Charge exponential gas for (unbounded) number of log topics

[ryscheng-bot]

@nhynes commented on Apr 24, 2019, 7:02 PM UTC:

The false positive rate of a bloom filter grows inverse exponentially with the number of elements (topics) included. Ethereum charges linear gas per topic, which could lead to DoS attacks if the number of topics weren't limited to four (which is, itself, an arbitrary restriction). The proposal is to allow an unlimited number of topics by charging proportionally to the increase in collision probability (w.r.t. the expected collision probability for the current block--possibly based on historical Ethereum data).

This issue was moved by willscott from oasislabs/private-issues#468.