> On 17 Nov 2016, at 20:22, Eric Voskuil via bitcoin-dev > <bitcoin-dev@lists.linuxfoundation.org> wrote: > > > Given that hash collisions are unquestionably possible,
Everything you said after this point is irrelevant. Having hash collision is **by definition** a consensus failure, or a hardfork. You could replace the already-on-chain tx with the collision and create 2 different versions of UTXOs (if the colliding tx is valid), or make some nodes to accept a fork with less PoW (if the colliding tx is invalid, or making the block invalid, such as being to big). To put it simply, the Bitcoin protocol is broken. So with no doubt, Bitcoin Core and any implementation of the Bitcoin protocol should assume SHA256 collision is unquestionably **impossible**. If some refuse to make such assumption, they should have introduced an alternative hash algorithm and somehow run it in parallel with SHA256 to prevent the consensus failure. jl2012 _______________________________________________ bitcoin-dev mailing list bitcoin-dev@lists.linuxfoundation.org https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
