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package java.security.interfaces;

import java.security.PrivateKey;

import java.util.Optional;

/**

 * An interface for an elliptic curve private key as defined by

 * <a href="https://tools.ietf.org/html/rfc8032">RFC 8032: Edwards-Curve

 * Digital Signature Algorithm (EdDSA)</a>. These keys are distinct from the

 * keys represented by {@code ECPrivateKey}, and they are intended for use

 * with algorithms based on RFC 8032 such as the EdDSA {@code Signature}

 * algorithm.

 * <p>

 * An Edwards-Curve private key is a bit string. This interface only supports bit

 * string lengths that are a multiple of 8, and the key is represented using

 * a byte array.

 *

 * @since 15

 */

public interface EdECPrivateKey extends EdECKey, PrivateKey {

    /**

     * Get a copy of the byte array representing the private key. This method

     * may return an empty {@code Optional} if the implementation is not

     * willing to produce the private key value.

     *

     * @return an {@code Optional} containing the private key byte array.

     * If the key is not available, then an empty {@code Optional}.

     */

    Optional<byte[]> getBytes();

}