Re: [OpenCoin-devel] Fwd: [GSoC-2015] OpenCoin Digital Cash App

[Nils T. <ni...@op...>]

On 01.04.2015 17:08, Tom Salfield wrote:
> Happy to be the messenger of good news for OpenCoin. So, why don't we
> encourage these GSOC students to try to build a browser wallet?

+1!


> I'd assume that the only thing holding this back was the lack of a
> proper RNG 

That, and access to fast BigInt for blinding.


> - I think that is the conclusion we came to a couple of years
> ago. Possibly the speed of browsers a few years ago may have also been
> prohibitive.
> 
> I'm not sure about the exact consistency of WebCryto API implementations
> of higher level protocols (RSA, AES etc).
> 
> I'm currently using standard javascript implementations of AES, ChaCha,
> SHA512, SHA256 implementations without any real speed issues. I'm sure
> asymmetric algorithms pose much greater performance issues. 

They usually do. See this thread for some benchmark results on phones
where the blinding BigInt is done in standard java script:

   http://sourceforge.net/p/opencoin/mailman/message/30169063/

Now that might not have been the most efficient BigInt lib available,
and phone CPUs got faster since then, but i still expect 2048bit
blinding to be laggy without native BigInt support.


> However, I
> believe this can be much faster when leveraging asm.js - though I
> haven't used the library I referenced earlier.
> 
> In that case, I'm not convinced that there is too much value in using
> the web-crypto versions of RSA/AES etc, seems likely that it won't be
> much more efficient - and you have to trust ALL the browser vendors to
> implement it securely, rather than a single implementation across all
> browsers.

It's probably up to the developers which library they prefers to use.


>> So use BigInt from ASM, the RNG from WebCrypto, RSA and other primitives
>> from either and bang there you have all you need! :-)
>>
>> Nice to learn that the stuff we've been waiting for for many years have
>> *finally* made it into the release-version of all major browsers. *phew*
> 
> Just to be clear, afaik there is no BigInt in asm.js, it is just
> implemented in the library using asm.js 

Oh. Does that mean that there is still no accelerated BigInt in
browsers? That would throw us back again :-(


> - nothing stopped anyone from
> implementing such a library without asm.js in plain javascript - and
> such libraries have long existed.

In know, we use(d) them. They are slow.


>>> No support in less than IE11, though you could seed a pseudo-random
>>> number generator with a random seed from a server request - I think -
>>> but feels riskier.
>> That would mean to trust the server, which is (trust-wise) equivalent to
>> doing all crypto server-side in the first place. Not really an option.
>>
> Right, I guess that is true in the OpenCoin case - since the blinding is
> dependent on the RNG. Its not the case for all crypto purposes, for
> example when generating a nonce for AES, we are able to encrypt data in
> the browser without ever sending the key to the server. If the nonce
> were compromised it wouldn't be good - but it isn't equivalent to doing
> all the crypto server-side.

Agreed. I was only referring to OpenCoin, i should have made that clear.

/n


>>> Give me a call if you are ever in London
>> Will do!
>>
>> x/n
>>
>>
>>
>>> Tom x
>>>
>>>
>>>
>>> On 01/04/15 14:41, Nils Toedtmann wrote:
>>>> Re-reading http://sourceforge.net/p/opencoin/mailman/message/31090382/
>>>> it looks like the issue was not lack of BigInt support (that was an
>>>> issue with WebCrypto, not ASM), but crypto-grade randomness.
>>>>
>>>> That was almost 2 years ago. Has that improved? Or is there some other
>>>> source for quality randomness in modern browsers?
>>>>
>>>> /n
>>>>
>>>>
>>>> On 01.04.2015 14:31, Nils Toedtmann wrote:
>>>>> On 01.04.2015 14:28, Nils Toedtmann wrote:
>>>>>> Hi Tom!
>>>>>>
>>>>>> I vaguely remember - but i might be wrong - that there is an important
>>>>>> crypto primitive missing, and that is blinding/unblinding. And
>>>>>> unfortunatly the API is only exposing crypto primitives, but not the
>>>>>> underlying BigInt library, so you have to do it outside JS - which is
>>>>>                                                  ^^^^^^^^^^^^^
>>>>> Typo. I meant outside ASM
>>>>>
>>>>>> pretty slow.
>>>>>>
>>>>>> I think i even had conversations with the webcrypto gang about this.
>>>>>> Will try to find it when i have more time.
>>>>>>
>>>>>> /n
>>>>>>
>>>>>>
>>>>>> On 01.04.2015 13:15, Tom Salfield wrote:
>>>>>>> Hi Stefan,
>>>>>>>
>>>>>>> On 15/03/15 21:41, Stefan Xenon wrote:
>>>>>>>> A while ago we did some tests and found that native JS may be
>>>>>>>> problematic because it is very slow for some of our crypto operations.
>>>>>>>> We concluded that a native "module" would be a good choice when using
>>>>>>>> Phonegap. This module would be native platform code (e.g. Java for
>>>>>>>> Android) and perform the crypto calculation. Do you have experience in
>>>>>>>> using such?
>>>>>>> Out of interest what were the performance problems in doing this using
>>>>>>> browser crypto? I'd have thought that with faster browsers, and built in
>>>>>>> random number generation this should perform quite well by now. In
>>>>>>> firefox and chrome and probably IE12 there is asm.js support - making
>>>>>>> implementations potentially significantly faster:
>>>>>>>
>>>>>>> https://github.com/vibornoff/asmcrypto.js/tree/master/src
>>>>>>>
>>>>>>> Anyway, just interested to know where the bottleneck would be?
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Tom
>>>>>>>
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>