export declare const getChallengeCacheKey: (did: string, challenge: string) => string;
export declare const VALID = "valid";
export declare const isChallengeValidForDid: (did: string, challenge: string) => Promise<typeof VALID | null | undefined>;
export declare const setValidChallengeForDid: (did: string, challenge: string) => Promise<"OK" | undefined>;
export declare const setValidChallengesForDid: (did: string, challenges: string[]) => Promise<"OK" | undefined>;
export declare const invalidateChallengeForDid: (did: string, challenge: string) => Promise<number | undefined>;
