Re: [clue] Comments on CaptureID and security

[Magnus Westerlund <[e-mail]>]

Hi,

Yes, I think encrypting the CaptureID avoids the negative impacts that 
bad construction can have that I can think of. Thus, I support going in 
that direction.

When it comes to the security solution I would recommend copying the 
text and then make the edits. There is at least two additions, the MUST 
encrypt RTCP, and the MUST implement RFC 6904 and use it to encrypt the 
CaptureID header extension. Please be explicit and clear in the CLUE 
level document on what security solutions that needs to be implemented 
and use.

Reasons for copying the text, is that there are differences between 
RTCWeb and CLUE, and in addition I think the implementation 
considerations and potential needs to later revise the specification are 
different. I am not certain CLUE will want to be required to follow any 
changes that RTCWeb does in the future.

I would also note that I think you need at least to put in a short 
paragraph about the CaptureID value. Something like this.

The construction of the CaptureID value is implementation dependent and 
is not tightly restricted. Therefore there exist a risk that the 
CaptureID contains privacy sensitive information or otherwise revealing 
information about the communication session to third parties. Therefore 
confidentiality protection is always applied to avoid this risk.

Cheers

Magnus

Den 2017-01-18 kl. 10:44, skrev Roni Even:
> Hi, The text I added to the -11 version "The CaptureID is created as
> part of the CLUE protocol.  The CaptId SDES item is used to convey
> the same CaptureID value in the SDES item.  When sending the SDES
> item the security considertion specied in the security section of
> [RFC7941] are applicable and this SDES item MUST use similar security
> as the CLUE protocol messages carried in the CLUE data channel."
>
> Say that  " this SDES item MUST use similar security as the CLUE
> protocol messages carried in the CLUE data channel." The CLUE data
> channel document
> https://tools.ietf.org/html/draft-ietf-clue-datachannel-14#section-4
> point at
> https://tools.ietf.org/html/draft-ietf-rtcweb-data-channel-13#section-7
> pointing to
> https://tools.ietf.org/html/draft-ietf-rtcweb-security-arch-10
>
> So we can reference the rtcweb security architecture or use the text
> I copied from there to define a security profile
>
> As for the second item I agree that if we encrypt the content in the
> CLUE data channel that includes the captureID, we need also to
> encrypt RTCP with the captureID SDES item and it does not matter how
> we create the captureID value, so maybe if we mandate encrypting the
> SDES item there is no strong need for specifying how to create
> CaptureID . Note that the CaptureID is not use to provide
> human-readable textual information which is in the description
> attribute.
>
> Roni
>
>> -----Original Message----- From: Magnus Westerlund
>> [mailto:[e-mail]] Sent: יום ד 18 ינואר 2017
>> 10:45 To: Roni Even; [e-mail] Cc: Jonathan Lennox Subject: Re:
>> Comments on CaptureID and security
>>
>> Hi,
>>
>> A comment about the below. I have an issue raised against the below
>> quoted text from the rtcweb-security-architecture in the RTCWeb WG,
>> as it fails to specify if RTCP encryption is mandatory to use or
>> not. There are protection profiles that only have confidentiality
>> protection for RTP, and not for RTCP. I would recommend requiring
>> confidentiality protection also of RTCP.
>>
>> The second note on the below is that depending on the outcome of
>> the security requirements for the CaptureID RTP header extension,
>> you might in addition have to require RFC 6904, implementation and
>> usage for the CaptureId header extension field. Or rather if you
>> write nothing it will by default be required if you encrypt RTCP,
>> due to RFC 7941. But, I really recommend that you are explicit on
>> this matter. It comes down to what security risks the field
>> entails. What information will it leak to a third party viewer of
>> the RTP/RTCP stream they can capture.
>>
>> Cheers
>>
>> Magnus
>>
>> Den 2017-01-18 kl. 09:33, skrev Roni Even:
>>> 2.       What do we want to say about supported security profile?
>>> For example does the following directive from
>>> https://tools.ietf.org/html/draft-ietf-rtcweb-security-arch-12#section-5.5
>>>
>>>
looks good for CLUE?
>>>
>>>
>>>
>>> “Implementations MUST implement SRTP [RFC3711
>>> <https://tools.ietf.org/html/rfc3711>].  Implementations MUST
>>>
>>> implement DTLS [RFC4347 <https://tools.ietf.org/html/rfc4347>]
>>> and DTLS-SRTP [RFC5763
>>> <https://tools.ietf.org/html/rfc5763>][RFC5764] for
>> SRTP
>>>
>>> keying.  Implementations MUST implement
>>>
>>> [I-D.ietf-tsvwg-sctp-dtls-encaps
>>> <https://tools.ietf.org/html/draft-ietf-rtcweb-security-arch-12#ref-I-
>>
>>>
D.ietf-tsvwg-sctp-dtls-encaps>].
>>>
>>>
>>>
>>> All media channels MUST be secured via SRTP.  Media traffic MUST
>>> NOT
>>>
>>> be sent over plain (unencrypted) RTP; that is, implementations
>>> MUST
>>>
>>> NOT negotiate cipher suites with NULL encryption modes.
>>> DTLS-SRTP
>>>
>>> MUST be offered for every media channel.
>>>
>>>
>>>
>>> All data channels MUST be secured via DTLS.
>>>
>>>
>>>
>>> All implementations MUST implement DTLS 1.0, with the cipher
>>> suite
>>>
>>> TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA with the the P-256 curve
>>>
>>> [FIPS186
>>> <https://tools.ietf.org/html/draft-ietf-rtcweb-security-arch-12#ref-
>>
>>>
FIPS186>].
>>> The DTLS-SRTP protection profile
>>>
>>> SRTP_AES128_CM_HMAC_SHA1_80 MUST be supported for SRTP.
>>>
>>> Implementations SHOULD implement DTLS 1.2 with the
>>>
>>> TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256 cipher suite.
>>>
>>> Implementations MUST favor cipher suites which support PFS over
>>> non-
>>>
>>> PFS cipher suites and SHOULD favor AEAD over non-AEAD cipher
>>> suites.
>>>
>>> “
>>
>>
>> --
>>
>> Magnus Westerlund
>>
>> ----------------------------------------------------------------------
>>
>>
Services, Media and Network features, Ericsson Research EAB/TXM
>> ----------------------------------------------------------------------
>>
>>
Ericsson AB                 | Phone  [phone]
>> Färögatan 6                 | Mobile [phone] SE-164 80
>> Stockholm, Sweden | mailto: [e-mail]
>> ----------------------------------------------------------------------
>
>>
-- 

Magnus Westerlund

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Services, Media and Network features, Ericsson Research EAB/TXM
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Ericsson AB                 | Phone  [phone]
Färögatan 6                 | Mobile [phone]
SE-164 80 Stockholm, Sweden | mailto: [e-mail]
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