Re:Centralised DoH is bad for privacy
by tialaramex on Thursday September 26, 2019 @09:13AM
(#21080594)
> ONT-OLT communication is typically encrypted as well
Is it? I guess that's conceivable though it looks _optional_ to me, but I have no statistics as to how widely the option is taken up.
Nevertheless the G.948 work basically doesn't care about eavesdroppers. The threat model they've engineered around is that Eve lives next to Bob, and so if she tweaks the ONT (which legally belongs to her ISP but is on her property) she can see Bob's messages, whereas we're talking about a fibre tap to receive everybody's messages and then we'll root through that for Bob's messages.
G.948 as amended makes random keys in each ONT and sends them to the OLT, knowing Eve can't see the key chosen by Bob's ONT (it passes upstream not downstream). But as an eavesdropper with a fibre tap we do see both directions so this countermeasure doesn't inconvenience us.
Good on them for spelling out a threat model, and to me their model seems reasonable (if Alice buys Premium Sports for $180 per month we don't want Bob to watch Premium Sports free by pirating Alice's data) but it doesn't stop bad guys snooping this traffic.
Is it? I guess that's conceivable though it looks _optional_ to me, but I have no statistics as to how widely the option is taken up.
Nevertheless the G.948 work basically doesn't care about eavesdroppers. The threat model they've engineered around is that Eve lives next to Bob, and so if she tweaks the ONT (which legally belongs to her ISP but is on her property) she can see Bob's messages, whereas we're talking about a fibre tap to receive everybody's messages and then we'll root through that for Bob's messages.
G.948 as amended makes random keys in each ONT and sends them to the OLT, knowing Eve can't see the key chosen by Bob's ONT (it passes upstream not downstream). But as an eavesdropper with a fibre tap we do see both directions so this countermeasure doesn't inconvenience us.
Good on them for spelling out a threat model, and to me their model seems reasonable (if Alice buys Premium Sports for $180 per month we don't want Bob to watch Premium Sports free by pirating Alice's data) but it doesn't stop bad guys snooping this traffic.