On Mon, Jul 20, 2015 at 4:55 PM, Gregory Maxwell <gmaxw...@gmail.com> wrote:
> On Mon, Jul 20, 2015 at 7:10 PM, Gavin Andresen via bitcoin-dev > <bitcoin-dev@lists.linuxfoundation.org> wrote: > > Mitigate a potential CPU exhaustion denial-of-service attack by limiting > > the maximum size of a transaction included in a block. > > This seems like a fairly indirect approach. The resource being watched > for is not the size (otherwise two transactions for 200k would be > strictly worse than one 200k transactions) but the potential of N^2 > costs related to repeated hashing in checksig; which this ignores. > Yes. The tradeoff is implementation complexity: it is trivial to check transaction size, not as trivial to count signature operations, because number-of-bytes-in-transaction doesn't require any context. But I would REALLY hate myself if in ten years a future version of me was struggling to get consensus to move away from some stupid 100,000 byte transaction size limit I imposed to mitigate a potential DoS attack. So I agree, a limit on sigops is the right way to go. And if that is being changed, might as well accurately count exactly how many sigops a transaction actually requires to be validated... -- -- Gavin Andresen
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