/**
 * @param {string} [digits=6]
 * @param {string} [algorithm="SHA-1"]
 * @param {string} [period=30]
 * @param {string} [timestamp=Date.now()]
 */
export type TOTPOptions = {
    digits?: number;
    algorithm?: 'SHA-1' | 'SHA-224' | 'SHA-256' | 'SHA-384' | 'SHA-512' | 'SHA3-224' | 'SHA3-256' | 'SHA3-384' | 'SHA3-512';
    period?: number;
    timestamp?: number;
};
/**  generate TOTP tokens from a TOTP key */
export declare class TOTP {
    static generate(key: string, options?: TOTPOptions): {
        otp: string;
        expires: number;
    };
    private static hex2dec;
    private static dec2hex;
    private static base32tohex;
    private static leftpad;
}