Web/API/Window/crypto

The read-only Window.crypto property returns the Crypto object associated to the global object. This object allows web pages access to certain cryptographic related services. Although the property itself is read-only, all of its methods (and the methods of its child object, SubtleCrypto) are not read-only, and therefore vulnerable to attack by polyfill.

Although window.crypto is available on all windows, the returned Crypto object only has one usable feature in insecure contexts: the getRandomValues() method. In general, you should use this API only in secure contexts.

Syntax

var cryptoObj = window.crypto || window.msCrypto; // for IE 11

Value

An instance of the Crypto interface, providing access to general-purpose cryptography and a strong random-number generator.

Example

This example uses the Window.crypto property to access the getRandomValues() method.

JavaScript

genRandomNumbers = function getRandomNumbers() {
  var array = new Uint32Array(10);
  window.crypto.getRandomValues(array);
 
  var randText = document.getElementById("myRandText");
  randText.innerHTML = "The random numbers are: "
  for (var i = 0; i < array.length; i++) {
    randText.innerHTML += array[i] + " ";
  }
}

HTML

<p id="myRandText">The random numbers are: </p>
<button type="button" onClick='genRandomNumbers()'>Generate 10 random numbers</button>

Result

Specifications

Specification	Status	Comment
Web Cryptography APIThe definition of 'Window.crypto' in that specification.	Recommendation	Initial definition

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`crypto`	Chrome Full support 37	Edge Full support 12	Firefox Full support 34	IE Full support 11 Prefixed' Full support 11 Prefixed' Prefixed' Implemented with the vendor prefix: ms	Opera Full support 24	Safari Full support 6.1	WebView Android Full support 37	Chrome Android Full support 37	Firefox Android Full support 34	Opera Android Full support 24	Safari iOS Full support 6.1	Samsung Internet Android Full support 3.0

Legend

Full support: Full support
Requires a vendor prefix or different name for use.': Requires a vendor prefix or different name for use.