W3C home > Mailing lists > Public > public-webcrypto@w3.org > August 2012

ACTION-23: Find out status of getrandom in HTML5

From: Harry Halpin <hhalpin@w3.org>
Date: Mon, 20 Aug 2012 15:46:13 +0200
Message-ID: <50323FA5.8090106@w3.org>
To: "public-webcrypto@w3.org" <public-webcrypto@w3.org>, mike@w3.org
[cc'ing Mike Smith from HTML WG]

I believe from our last meeting that Wan-Teh Chan was concerned over the 
use of a non-cryptographic PRG RC4 in the WHATWG spec and filed a bug, 
and I think it was removed [2]. Also, there has been general concern in 
the blogosphere, as exemplified by this Matsuno blog post [1], that 
large random number generation in Javascript is currently broken. 
However, I suspect this all goes back to Math.random(), which is not 
part of HTML and not what we will encourage people to use (if they 
really need to go this low-level!), but instead we will focus on 
window.crypto.getRandomValues() [2].

However, I do think the WG needs to carefully consider the issues (of 
which random number generation is a small part) brought up by the 
Matsuno blog post and others to make sure what the WebCrypto WG produces 
actually has reasonable security properties. So let's make sure we have 
secure PRG across all browsers.

So everyone, what's the status of window.crypto.getRandomValues() is as 
regards cross-browser support, either currently or in the future? I see 
Mozilla is still trying to get a secure PRG exposed on the DOM [3]. Does 
each browser now produce cryptographically strong PRG? Does that include 
IE and Opera?

If there are no problems except the use of RC4 in HTML5, I can consider 
this action closed.

If there some possible problems, we as a WG need to suggest text for the 
WHATWG/HTML5 effort and our own spec to address PRG concerns in Javascript.

    cheers,
         harry

[1] http://www.matasano.com/articles/javascript-cryptography/
[2] http://wiki.whatwg.org/wiki/Crypto
[3] https://bugzilla.mozilla.org/show_bug.cgi?id=440046
Received on Monday, 20 August 2012 13:46:34 UTC

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