  Blockchains add transactions to a distributed shared ledger by arriving at
consensus on sets of transactions contained in blocks. This provides a total
ordering on a set of global transactions. However, total ordering is not enough
to satisfy application semantics under the Byzantine fault model. This is due
to the fact that malicious miners and clients can collaborate to add their own
transactions ahead of correct clients' transactions in order to gain
application level and financial advantages. These attacks fall under the
umbrella of front-running attacks. Therefore, total ordering is not strong
enough to preserve application semantics. In this paper, we propose causality
preserving total order as a solution to this problem. The resulting Blockchains
will be stronger than traditional consensus based blockchains and will provide
enhanced security ensuring correct application semantics in a Byzantine
setting.
