Count unique IPs in an anonymous way
Currently, pyobfsproxy (and obfsproxy) keep a list of IPs (or IP hashes) in memory to count connected unique IPs.
Velope suggested that we should find a more privacy-preserving way of counting unique IPs, and he is right.
Aaron suggested to look into https://git.eff.org/?p=cryptolog.git and nick suggested to "use a bloom filter; count bits; get a probabilistic answer".