Isso – Open Source Alternative to Disqus

Re:Isso – Open Source Alternative to Disqus by infogulch on Tuesday January 27, 2015 @02:06PM (#8954989)

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/__ini...

[2]: https://github.com/posativ/isso/blob/master/isso/db/comments...

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Re:Isso – Open Source Alternative to Disqus by trurl42 on Tuesday January 27, 2015 @03:59PM (#8955830)

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

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Re:Isso – Open Source Alternative to Disqus by kevan on Tuesday January 27, 2015 @06:23PM (#8956883)

In that case you could store a hash of the IP instead.

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Re:Isso – Open Source Alternative to Disqus by infogulch on Tuesday January 27, 2015 @07:26PM (#8957181)

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.

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Re:Isso – Open Source Alternative to Disqus by girvo on Tuesday January 27, 2015 @07:13PM (#8957124)

With a known structure, a hashed IP could be reversed quite easily couldn't it?

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Re:Isso – Open Source Alternative to Disqus by neurotech1 on Tuesday January 27, 2015 @06:31PM (#8956921)

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

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