The SubtleCrypto.digest() method returns a Promise of a digest generated from the hash function and text given as parameters.

Note: Older insecure hash functions, like MD5, are not supported by this method. Even a supported method, SHA-1, is considered weak and should be avoided, at least in any new project.


var hash = crypto<code>.subtle.digest(algo, buffer)</code>;


  • algo is a DOMString defining the hash function to use. Supported values are: SHA-1, SHA-256, SHA-384, and SHA-512.
  • buffer is a ArrayBuffer or an ArrayBufferView containing the data to be hashed using the hashing algorithm.

Return value

  • hash is a Promise that returns the hash on success.


Here's an example that computes the sha256 of a string and display its hex digest.

function sha256(str) {
  // We transform the string into an arraybuffer.
  var buffer = new TextEncoder("utf-8").encode(str);
  return crypto.subtle.digest("SHA-256", buffer).then(function (hash) {
    return hex(hash);

function hex(buffer) {
  var hexCodes = [];
  var view = new DataView(buffer);
  for (var i = 0; i < view.byteLength; i += 4) {
    // Using getUint32 reduces the number of iterations needed (we process 4 bytes each time)
    var value = view.getUint32(i)
    // toString(16) will give the hex representation of the number without padding
    var stringValue = value.toString(16)
    // We use concatenation and slice for padding
    var padding = '00000000'
    var paddedValue = (padding + stringValue).slice(-padding.length)

  // Join all the hex strings into one
  return hexCodes.join("");

sha256("foobar").then(function(digest) {
}); // outputs "c3ab8ff13720e8ad9047dd39466b3c8974e592c2fa383d4a3960714caef0c4f2"


Specification Status Comment
Web Cryptography API
The definition of 'SubtleCrypto.digest()' in that specification.
Candidate Recommendation Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support (SHA-1 and SHA-2 algorithms) 37 34 (34) No support ? No support
Feature Android Chrome for Android Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support (SHA-1 and SHA-2 algorithms) (Yes) 37 34.0 (34) No support ? No support

See also


© 2016 Mozilla Contributors
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

API Method Reference SubtleCrypto WebCrypto API