import { Observable } from 'rxjs';
import { HOTPGenerateOptions, HOTPVerifyOptions, OTPVerifyResult } from '../schemas/interfaces';
export declare class HOTP {
    static generate: (key: string, options?: HOTPGenerateOptions) => Observable<string>;
    static verify: (token: string, key: string, options?: HOTPVerifyOptions) => Observable<OTPVerifyResult | {}>;
}