/**
 * Encode a `Buffer` / `Uint8Array` as unpadded base64url.
 *
 * @param {Buffer | Uint8Array} bytes
 * @returns {string}
 */
export function encode(bytes: Buffer | Uint8Array): string;
/**
 * Decode an unpadded base64url string into a `Buffer`.
 * Rejects strings containing padding, whitespace, or non-alphabet chars.
 *
 * @param {string} text
 * @returns {Buffer}
 */
export function decode(text: string): Buffer;
/**
 * Assert that `text` is a well-formed unpadded base64url string and
 * (optionally) decodes to exactly `expectedBytes` bytes. Errors mention
 * the JWK member name to make validation output actionable.
 *
 * @param {string} text
 * @param {string} memberName which JWK member the value came from
 * @param {number} [expectedBytes]
 * @returns {Buffer}
 */
export function decodeMember(text: string, memberName: string, expectedBytes?: number): Buffer;