Secure SIP? Do It Yourself! OpenFortress* digital signatures

Transcription

1 Secure SIP? Do It Yourself! OpenFortress digital signatures

2 why divert from pots? Slow to accept change: Immobile numbers Switch to voic after N rings Caller-ID limitations Limited lingo: Voltage/frequency bursts Rigid bureaucracy: One supplier at any time Supplier switching difficulties Payment contracts between suppliers sipsecure intro OpenFortress

3 why switch to sip? SIP is the VoIP that can be as global as POTS It feels like POTS++ The world can upgrade gradually (DID, DOD, ENUM) Domain-based telephony (like ) Manufacturers aim at interoperability Unconstrained signalling lingo Broader media lingo (video, whiteboard, games) Call routing with the flexibity of the Internet More control over telephony sipsecure intro OpenFortress

4 annoying cheap sip SIP is sold as a cheap way to call More importantly, SIP can help to bypass POTS SIP networks are not being interconnected customers are kept ignorant but SIP was never intended to be confined! sipsecure intro cheap OpenFortress

5 annoying cheap sip OpenFortress is developing 0cpm.nl SIP-calls are connected directly non-sip calls are relayed to an upstream provider SIP calls at a guaranteed rate of 0 ct/min Aiming to connect as many domains/suppliers as possible Revolutionary pricing model: Charge only a SIP setup fee sipsecure intro cheap OpenFortress

6 why secure sip? Login is already protected Privacy yours your customer s Authenticity Caller-ID on POTS is reliable SIP needs authentication for that sipsecure security OpenFortress

7 sip and security Common SIP is: Lookups over DNS Signalling over UDP Media over RTP/UDP Not at all secure! sipsecure security OpenFortress

8 sip and security Formally, SIP is: Lookups over DNS or DNSsec Signalling over UDP, TCP or TLS Media over RTP/UDP with encryption options Potentially secure! sipsecure security OpenFortress

9 problems with secure sip TLS is just transport protection Wiretapping in civilised countries sipsecure security OpenFortress

10 tls is just transport protection Positive: TLS is not optional for SIP proxies conform RFC 3261 TLS could protect media encryption keys Negative: TLS protects connections between SIP proxies Most SIP-traffic passes through a number of proxies Reliance on all their trusted certificate lists sipsecure security tls4sip OpenFortress

11 wiretaps in the netherlands Public telephony providers must support taps Provider s encryption must be removed upon delivery Signalling party is responsible Wiretaps make TLS-security useless for privacy Only end-to-end encryption is really private No laws against explaining such encryption :-) sipsecure security wiretapping OpenFortress

12 solution (1) do not rely on vendors They must tap your traffic They won t support SIPS They probably filter out S/MIME attachments sipsecure solution OpenFortress

13 solution (2) do it yourself You alone can setup end-to-end encryption Welcome SRTP media on trusted networks Get a suitable telephone or media proxy Consider S/MIME for SRTP key exchange? NAT problems... Proxies may strip it off... sipsecure solution OpenFortress

14 solution (2) do it yourself Use your domain: Avoids POTS (and its related services) Use DNSsec or /etc/hosts By all means, both SIDN about DNSsec! SIP uses DNS SRV so /etc/hosts is not enough Accept TLS-based calls on a trusted network Possibly setup a translating proxy sipsecure solution OpenFortress

15 conclusions Secure SIP is good for privacy, authenticity Security is more important for SIP than for POTS Do not rely on a provider for Secure SIP Setup a few gateways yourself sipsecure conclusions OpenFortress

16 OpenFortress digital signatures