export interface TotpOptions {
    step?: number;
    digits?: number;
    window?: number;
}
export declare class TotpService {
    private readonly step;
    private readonly digits;
    private readonly window;
    constructor(options?: TotpOptions);
    generateSecret(byteLength?: number): string;
    generateOTP(secret: string, timestamp?: number): string;
    verifyOTP(secret: string, code: string, timestamp?: number): boolean;
    generateQRUri(secret: string, issuer: string, account: string): string;
    generateBackupCodes(count?: number): string[];
}