import ByteArray from '../internal/ByteArray.js';
import ServerSecretParams from '../ServerSecretParams.js';
/**
 * The key pair used to issue and verify group send endorsements.
 *
 * Group send endorsements use a different key pair depending on the endorsement's expiration (but
 * not the user ID being endorsed). The server may cache these keys to avoid the (small) cost of
 * deriving them from the root key in {@link ServerSecretParams}. The key object stores the
 * expiration so that it doesn't need to be provided again when issuing endorsements.
 *
 * @see {@link GroupSendEndorsementsResponse.issue}
 * @see {@link GroupSendFullToken#verify}
 */
export default class GroupSendDerivedKeyPair extends ByteArray {
    constructor(contents: Uint8Array<ArrayBuffer>);
    /**
     * Derives a new key for group send endorsements that expire at `expiration`.
     *
     * `expiration` must be day-aligned as a protection against fingerprinting by the issuing server.
     */
    static forExpiration(expiration: Date, params: ServerSecretParams): GroupSendDerivedKeyPair;
}