/**
 * SMTP TLS Handler
 * Responsible for handling TLS-related SMTP functionality
 */
import * as plugins from '../../../plugins.js';
import type { ITlsHandler, ISmtpServer, ISmtpSession } from './interfaces.js';
/**
 * Handles TLS functionality for SMTP server
 */
export declare class TlsHandler implements ITlsHandler {
    /**
     * Reference to the SMTP server instance
     */
    private smtpServer;
    /**
     * Certificate data
     */
    private certificates;
    /**
     * TLS options
     */
    private options;
    /**
     * Creates a new TLS handler
     * @param smtpServer - SMTP server instance
     */
    constructor(smtpServer: ISmtpServer);
    /**
     * Handle STARTTLS command
     * @param socket - Client socket
     */
    handleStartTls(socket: plugins.net.Socket, session: ISmtpSession): Promise<plugins.tls.TLSSocket | null>;
    /**
     * Upgrade a connection to TLS
     * @param socket - Client socket
     */
    startTLS(socket: plugins.net.Socket): Promise<plugins.tls.TLSSocket>;
    /**
     * Create a secure server
     * @returns TLS server instance or undefined if TLS is not enabled
     */
    createSecureServer(): plugins.tls.Server | undefined;
    /**
     * Check if TLS is enabled
     * @returns Whether TLS is enabled
     */
    isTlsEnabled(): boolean;
    /**
     * Send a response to the client
     * @param socket - Client socket
     * @param response - Response message
     */
    private sendResponse;
    /**
     * Check if TLS is available (interface requirement)
     */
    isTlsAvailable(): boolean;
    /**
     * Get TLS options (interface requirement)
     */
    getTlsOptions(): plugins.tls.TlsOptions;
    /**
     * Clean up resources
     */
    destroy(): void;
}