import java.io.IOException;

import java.nio.charset.StandardCharsets;

import java.util.Base64;

public class CookieHasher {

/**

* Hashes a session cookie value with optional salt and encoding.

* @param cookieValue The session cookie value to hash.

* @param salt Optional salt value to use for hashing.

* @param encode Optional boolean indicating whether to encode the result in Base64.

* @return The hashed value as a string.

* @throws IllegalArgumentException if cookieValue is null.

*/

public static String hashCookie(String cookieValue, String salt, boolean encode) {

if (cookieValue == null) {

throw new IllegalArgumentException("Cookie value cannot be null.");

}

String data = cookieValue + (salt != null ? salt : ""); //Concatenate cookie and salt

byte[] bytes = data.getBytes(StandardCharsets.UTF_8); // Convert to bytes

// Simple hash implementation (can be replaced with a more robust algorithm)

int hash = 0;

for (byte b : bytes) {

hash = (hash * 31 + b) % 1000000007; // A prime number for modulo

}

String hashString = String.valueOf(hash);

if (encode) {

byte[] encodedBytes = Base64.getEncoder().encode(hashString.getBytes(StandardCharsets.UTF_8));

return new String(encodedBytes, StandardCharsets.UTF_8);

} else {

return hashString;

}

}

public static void main(String[] args) {

//Example Usage

String cookie = "abcdef123456";

String salt = "mySecretSalt";

String hashedValue = hashCookie(cookie, null, false); //No salt, no encode

System.out.println("Hashed value: " + hashedValue);

String hashedAndEncoded = hashCookie(cookie, salt, true); //With salt, encode in base64

System.out.println("Hashed and encoded value: " + hashedAndEncoded);

try {

hashCookie(null, null, false);

} catch (IllegalArgumentException e) {

System.out.println("Exception caught: " + e.getMessage());

}

}

}