import { Buffer } from 'node:buffer';
export declare const base64url: (buffer: Buffer) => string;
export declare const base64nopad: (buffer: Buffer) => string;
export declare const toHexString: (input: string) => string;
/** The query string of a request, every key and value URL-encoded: a keyword
 *  or an author name with a space or an accent would otherwise make an invalid
 *  URL, whose signature Audible refuses with a 403. */
export declare const toQueryString: (query: Record<string, string>) => string;
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