2 ms·

Seems like a scenario where bloom filter[1] could be useful. 1. https://en.wikipedia.org/wiki/Bloom_filter https://en.wikipedia.org/wiki/Bloom_filter

• est31 7y ago
  Bloom filters aren't good for privacy because if there is a hit, you have to upload the id to check it. Which tells the service a) which ID you encountered and b) if it's an ID that was confirmed to be affected, whether you are affected by corona or not, something the system was designed to prevent.
  • mkagenius 7y ago
    > if there is a hit, you have to upload the id to check it. Why would you upload it if you know (almost for sure) there was a hit? We can all live with small false positives I think.
  • jlokier 7y ago
    You don't have to upload the full id. It's enough to upload the bucket that was hit in the Bloom filter to fetch the subset of detailed data that corresponds to the bucket. If the buckets are coarse enough that doesn't reveal much. And if the Bloom filter is too fine-grained for that, fetch a set of buckets instead of one.