/**
 * When checking the values of cryptographic hashes are equal, default
 * comparisons can be susceptible to timing based attacks, where attacker is
 * able to find out information about the host system by repeatedly checking
 * response times to equality comparisons of values.
 *
 * It is likely some form of timing safe equality will make its way to the
 * WebCrypto standard (see:
 * {@link https://github.com/w3c/webcrypto/issues/270 | w3c/webcrypto#270}), but until
 * that time, `timingSafeEqual()` is provided:
 *
 * ```ts
 * import { timingSafeEqual } from "https://deno.land/std@$STD_VERSION/crypto/timing_safe_equal.ts";
 * import { assert } from "https://deno.land/std@$STD_VERSION/assert/assert.ts";
 *
 * const a = await crypto.subtle.digest(
 *   "SHA-384",
 *   new TextEncoder().encode("hello world"),
 * );
 * const b = await crypto.subtle.digest(
 *   "SHA-384",
 *   new TextEncoder().encode("hello world"),
 * );
 *
 * assert(timingSafeEqual(a, b));
 * ```
 */
export declare function timingSafeEqual(a: ArrayBufferView | ArrayBufferLike | DataView, b: ArrayBufferView | ArrayBufferLike | DataView): boolean;