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Emergency call assurance. Highest-level goals. Protect PSAP resources network resources call takers Protect first-responder resources unnecessary dispatch No worse than today local attack vs. non-local discourage abuse. Threats. (D) DDOS (bots) (L) from within local service area
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Highest-level goals • Protect PSAP resources • network resources • call takers • Protect first-responder resources • unnecessary dispatch • No worse than today • local attack vs. non-local • discourage abuse
Threats • (D) DDOS (bots) • (L) from within local service area • (R) outside local area • (C) Hoax/crank calls (humans) • (L) at correct location • (R) at another (fake) location
Discouragement • Distinguish bots from humans • including silent calls • Catch likely remote (bogus) calls • Catch perpetrators after the call • discourages crank calls
Tools and impact can be signature or transitive trust (reference) • Coarse-grained location assertion • e.g., IP address, provider POP, DSLAM, ... • addresses D/R • Fine-grained location • e.g., geo, street address • can be by value (“signing”) or reference • address C/L • Coarse-grained identity • provider (VSP) • addresses C/R? • Fine-grained identity • responsible party (caller) name & address • may not be useful if outside jurisdiction • addresses D/L, C/L, C/R (some)
Nothing is perfect • Unlikely that every legitimate call will have the “good” bits set (signed, recognizable signer, trusted reference, ...) • Realistic goal is that “almost all” good calls are verifiable • rest is treated as suspicious when call taker resources are available • similar to payphone calls today • and will be lower priority during overload (“ranking”) • Thus, don’t need perfection in any single technique • combination of techniques likely works better • choose easiest-to-deploy • every call should have one at least one “is good” indicator
Deployment scenarios, from easy to hard • ISP = VSP • includes large enterprise • well-known (to PSAP) VSP, well-known ISP • well-known VSP with strong customer authentication • e.g., credit card address (“can sue”) • could be emergency-only VSP • well-known ISP with authentication • well-known ISP without authentication • “unauthenticated network access” • e.g., guest on corporate or home hot spot or public WiFi • unknown ISP/VSP • e.g., out of area (“Sierra Leonian VSP”)
Concerns: Delegation • identity assurance: subscriber identity within service provider • SIP identity, PAI • location signing: within enterprise (room/building level) • ISP customers gets signed LO • includes in calls • or private key to sign own LOs? • enterprise as trusted CA?
Questions: Value or Reference? • sign LO • fine-grained • or get LO from trusted/verifiable source via TLS? • e.g., corporate LIS