Create SHA-256 hash from a Blob/File in javascript

Question

I need to create a SHA-256 digest from a file (~6MB) inside the browser. The only way that I've managed to do it so far was like this:

var reader = new FileReader(); reader.onload = function() {     // this gets read of the mime-type data header     var actual_contents = reader.result.slice(reader.result.indexOf(',') + 1);     var what_i_need = new jsSHA(actual_contents, "B64").getHash("SHA-256", "HEX"); } reader.readAsDataURL(some_file); 

While this works correctly, the problem is that it's very slow. It took ~2-3 seconds for a 6MB file. How can I improve this?

Answer 1

You may want to take a look at the Stanford JS Crypto Library

GitHub

Website with Examples

From the website:

SJCL is secure. It uses the industry-standard AES algorithm at 128, 192 or 256 bits; the SHA256 hash function; the HMAC authentication code; the PBKDF2 password strengthener; and the CCM and OCB authenticated-encryption modes.

SJCL has a test page that shows how long it will take.

184 milliseconds for a SHA256 iterative. And 50 milliseconds for a SHA-256 from catameringue.

Test page

Sample code:

Encrypt data: sjcl.encrypt("password", "data")

Decrypt data: sjcl.decrypt("password", "encrypted-data")

Answer 2

This is an old question but I thought it's worth noting that asmCrypto is significantly faster than jsSHA, and faster than CryptoJS and SJCL

https://github.com/vibornoff/asmcrypto.js/

There is also a lite version (a fork of the above) maintained by OpenPGP.js

https://github.com/openpgpjs/asmcrypto-lite

Which only includes SHA256, and a couple of AES features.

To use asmCrypto You can simply do the following:

var sha256HexValue = asmCrypto.SHA256.hex(myArraybuffer);

I'm able to hash a 150MB+ file in < 2 seconds consistently in Chrome.