/// <reference types="node" />
export declare const validateSecret: (secret: Buffer) => void;
export declare const validateDigits: (digits: number) => void;
export declare const validateCounter: (counter: number) => void;
export declare const validateInterval: (interval: number) => void;
export declare const validateTime: (time: number) => void;
export declare const validateHmacAlgorithm: (hmacAlgorithm: string) => void;