Re: [Perc] PERC LIte

[Sergio Garcia Murillo <[e-mail]>]

Hi Mo,

The key in JS is just for the media cencryption, DTLS/SRTP is setup 
normally on top, so it is in no way less secure than current DTLS/SRTP.

If JS is compromised, and an attacker gets the key, he will still be 
unable to access the media data as is encrypted HBH by DTLS. To gain 
access to the media, he would need to get the key AND break HBH DTLS.

Also, if JS is compromised, PERC will be defeated completely (any 
solution) as it could clone all the media streams and sent it to a rogue 
MD with a different PC.

To prevent that is why IdP was introduced into WebRTC, and a similar 
solution could be done for setting the key (just run a js script from 
the KD on an independent context and restrict the usage of that stream 
to the required identity).

Anyway, I understand this will be a sensible topic, so I am willing to 
discuss this in detail.

Best regards
Sergio



On 24/05/2017 23:42, Mo Zanaty (mzanaty) wrote:
> Keys in JS app signaling/APIs??? Have we come full circle back to SDES???
>
> Seems like PERC lite would weaken not strengthen the security of 
> DTLS-SRTP / WebRTC apps, if JS can inject keys to ignore DH, defeat 
> PFS, etc.
>
> Confused,
> Mo
>
> From: Perc <[e-mail] <mailto:[e-mail]>> on 
> behalf of Alexandre GOUAILLARD <[e-mail] 
> <mailto:[e-mail]>>
> Date: Wednesday, May 24, 2017 at 5:14 PM
> To: Sergio Murillo <[e-mail] 
> <mailto:[e-mail]>>
> Cc: "[e-mail] <mailto:[e-mail]>" <[e-mail] 
> <mailto:[e-mail]>>, Bernard Aboba <[e-mail] 
> <mailto:[e-mail]>>
> Subject: Re: [Perc] PERC LIte
>
> bernard,
>
> Good point.
>
> i'm discussing with peter T, and proposal for webrtc WG and ORTC CG 
> API extensions are coming your way this week.  Sergio did it at the 
> PeerConnection level while peter is advocating an Api at the 
> RTPSender/Receiver level. Of course, the crypto-algorithm needs to be 
> an input variable as well.
>
> On Thu, May 25, 2017 at 5:46 AM, Sergio Garcia Murillo 
> <[e-mail] 
> <mailto:[e-mail]>> wrote:
>
>     Hi Bernard,
>
>     Yes, the example API is just the lazy approach I have taken on my
>     modified chromium, hardcoding the key to AES-GCM 256 so I didn't
>     have to add an object to the IDL and worry about how to retrieve
>     later on the c++ code.
>
>     The API should allow to set the key and look more like:
>
>     *
>
>     const pc = new RTCPeerConnection({
>
>     mediaCrypto : {
>
>     key : 'VEhJUyBJUyBUSEUgMzIgS0VZIFdJVEggMTIgU0FMVCBET1VCTEUgUEVSQyE=',
>
>     suite  : 'AEAD_AES_256_GCM'
>
>     }
>
>     });* Anticipating the security comments, I don't expect that to be
>     the final API for WebRTC, which IMHO should be a similar mechanism
>     as the one in place for IdP (or even integrated with it), but I
>     feel that that discussion should take place on the RTCWeb group
>     and not here. Best regardsSergio
>     On 24/05/2017 19:56, Bernard Aboba wrote:
>>     Thanks for posting this.
>>     Question:  In terms of API support, how is the crypto-algorithm
>>     specified?  So far, the proposed API just has the key.
>>     On Wed, May 24, 2017 at 10:11 AM, Sergio Garcia Murillo
>>     <[e-mail]
>>     <mailto:[e-mail]>> wrote:
>>
>>         Hi all again,
>>
>>         Also to start the discussion about 5), I would like to
>>         introduce again my proposal for a "PERC Lite" approach.
>>
>>         The main objectives and key points of this proposal are:
>>
>>           * Minimum viable PERC implementation
>>           * Minimize impact on both endpoints and MD
>>           * OHB is carried in the RTP payload (Encrypted Payload
>>             Header).
>>           * No changes to the DTLS/SRTP code/api/standards
>>           * No RTP E2E Header extensions
>>           * RTX/FEC/RED is supported HBH without any change to
>>             current standards/implementations. 
>>
>>         Best regards
>>
>>         Sergio
>>
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>>
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> -- 
> Alex. Gouaillard, PhD, PhD, MBA
> ------------------------------------------------------------------------------------
> President - CoSMo Software Consulting, Singapore
> ------------------------------------------------------------------------------------
> sg.linkedin.com/agouaillard <http://sg.linkedin.com/agouaillard>
>
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