import * as React from "react";
declare const lengthRange: readonly [4, 5, 6, 7, 8];
declare type TLength = typeof lengthRange[number];
interface IUserOpt {
    type: "mixed" | "numeric" | "alpha";
    length?: TLength;
    sensitive?: boolean;
    width?: number;
    height?: number;
    fontColor?: string;
    background?: string;
}
interface ReturnValue {
    gen: () => void;
    validate: (string: string) => boolean;
}
export default function useOfflineCaptcha(ref: React.RefObject<HTMLElement>, UserOpt: IUserOpt): ReturnValue;
export {};