import { TwilioConfig } from './config/TwilioConfig';
import { generateSecret } from './utils/TokenUtils';
export declare class TwoFactorAuth {
    private client;
    private fromNumber;
    constructor(config: TwilioConfig);
    /**
     * Generates a new TOTP secret.
     * @returns The generated secret.
     */
    generateSecret(): ReturnType<typeof generateSecret>;
    /**
     * Generates a TOTP token based on a user's secret.
     * @param secret The user's TOTP secret.
     * @returns The generated token.
     */
    generateToken(secret: string): string;
    /**
     * Verifies a user-provided TOTP token against their secret.
     * @param token The TOTP token to verify.
     * @param secret The user's TOTP secret.
     * @returns True if the token is valid, otherwise false.
     */
    verifyToken(token: string, secret: string): boolean;
    /**
     * Sends an SMS message containing the TOTP token to a user's phone number.
     * @param phoneNumber The destination phone number, including country code.
     * @param message The message to send, typically containing the TOTP token.
     * @returns A promise resolved with the message sid if sending succeeds.
     */
    sendSmsOTP(phoneNumber: string, message: string): Promise<string>;
}