@Override
    public void initialize(int keysize, SecureRandom random) {
        if (keysize != 255) {
            throw new IllegalArgumentException("Only X25519 supported");
        }
    }
An implementation of {@link KeyPairGenerator} for XDH keys which uses BoringSSL to perform all
the operations. This only supports X25519 keys.
common/src/main/java/org/conscrypt/OpenSSLXDHKeyPairGenerator.java