Tuesday, July 28, 2020

Really useful networking efforts, and their opposites.

My  favourite group currently working on internet stuff around the ietf is 
GAIA which is delivering lots of useful information about shared initiatives to provide meaningful and relevant internet access and services (see especially work on affordable community networks, and reducing misinformation, e.g. on covid in the minutes&slides linked above).

In contrast, the race for 5G, and now even 6G is driven, it seems to me, almost entirely by greed and a nlatant disregard for anything remotely sustainable or fairly offered (as per, William Gibson's "the future is already here, it is just unevenly distributed").

For example, we were looking at various mobile apps for covid-19 that might help mitigate the pandemic, and concluded that very few would be in the least bit viable in the developing world.  The GAIA folks are heading a long way to helping with that. Quite frankly, the 6G folks are going the opposite direction.

Wednesday, July 22, 2020

confusion regarding privacy of decentralised ("gapple") based BLE contact tracing apps

various publications report problems with the (e.g. swiss, german, irish) contact tracing apps privacy model confusing OS (what apple&google can and do do with location services and networks) and apps.

I suggest people read the app code (the irish have very kindly open sourced the HSE app for the world. even more helpfully, their leading researchers have actually measured what data is sent by different european contact tracing apps so you can see what is and is not the case about your privacy.

more light and less heat, please:-)

also comments on the efficacy of decentralised apps (do they work) can be countered with the observation that what you care about is the number of people notified that test positive, and that can be done when people notified ask for a test (you could even get the history of RSSI/BLE readings from them without re-identifying the phone random decentraslised id magic at that point, and run stats, which would be more time consuming than centralized log analysis, but would eventually let you re-calibrate your BLE algorithm to maximise effectiveness) - remember, we dont actually care about the distance between phones, we care about the true positive infection detection/notify/isolate rate, and we care about minimising false negative proximity so you don't end up isolating zillions of people and might as well go back to lockdown....).

Thursday, July 09, 2020

update on centralised v. decentralised contact tracing apps....deconstructing who distrusts whom?

one of the reasons oft-cited for the centralised design of the original UK NHSX contact tracing app was
the lack of testing for people, due to the governments decision (failure) to continue/expand/rol out systems (despite offers from quite a few research labs that had large capacity systems ready to roll).

Instead, the assumption was that people would "self report" with symptoms (or diagnosed after a 111 call) - not only might these be unreliable, they might attract abuse (troll like behaviour is fairly common). Hence one goal was that the index case should be trackable and (presumably) potentially blocked /reported if multiple bogus attempts made to claim a) they were infected and therefore b) cause a lot of people in their contactee data to have to self isolate pointlessly for 7+ days.

I'll note here that tests on the contactees dont help set them free, because recently infected people don't typically test positive for virus until they have symptoms (pre-symptomatic) and note, a significant fraction won't ever get symptoms even if infected (asymptomatic, and are still potentially infectious even if apparently well. Indeed - there arre good public health reasons to measure the rate of asymptomatic infectious people as this is part of the risk level in an area.

Thus, as well as wishing to improve any diagnosis menus in an app, and as well as desiring to continuously improve the exposure notification algorithm used to turn BLE measurements into a likelihood of possible infection, we also have the wish to record who (non anonymously) claimed infection, and who (possibly anonymously, but re-linkably in a chain of infections) was a contactee without symptoms, for epidemiological reasons, as well as for notification.

As well as this, it would be useful to know the context (location, e.g. indoors, in vehicle, type of building versus out doors) and whether in only a pairwise encounter, or a group - all this data helps understand the modes that the virus spreads through, to help sharpen advice to the public, and also refine the algorithms.

There's some discussion about why one would combine these two functions in one app (contact notification and public health statistics). There are quite a few nice symptom reporting apps (notably in the UK joinzoe), which do a good job of learning new symptoms' importance, and can map hotspots over time as well) - but the point is that it is not a change to a centralised app to provide the contact graph of infected people - this is the same primary purpose - the "second" application is simply the use of the stored data and doesn't change the app at all. In fact, the notification service is also notably simpler if you don't need to build some magic decentralised rendezvous network. 
I notify service I am diagnosed positive with list of contacts. service notifies each contact they may have been exposed (potentially with human in the loop to detoxify the bad news).

so what are the trust problems here? well by not having testing and not trusting the users to all only honestly report symptoms, the government/UK health service set a tone that the customer is not always right. But the decentralised systems send the message that the public don't trust the national health service in their country, and yet they have to trust that health service if they fall ill, so this is a hidden toxic message too.

don't be too surprised if both systems lead to a rise in distrust of health science, and potentially a boost to the anti-vaxxer movement, just at a time when we may really need to get vaccinated.

the good thing is that when we have a vaccine, unlike with smallpox or polio, we don't need to create (true) herd immunity immediately, but rather need only vaccinate the vulnerable, at least at first. Of course, there may be a novel novel corona virus around the corner which goes back to the mortality risk levels of SARS and MERS but has the incubation time of Covid-19, and then we'd really care that a lot of people were out of the infection loop proactively (not reactively).

For now, reacting as fast as possible is our best bet to get as close to zero cases as possible..

Friday, July 03, 2020

net values gross laws

there are a bunch of laws of the value, or utility of a network - all these assume a set of n nodes (presumably owned each by one user), all effectively connected to all other users. That doesn't mean there is a "full mesh" network (with n^2 links) - just the capability of communication from each to every other node. 

i'm not stuck on any particular "layer" of communications here - for those not familiar with the marvellous seven layer model of communications (or variants) we could be talking about physical or internet or application layer here - if you like, we're talking wires, versus who's in your contact list, versus who you can get to on facebook or zoom or whose blog you can read, etc

Lets leave aside annoying things like NATs (and ADSL and most cellular links) that are asymmetric - there are workarounds for that anyhow. Well, let's not leave that aside, as asymmetry of a communications service is part of why there are different laws. this matters, as constraints on who you can talk to aren't just about censorship. they create "walled gardens" - a phrase I hate as the implication is that all is well in the garden : it isn't - there's no supply of water or seeds or bees or anything to keep the garden alive. it isn't a garden. its a desert. facebook is a desert. or an elephants graveyard, where old things go to die.

metcalfe's law 
so if you have a network of 12 people, its utility is 144
since that's the total number of connections possible - for each of the 12 people, 
they can talk to 12 other people. They may not want to, but they could. I think metcalfe was getting at something more nuanced than this - I think he has been a proponent of super-linear economic growth that underpinned some teechno-evangelism from the left coast. I like it because it captures an essential idea of the Internet inherrent in always on, always reachable, and extensible. Anyone could run a server. anyone could write a server. my interpretation of this model is that it is about affordance of the capability of endless addition of new applications from anyone anywhere anytime, that anyone else can use.

reed's law
so if you have a network of 12 people, its collective potential is 4096
since thats the set of all possible subsets of people that can form.
I think reed took the same interprretation that I have, but is even more enthusiastic, but at the same time, captures the idea that new applications may be of niche interest.  the value of the network in both metcalfe and reed's models is a value that accrues to all the users - providers ('lower levels') cannot explicit this value in the same scale, because that would kill the incentive for people to create all these new apps - the entry cost would be too high, the return too low. there is no tax levy on service that could be set which would do anything else. kill the goose that laid the golden egg. I'd note that there's still a golden egg (see next laws) because more people still means more revenue as each still pay a recurrent fee, and more apps may mean more bandwidth so capacity deployed still always (in the end) will make money.

briscoe's law
with a network of 12 people, your service utility is 29.82 (approx)
briscoe's taking a plausible model which I think is more about revenue  that can be made by a serrvice provider, offereing connectivity to a higher layer. Note it is still super-linear, and I am not completely convinced this makes sense.

jon's complaint (sarnoff's law)
so with a network of 12 people, the provider's service is worth 12 units. sarnoff devised this for broadcast networks. Broadcast systems are massively asymmetric - there's a broadcaster (often using radio/tv/satellite etc) that reaches a lot of people. hHey often get in the business of content creation (or at least sponsorship - e.g. for sports, but nowadays, for internet streaming/download too - Amazon, Netflix join the BBC, Disney etc  - securing their supply chain, etc)

I'm going to try to explain why  these are all not wrong, although, like many models, they may or may not be useful.

I claim that the internet is mostly behaving like Sarnoff's law now. we can't create new services. Not because of network effects (people on old services can't shift to the new one is not a strictly correct barrier - people went from myspace to facebook, from twitter to tiktok, but they had to do so additively. not multiplicatively - having 10 social networks or 10 video conferencing apps is 100 times less valuable than having 1 that reaches all the people that are divided by those barriers. (insert old joke about america and england being two great nations divided by a common language).

the cost of writing a new app, creating a new service is tiny. it immediately would get value if  it was possible to deploy, but long gone are the days of Metcalfe or Reed's idealised Internet. barriers to deployment exist at all levels. the wires are not open, the address books are not all equal. Apps to not afford access to other apps the way email and the web permitted arbitrary extensibility and innovation.

what's more, the stultification of the growth in new systems that can reach anyone and everyone also means that the very bottom of the system, the wires, where there is never any hope of getting more value than n for n users, is getting less. that is a great example of the poisoning of the geese.

...and they aren't laws, they are models...

I'm going to try to explain why  these are all not wrong, although, like many models, they may or may not be useful.

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misery me, there is a floccipaucinihilipilification (*) of chronsynclastic infundibuli in these parts and I must therefore refer you to frank zappa instead, and go home