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Why Google's Wi-Fi Payload Collection Was Inadvertent
Reader Lauren Weinstein found a blog post that gives a good, fairly technical explanation of why Google's collection of Wi-Fi payload data was incidental, and why it's easy to collect Wi-Fi payload data accidentally in the course of mapping Wi-Fi access points. "Although some people are suspicious of their explanation, Google is almost certainly telling the truth when it claims it was an accident. The technology for Wi-Fi scanning means it's easy to inadvertently capture too much information, and be unaware of it. ... It's really easy to protect your data: simply turn on WPA. This completely stops Google (or anybody else) from spying on your private data. ... Laws against this won't stop the bad guys (hackers). They will only unfairly punish good guys (like Google) whenever they make a mistake. ... [A]nybody who has experience in Wi-Fi mapping would believe Google. Data packets help Google find more access-points and triangulate them, yet the payload of the packets do nothing useful for Google because they are only fragments."
The argument is that capturing data packets is useful to find the SSID of access points which send beacon frames with blank SSID field or where only a client is within range but not the access point itself. That argument is bogus. The mobile devices which will later use the mapped SSIDs and BSSIDs to calculate their own position do not see anything but the beacon frames. It is therefore entirely sufficient to capture just the beacon frames.
There is a legitimate argument that Google was just lazy (or "scientific") by capturing everything they can get in the field and analyzing later. There is however no technical reason for this and we should not make one up to defend Google.
Despite what everyone thinks (and how it seems to the uninformed) it very likely was accidental. If I was tasked to correlate Access Points to their locations, the simplest way would be to dump raw wireless traffic to one file, and raw GPS data to another. Later, you can zip them both up and run some analysis, and get the data you want out.
It'd be real easy to forget to filter the packets you dump to only anonymous, non-data-carrying packets. More than likely the people who designed it just forgot to, or figured it would be no big deal if they just never used that info. Sloppy engineering maybe, but certainly not malicious.
Yes, they should have only saved the SSID, location, and signal strength. Instead, they used off the shelf software which saved more data. There is no reason to believe this was intentional.
That's fine and legal to do in the USA, as you have no expectation of privacy using unencrypted broadcast:
http://www.law.cornell.edu/uscode/uscode18/usc_sec_18_00002511----000-.html
TITLE 18 > PART I > CHAPTER 119 > 2511
(g) It shall not be unlawful under this chapter or chapter 121 of this title for any person—
(i) to intercept or access an electronic communication made through an electronic communication system that is configured so that such electronic communication is readily accessible to the general public;
(v) for other users of the same frequency to intercept any radio communication made through a system that utilizes frequencies monitored by individuals engaged in the provision or the use of such system, if such communication is not scrambled or encrypted.
In the US, if you transmit in the clear on unlicensed spectrum, they can legally pick it up due to two different, non-overlapping legal clauses. ( Note, I am not a lawyer, this is not legal advice, this is but one of possibly relevant laws, etc.)
The problem is they didn't need to do so, and it creeps people in the US out. So even here where it is legal, they probably shouldn't have from a PR point of view.
In some other countries it is not legal to collect that data, and doing so intentionally might lower your penalties, but still does not make it legal.
Blessed are the pessimists, for they have made backups.