RE: Draft blog post for WebCrypto API

Why is this concentrated on the browser and really does not cover the JS devices?

-----Original Message-----
From: Harry Halpin [mailto:hhalpin@w3.org] 
Sent: Wednesday, October 10, 2012 12:32 PM
To: public-webcrypto@w3.org
Subject: Re: Draft blog post for WebCrypto API

Here's the latest version, with Ryan's edits checked in. Last call for edits, otherwise it goes out tomorrow!
------

Title: Re-igniting the Javscript Cryptography Flame War

Recently, the W3C has released as a First Public Working Draft the Web Cryptography API [1], which defines a number of cryptographic primitives to be deployed across browsers and native Javascript environments. As has been discussed in a number of blog-posts [2], cryptography in Javascript on the Web is unsafe at best today, although technically the Web Crypto API is a WebIDL that could be bound to programming languages beyond Javascript. Even with excellent implementations such as the Stanford Javascript Crypto Library [3], browsers still have to download possibly untrusted Javascript cryptographic code obtain basic cryptographic functionality not provided natively by Javascript such as key storage.

Yet is Javascript cryptography doomed on the Web? Much of the critique of Javascript cryptography boils down to a critique of current Web browsers, and as has been shown by the W3C and browser vendors - the Web Platform can evolve. Due to TLS, almost every web browser and operating system already contains well-verified and reviewed cryptographic algorithms. At its core, the Web Cryptography API will simply expose this functionality to WebApp developers, with a focus on essential features such as cryptographically strong random number generation, constant-time cryptographic primitives, and a secure keystore. Without these functions, Javascript web cryptography would be impossible.

Yet we realize the Web Cryptography API is only a single component in building the emerging Web Security model.  For example,  one open issue is whether or not applications using the Web Cryptography API also should be required to use CSP to prevent XSS attacks [4]. Indeed, should and can browser vendors and the W3C as a whole tackle the malleability of the browser Javascript run-time environment? Without a doubt these security considerations of utmost importance, and getting them right to enable cryptography on the Web will require holistic thinking about attack surfaces and threat models. There are a number of use-cases, such as checking digital signatures to out-of-band key provisioning, that our API hopes to enables by allowing key-based encryption and trust to be used in Web applications.

One issue with the Web Cryptography API is that the Working Group decided to expose the low-level functionality first rather than aiming only for a high-level API aimed at the developer on the street who may not have a grasp of the finer details of cryptography. The Working Group did this on purpose after taking a survey of users [5], in order to allow experienced developers to build the functionality needed across the largest number of use-cases, but a "high-level" API that makes using cryptography easy for Web developers is still on our agenda. However, the Working Group decided to iron out the low-level details, in particular as regards keys and key storage, before moving to thinking about a higher-level and more simple API.

A second issue is that the current Web Cryptography API exposes legacy cryptographic algorithms that can be used and implemented insecurely, yet these are still needed in order to allow Web Application developers to create applications with interoperability with widely used applications such as GPG, SSH, and the like. In our next iteration of the Web Cryptography API, we will include appropriate security considerations to try and ensure that web developers do not mistakenly use cryptographic algorithms with known flaws. However, as cryptography is a moving field, we cannot guarantee that today's robust and secure solution will not be tomorrow's security considerations.

Is releasing this cryptography in Javascript to developers responsible?  
Of course, cryptography can be used for both great good and great harm. 
Yet given the current dangerously insecure state of Javascript cryptography and the fact that developers are already re-implementing cryptographic functions in Javascript, I thought that action should be taken. Yet who I'm really interested is not what the W3C thinks, but what the wider community thinks.

The entire point of releasing a Working Draft is to get the wider input of the community before we set the API in stone by implementing it. 
Indeed, we purposefully released the API at an early stage, when many of the basic issues are still unresolved, in order to get community input. 
Indeed, most of the work of the Working Group has been on identifying the space of unresolved issues, ranging from how to determine where a key is stored and key naming. Many of these open issues are given in the fourteen open issues in the specification itself, with more in the issue-tracker [6]. What we really want is detailed comments about the space of design issues, in particular those currently listed as open issues. Also additional use-cases and development of current use-cases would be appreciated, which are currently being stored on our wiki [7].

  So please take the time to carefully review the First Public Working Draft and send comments to the public-webcrypto-comments@w3.org mailing list, where we will respond to you!

[1]http://www.w3.org/TR/2012/WD-WebCryptoAPI-20120913/
[2]http://www.matasano.com/articles/javascript-cryptography/
[3]http://crypto.stanford.edu/sjcl/
[4]http://www.w3.org/TR/CSP/
[5]http://www.w3.org/2012/webcrypto/wiki/SurveyAnalysis
[6]http://www.w3.org/2012/webcrypto/track
[7]http://www.w3.org/2012/webcrypto/wiki/Use_Cases


On 10/10/2012 07:57 PM, Thomas Roessler wrote:
> Any follow up? What's the current state of the blog post?
>
> --
> Thomas Roessler, W3C  (mobile) <tlr@w3.org>
>
>
>
> On 8 Oct 2012, at 20:55, Thomas Roessler <tlr@w3.org> wrote:
>
>> To this specific point:
>>
>>>> So you want a reference to the Web-Origin/Same-origin concept? That's fine.  I think that would fit in the next paragraph though, along with general concerns about Javascript.
>> To be clear, I'd suggest you think about my questions about the Web security architecture in terms of this paper:
>>     
>> http://www.adambarth.com/papers/2010/akhawe-barth-lam-mitchell-song.p
>> df
>>
>>
>>

Received on Wednesday, 10 October 2012 19:47:49 UTC