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
public static void main(String[] args) throws IOException {
// TODO code application logic here
System.out.print("Enter any String: ");
String str = br.readLine();
System.out.print("\nEnter the Key: ");
int key = sc.nextInt();
String encrypted = encrypt(str, key);
System.out.println("\nEncrypted String is: " +encrypted);
String decrypted = decrypt(encrypted, key);
System.out.println("\nDecrypted String is: "
+decrypted); System.out.println("\n");
}
public static String encrypt(String str, int key)
{ String encrypted = "";
for(int i = 0; i < str.length(); i++) {
int c = str.charAt(i);
if (Character.isUpperCase(c)) {
c = c + (key % 26);
if (c > 'Z')
c = c - 26;
}
else if (Character.isLowerCase(c)) {
c = c + (key % 26);
if (c > 'z')
c = c - 26;
}
encrypted += (char) c;
}
return encrypted;
}
public static String decrypt(String str, int key)
{ String decrypted = "";
for(int i = 0; i < str.length(); i++) {
int c = str.charAt(i);
if (Character.isUpperCase(c)) {
c = c - (key % 26);
if (c < 'A')
c = c + 26;
}
else if (Character.isLowerCase(c)) {
c = c - (key % 26);
if (c < 'a')
c = c + 26;
}
decrypted += (char) c;
}
return decrypted;
}
}