Seems like a huge headache with stolen/lost phones, wonder how they handle revokation…
Right maybe should have clarified that. The authentication is facilitated by the trusted middle party aka phone company.
When you log in using this service, you tell using service your phone number. Well their contacted authentication handler (usually one of the phone operators), they forward the request to your operator, who knows to forward it to the phone (as I understand as a network service SMS, like how operators settings updates also get send to the SIM and phone), this service message is handed by the phone cellular interface to the SIM. SIM applet notices “oh this is authentication request”. It displays the session ID of authentication (generated at the original authentication session and displayed there also) and then asks to enter security code to approve (or decline the request)
As such revocation is two fold. First your operator will list the certificate/key invalid. Secondly, since operator is handling the message passing anyway, they know to refuse to send the authentication requests in the first place to the compromised SIM. since as the SIM, that also defines where to send the requests. It is both the independent crypto validation, but also the cell network subscriber identity. Compromised sim stops getting any requests, since it is shutout from cellular connection. Can’t make calls, can’t send and receive texts, since the sim isn’t anymore tied to valid subscriber contact.
Plus with crypto system there is always the option of official public revocation server. Which kind of system is what the national ID smart card system uses. Anyone accepting identifying by those signatures gets told “the official key/certificate/revocation server is this one. Regularly check it for listed revocations by the root trust authority”
Right maybe should have clarified that. The authentication is facilitated by the trusted middle party aka phone company.
When you log in using this service, you tell using service your phone number. Well their contacted authentication handler (usually one of the phone operators), they forward the request to your operator, who knows to forward it to the phone (as I understand as a network service SMS, like how operators settings updates also get send to the SIM and phone), this service message is handed by the phone cellular interface to the SIM. SIM applet notices “oh this is authentication request”. It displays the session ID of authentication (generated at the original authentication session and displayed there also) and then asks to enter security code to approve (or decline the request)
As such revocation is two fold. First your operator will list the certificate/key invalid. Secondly, since operator is handling the message passing anyway, they know to refuse to send the authentication requests in the first place to the compromised SIM. since as the SIM, that also defines where to send the requests. It is both the independent crypto validation, but also the cell network subscriber identity. Compromised sim stops getting any requests, since it is shutout from cellular connection. Can’t make calls, can’t send and receive texts, since the sim isn’t anymore tied to valid subscriber contact.
Plus with crypto system there is always the option of official public revocation server. Which kind of system is what the national ID smart card system uses. Anyone accepting identifying by those signatures gets told “the official key/certificate/revocation server is this one. Regularly check it for listed revocations by the root trust authority”