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> In March, the Agency awarded a contract to the Telus Data For Good program to provide “de-identified and aggregated data” of movement trends in Canada. The co

> In March, the Agency awarded a contract to the Telus Data For Good program to provide “de-identified and aggregated data” of movement trends in Canada. The contract expired in October, and PHAC no longer has access to the location data, the spokesperson said. So it's anonymized movement data that CSE (probably) already had complete access to. I'd like to know more about how granular the data is. Obviously if it's too granular it just points to your home and the grocery store, which isn't very anonymous. If it is a log of city-to-city travel, then it should be fairly hard to pin point any specific individual from the dataset. I think Apple and Google's device-to-device contact tracing is a much better approach to the locality problem, and it is also in use in Canada (opt-in).

dleslie 5y ago
What does "de-identified" mean, precisely? Does it simply remove the legal name but retain the uniqueness? Ie, can they tell that one person traveled from Victoria, to Vancouver, to the Wetsuweten territory; but not know who, specifically, that person is?
- ipaddr 5y ago
  That's unnecessary. The information they are collecting at travel points (trains/planes/ports) with these vaccine passports they already have that information.
- fennecfoxen 5y ago
  De-identification can mean a lot of things, but when dealing with location histories one at a time, few of them help very much. How many people take the same route that you do to work? How many do it at the same time you went and stopped at the same store on the way back at the same time you did? How many took the same vacations? How many live in the same building? The intersection of these sets very rapidly approaches one person. The question is the extent to which the aggregation obscures all this.
  - 14 5y ago
    How about who had access to it? Did they watch their gf movements while she was out? Will we be seeing down the road that it was abused and a jealous lover tracked their partner? This whole thing has already been played out in history and we know this is a bad thing. I am shocked HN crowd is defending this behaviour this time. This is not something we should accept as a society.
- bushbaba 5y ago
  …or that a person (anonymous unique id) traveled to 123 somewhere road. And stayed there from 8pm through 10am. And the tax records also show a man by the name of Joe who put the same address as their primary residence. Viola! De-anonymization.
  - KMnO4 5y ago
    Okay, but who has access to the full PII of tax records? If the government really wanted deanonymized data, they could just get it directly. Instead, they’re intentionally enforcing a degree of anonymity. Part of that could include preventing those with access to tax records access to this location data as well.
- deleted 5y ago
  [deleted]
sneak 5y ago
There is no way to anonymize movement data. Anyone telling you that location data is "de-identified" or "anonymized" is lying to you.
- arcticbull 5y ago
  Ok but what on earth good is identifiable data to PHAC? Why would PHAC try and de-anonymize this data? What could they possibly do with it? Canadian government entities tend to be well intentioned even if not always the most efficient.
  - robbedpeter 5y ago
    When, not if, they have a data breach, those records are trivially deanonymized by malicious third parties. They shouldn't have the data, they don't need it, and storing it long term is completely unnecessary. Collection of private data is only ever appropriate directly from an individual with informed consent, with strict and mutually agreed upon limits on how long it can be stored and the uses to which it can be put. Permanent or long-term data retention should be rare and have intense oversight. Almost everything else should be ephemeral on the level of minutes to hours. Legislation will catch up after this bites us in the ass, and the longer it takes, the worse it's going to be.
    - arcticbull 5y ago
      > They shouldn't have the data, they don't need it, and storing it long term is completely unnecessary. I mean, I completely disagree. If the job of a public health agency isn't to use anonymous data to make informed decisions about public health what on earth is their job?
      - robbedpeter 5y ago
        They don't need location tracking. It's inherently not anonymous.
        5y ago

dleslie 5y ago

What does "de-identified" mean, precisely? Does it simply remove the legal name but retain the uniqueness? Ie, can they tell that one person traveled from Victoria, to Vancouver, to the Wetsuweten territory; but not know who, specifically, that person is?

ipaddr 5y ago
That's unnecessary. The information they are collecting at travel points (trains/planes/ports) with these vaccine passports they already have that information.
fennecfoxen 5y ago
De-identification can mean a lot of things, but when dealing with location histories one at a time, few of them help very much. How many people take the same route that you do to work? How many do it at the same time you went and stopped at the same store on the way back at the same time you did? How many took the same vacations? How many live in the same building? The intersection of these sets very rapidly approaches one person. The question is the extent to which the aggregation obscures all this.
- 14 5y ago
  How about who had access to it? Did they watch their gf movements while she was out? Will we be seeing down the road that it was abused and a jealous lover tracked their partner? This whole thing has already been played out in history and we know this is a bad thing. I am shocked HN crowd is defending this behaviour this time. This is not something we should accept as a society.
bushbaba 5y ago
…or that a person (anonymous unique id) traveled to 123 somewhere road. And stayed there from 8pm through 10am. And the tax records also show a man by the name of Joe who put the same address as their primary residence. Viola! De-anonymization.
- KMnO4 5y ago
  Okay, but who has access to the full PII of tax records? If the government really wanted deanonymized data, they could just get it directly. Instead, they’re intentionally enforcing a degree of anonymity. Part of that could include preventing those with access to tax records access to this location data as well.
deleted 5y ago
[deleted]

sneak 5y ago

There is no way to anonymize movement data. Anyone telling you that location data is "de-identified" or "anonymized" is lying to you.

arcticbull 5y ago
Ok but what on earth good is identifiable data to PHAC? Why would PHAC try and de-anonymize this data? What could they possibly do with it? Canadian government entities tend to be well intentioned even if not always the most efficient.
- robbedpeter 5y ago
  When, not if, they have a data breach, those records are trivially deanonymized by malicious third parties. They shouldn't have the data, they don't need it, and storing it long term is completely unnecessary. Collection of private data is only ever appropriate directly from an individual with informed consent, with strict and mutually agreed upon limits on how long it can be stored and the uses to which it can be put. Permanent or long-term data retention should be rare and have intense oversight. Almost everything else should be ephemeral on the level of minutes to hours. Legislation will catch up after this bites us in the ass, and the longer it takes, the worse it's going to be.
  - arcticbull 5y ago
    > They shouldn't have the data, they don't need it, and storing it long term is completely unnecessary. I mean, I completely disagree. If the job of a public health agency isn't to use anonymous data to make informed decisions about public health what on earth is their job?
    - robbedpeter 5y ago
      They don't need location tracking. It's inherently not anonymous.
      - 5y ago