4 ms·

I noticed they use a Bloom Filter based on ip address to prevent people from voting multiple times. According to the implementation[1] it uses a 256-byte struct

I noticed they use a Bloom Filter based on ip address to prevent people from voting multiple times. According to the implementation[1] it uses a 256-byte structure and limits the total number of votes on a post to 142 [2] (more than that and the false-positive rate > 0.001). This is stored as a sqlite BLOB on the same row as the comment. But if you're limiting votes to ~142 anyways, you can just store the exact ip address of every voter (packed in the BLOB at 4 bytes each) and it would only reach up to double the space (~560). But since the overwhelmingly vast majority of comments won't get nearly that many votes, you'd actually be saving space compared to keeping a bloom filter for each comment. It seems like an overengineered and unnecessary technical complexity. [1]: https://github.com/posativ/isso/blob/master/isso/utils/__init__.py#L39 https://github.com/posativ/isso/blob/master/isso/utils/__ini... [2]: https://github.com/posativ/isso/blob/master/isso/db/comments.py#L186 https://github.com/posativ/isso/blob/master/isso/db/comments...

trurl42 12y ago
I guess the point is to not store ip addresses. Given the focus on allowing anonymous commenting [1] this seems to make sense. [1]: http://posativ.org/isso/docs/#what-s-wrong-with-disqus http://posativ.org/isso/docs/#what-s-wrong-with-disqus
- kevan 12y ago
  In that case you could store a hash of the IP instead.
  - girvo 12y ago
    With a known structure, a hashed IP could be reversed quite easily couldn't it?
  - infogulch 12y ago
    We're limited to ipv4 so even if you hash it you could still test every possible address within a few minutes. You can even do the same with the bloom filter, since there's at worst only a 1/1000 false positive rate (and likely much smaller). The bloom filter isn't designed to provide security, and trying to make (ipv4) IPs private if you're using them as identities is a lost cause.
neurotech1 12y ago
Is there an XKCD[1] comic about over-engineered solutions? I'd be tempted to go with exponential back off for voting. eg. the more votes, the less effect they have on the total score. [1] http://en.wikipedia.org/wiki/Randall_Munroe http://en.wikipedia.org/wiki/Randall_Munroe
deleted 12y ago
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trurl42 12y ago

I guess the point is to not store ip addresses. Given the focus on allowing anonymous commenting [1] this seems to make sense. [1]: http://posativ.org/isso/docs/#what-s-wrong-with-disqus http://posativ.org/isso/docs/#what-s-wrong-with-disqus

kevan 12y ago
In that case you could store a hash of the IP instead.
- girvo 12y ago
  With a known structure, a hashed IP could be reversed quite easily couldn't it?
- infogulch 12y ago
  We're limited to ipv4 so even if you hash it you could still test every possible address within a few minutes. You can even do the same with the bloom filter, since there's at worst only a 1/1000 false positive rate (and likely much smaller). The bloom filter isn't designed to provide security, and trying to make (ipv4) IPs private if you're using them as identities is a lost cause.

neurotech1 12y ago

Is there an XKCD[1] comic about over-engineered solutions? I'd be tempted to go with exponential back off for voting. eg. the more votes, the less effect they have on the total score. [1] http://en.wikipedia.org/wiki/Randall_Munroe http://en.wikipedia.org/wiki/Randall_Munroe

deleted 12y ago

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