import crypto from "crypto";
type Fetch = typeof fetch;
export interface KeyCache<KT extends string = string, VT extends crypto.KeyObject = crypto.KeyObject> {
    get(k: KT): Promise<VT | null | undefined> | VT | null | undefined;
    set(k: KT, v: VT): void;
}
export type KeyFetcher = (version: string) => Promise<crypto.KeyObject>;
export interface KeyFetcherOptions {
    baseURL?: string;
    cache?: KeyCache;
    fetch?: Fetch;
}
export declare const keyFetcher: (options?: KeyFetcherOptions) => KeyFetcher;
export {};