I am a java programmer. I am intended to generate a set of keypair with “X25519” instance.

I am using JDK 8, hence I am implementing BouncyCastle library to achieve this.

The BC version I am using is bcprov-jdk18on-1.78.1.jar which I get it from the official website.

I have tried to use the code below to get the result.

import org.bouncycastle.jce.ECNamedCurveTable;
import org.bouncycastle.jce.spec.ECNamedCurveParameterSpec;
import org.bouncycastle.jce.interfaces.ECPrivateKey;
import org.bouncycastle.jce.interfaces.ECPublicKey;
import java.security.*;
import java.security.spec.InvalidKeySpecException;
import java.security.spec.KeySpec;
import java.util.Base64;

public class X25519KeyGenerator {

    public static void main(String[] args) {
        try {
            // Generate X25519 key pair using Bouncy Castle
            KeyPair keyPair = generateX25519KeyPair();

            // Get private and public keys
            PrivateKey privateKey = keyPair.getPrivate();
            PublicKey publicKey = keyPair.getPublic();

            // Encode keys in Base64 format
            String privateKeyBase64 = encodeKeyToBase64(privateKey);
            String publicKeyBase64 = encodeKeyToBase64(publicKey);

            System.out.println("Private Key (Base64): " + privateKeyBase64);
            System.out.println("Public Key (Base64): " + publicKeyBase64);
            System.out.println("Private Key Length: " + privateKeyBase64.length());
            System.out.println("Public Key Length: " + publicKeyBase64.length());
        } catch (NoSuchAlgorithmException | NoSuchProviderException | InvalidKeySpecException e) {
            e.printStackTrace();
        }
    }

    // Generate X25519 key pair using Bouncy Castle
    public static KeyPair generateX25519KeyPair() throws NoSuchAlgorithmException, NoSuchProviderException, InvalidKeySpecException {
        Security.addProvider(new org.bouncycastle.jce.provider.BouncyCastleProvider());
        KeyPairGenerator keyGen = KeyPairGenerator.getInstance("X25519", "BC");
        return keyGen.generateKeyPair();
    }

    // Encode key to Base64 format
    public static String encodeKeyToBase64(Key key) {
        return Base64.getEncoder().encodeToString(key.getEncoded());
    }
}

The result I got from the code is as below.

Private Key (Base64): MFECAQEwBQYDK2VuBCIEIPAZWyLiw7qF9UaND6hFp+cJPvcl4TiDY+ab9s9vBrlkgSEAWvvMm0LCB0qzTa68jQ0gvB48ZqsOR6LRmFZdw0aT4kM= Public Key (Base64): MCowBQYDK2VuAyEAWvvMm0LCB0qzTa68jQ0gvB48ZqsOR6LRmFZdw0aT4kM= Private Key Length: 112 Public Key Length: 60

I was expecting it to be 44 in length. May I know what is the possible issue with this?