Re: [rtcweb] SRTP requirement - wiretapping (Re: Let's define the purpose of WebRTC)

Ravindran Parthasarathi <> Wed, 09 November 2011 01:21 UTC

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From: Ravindran Parthasarathi <>
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Thread-Topic: SRTP requirement - wiretapping (Re: [rtcweb] Let's define the purpose of WebRTC)
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Date: Wed, 9 Nov 2011 01:21:46 +0000
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Subject: Re: [rtcweb] SRTP requirement - wiretapping (Re: Let's define the purpose of WebRTC)
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Thanks to Harald/Cullen for pointing out RFC 2804. I take back my #2 comment based on RFC 2804 wiretapping policy. 

I wish to clarify why I gave this comment before closing on #2:

It is the common practice in India to buy computer to talk/chat with the relatives who are outside India by using Skype/Gtalk/Yahoo (avoiding International subscriber dialing charges). Of course, Cell phone is more popular than Computer and cheap (~$100) Wi-Fi enabled (Android) Smartphones are available in market. WebRTC will bring the new innovative way of communicating using Smartphone (like free WebRTC session to street provisional store). Browser in Smartphone is the platform for making outgoing session towards provisional store. I really don't want these kind of WebRTC service are forbidden by Government laws unnecessarily due to security (SRTP) reasons. 

>-----Original Message-----
>From: Harald Alvestrand []
>Sent: Wednesday, November 09, 2011 3:58 AM
>To: Ravindran Parthasarathi
>Cc: Hadriel Kaplan; Eric Rescorla; <>
>Subject: SRTP requirement - wiretapping (Re: [rtcweb] Let's define the
>purpose of WebRTC)
>Changing the subject again to mention SRTP....
>On 11/08/2011 03:30 PM, Ravindran Parthasarathi wrote:
>> I agree with Hadriel that it is not required to mandate SRTP for
>WebRTC. My reasoning are as follows:
>> 1) Security could be in the lower layer itself (IPsec, VPN, private
>MPLS cloud). For Enterprise-only-WebRTC application (no federation&  no
>interop), there is no need of security by specific application like
>WebRTC as it is ensured in the infrastructure. WebRTC security will be
>duplicated for these infrastructure and may leads double encryption
>This argument makes some sense.
>> 2) Being in India, I'm interested in avoiding Government restriction
>on WebRTC proposal (Thanks to Tim for pointing this). I may not surprise
>to see that WebRTC mechanism is banned in India because intelligent
>agency struggles to break the key in each terrorist WebRTC site.
>This argument is contrary to stated IETF policy (RFC 2804).
>I recommend the RFC for background reading.
>> In case there is no use case to illustrate in RTCWeb draft, let us
>discuss in detail.
>>> -----Original Message-----
>>> From: [] On
>>> Of Hadriel Kaplan
>>> Sent: Monday, November 07, 2011 9:12 PM
>>> To: Eric Rescorla
>>> Cc:<>
>>> Subject: Re: [rtcweb] Let's define the purpose of WebRTC
>>> On 11/07/2011 02:50 PM, Eric Rescorla wrote:
>>>> On Sun, Nov 6, 2011 at 7:20 PM, Hadriel
>>> wrote:
>>>>> Who said "too slow"?  There *is* an extra round-trip or two
>>> I presume, if we're talking DTLS-SRTP, but no I didn't mean that as a
>>> "hit".  I just meant the extra computing cycles for SRTP being a
>>> For WebRTC-to-WebRTC I don't think that matters at all.  For WebRTC-
>>> media-server it might, for a free game app or greeting card app that
>>> don't care about it to begin with, and which use plaintext HTTP to
>>> with.
>>>> Sorry, I didn't mean to put words in your mouth. Performance
>>> measurements
>>>> of HTTP versus HTTPS in modern Web environments suggest that the
>>> additional
>>>> load for HTTPS is not significant. Do you have evidence that the
>>> situation is
>>>> different for SRTP versus RTP?
>>> Only from the DSP guys, and those would be hardware DSPs not
>>> It runs them anywhere from 10-25% overhead, they say, depending on
>>> vendor and what else their DSPs are doing at the time.
>>> But ultimately even in software I assume it's all relative to what
>>> work you're doing.  If you have to render a video stream on a screen
>>> encode camera input into a codec being sent out, then my guess is
>>> overhead is a tiny factor not worth talking about.  If you're mixing
>>> multiple RTP streams as a conference server, then I assume doing SRTP
>>> for thousands of simultaneous audio RTP streams for multiple
>>> simultaneous conferences becomes noticeable.  Or at least so they
>>> to claim - I don't know since I don't build a media server (hardware
>>> SBCs often offload SRTP onto dedicated hardware).  One large software
>>> company even created their own proprietary packet format for SRTP
>>> they claimed was done for improving performance/scalability, so I
>>> it has some impact they don't want their customers to incur.
>>> -hadriel
>>> _______________________________________________
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