On August 5, 2018 9:11:26 PM UTC, Lautaro Dragan via bitcoin-dev
<bitcoin-dev at lists.linuxfoundation.org> wrote:
>Should we actually be using the BIP process to claim a prefix?

I recommend against using an op_return prefix, as they allow for
transaction censorship.

In fact, in our case, where we use an IPFS hash in an op_return, we remove
the IPFS multihash prefix information to post a “bare” SHA256 hash to look
like many other hashes being posted in op_returns, to minimize any ability
for a miner to identify our transaction. The more projects that do this the
better — a form of herd immunity.

Longer term I’m looking for more responsible ways to publish this hash, for
instance have the hash be in the witness script data, so that it can be
easily purged from nodes that do not wish to preserve it and prevent block
size bloat. However, to do so everyone has to do it the same way, ideally
have it look like any other transaction. I’ve not quite seen a solid
proposal for best practices here.

— Christopher Allen