/**
 * Converts a hexadecimal string to an ArrayBuffer.
 * @param {string} str Hexadecimal string.
 * @returns {ArrayBuffer} ArrayBuffer.
 */
export function hexToBuf(str: string): ArrayBuffer;
/**
 * Converts an ArrayBuffer to a hexadecimal string.
 * @param {ArrayBuffer} buf ArrayBuffer.
 * @returns {string} Hexadecimal string.
 */
export function hexFromBuf(buf: ArrayBuffer): string;