End-to-middle Security in SIPdraft-ietf-sipping-e2m-sec-reqs-03

draft-ono-sipping-end2middle-security-02

Kumiko Ono

ono.kumiko@lab.ntt.co.jp

IETF60

Requirements

Changes since 02

• Use cases– Decreased the dependency on session policies discu

ssion. • Requirements

– Closed an open issue whether the proxy server needs to notify the UAS after receiving a response.

• Because there is no such security policies that depends solely on a response.

– Deleted text which belonged to a mechanism.– Changed the requirement for discovery mechanism fr

om proxy-driven to UA-driven.• Security Consideration

– Added text which relates to DoS attack on proxy servers.

Open Issue: the scope

• Is discovery of “middle” overlapping with the scope of the session policy ?– Discussion on the ML– My proposal:

• Yes, they are overlapped in the discovery mechanism. I will add notes that refer to the session policy.

However, e2m mechanism should have a way to notify proxy’s policy using an error message.

Next Steps for e2m-reqs.

• Something missing?

• Ready for WGLC?

Mechanism

Open Issues e2m-mechs.

1. How to discover security policies on “middle”

2. How to label a body for “middle” for inspection only :-)

How to label a body for “middle”

• Option 1: A SIP header and Content-ID MIME header

– This is used in Referred-by mechanism.

• Option 2: A Content-Target MIME header– This is proposed in e2m I-D.

Experimental Data• Environment

– CPU Intel Celeron 2.2GHz– RAM 512MB– INVITE message: 568 bytes– Passing through a proxy server:

41.5 ms– Target data size to be encrypted/

signed: 868 byte• multipart/mime that contains sipf

rag and SDP– Public key size (RSA): 1024bits– CEK size (3DES): 168bits

• S/MIME-secured message size (base64-encoded)– e2e encryption: 2358 bytes– e2e+e2m encryption: 2630bytes

• Performance at a proxy server– Passing through: 47.9ms

– Checking the label and passing through:• Opt1: Label in a new SIP header : +0.1ms • Opt2: Label in a new MIME header: +1.0ms

– Checking the label, decrypting and inspecting a body:

• Opt1: Label in a new SIP header : +8.8ms• Opt2: Label in a new MIME header: +8.4ms

Next Steps for e2m-mechs.

• Is there sufficient interest in the SIPPING WG to continue this work?