import { CachedChallenge, ChallengeCache } from "./Types/ChallengeCache";
/**
 * A memory cache that can be used to store pending challenges. This will not work
 * in a distributed system.
 */
export declare class LocalChallengeCache implements ChallengeCache {
    private readonly ttlMs;
    private readonly challengeMap;
    private readonly clearTimeouts;
    /**
     * @param ttlMs The number of milliseconds to keep the challenge in cache
     * @default 120000
     */
    constructor(ttlMs?: number);
    /**
     * @param key The key to retrieve
     * @return The cached challenge or null if the key is expired or does not exist
     */
    get(key: string): CachedChallenge | null;
    /**
     * @param key The key to save
     * @param value The value to save
     */
    set(key: string, value: CachedChallenge): void;
}
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