[bitcoin-dev] Transaction signalling through output address hashing

John Hardy john at seebitcoin.com
Fri Feb 3 00:13:04 UTC 2017

Currently in order to signal support for changes to Bitcoin, only miners are able to do so on the blockchain through BIP9.

One criticism is that the rest of the community is not able to participate in consensus, and other methods of assessing community support are fuzzy and easily manipulated through Sybil.

I was trying to think if there was a way community support could be signaled through transactions without requiring a hard fork, and without increasing the size of transactions at all.

My solution is basically inspired by hashcash and vanity addresses.

The output address of a transaction could basically have the last 4 characters used to signal support for a particular proposal.

To generate an address with 4 consecutive case-insensitive characters should be roughly 34^4 which is just over a million attempts. On typical hardware this should take less than a second.

An example bitcoin address that wanted to support the core roadmap might be:


or to signal support for a big block proposal might be:


Popularity could be measured weighted by fee paid per voting kb.

Issues are that this could lead to transactions been censored by particular miners for political reasons. Also miners might attempt to manipulate the results by stuffing their block with 'fake' transactions. Such attempts could be identified if a large number of voting transactions were not in the mempool.

Despite the limitations, I believe this offers a very accessible way to immediately allow the entire economic community to signal their support within transactions. The only cost is that of a tiny hashing PoW that should tie up a CPU for a barely noticeable amount of time, and could be implemented relatively easily into wallet software.

For its weaknesses, surely it is better than the existing methods we use to assess support from the wider economic community?

While it could just be used for signaling support and giving users a 'voice' on chain, if considered effective it could also be used to activate changes in the future.

Any thoughts welcome.


John Hardy

john at seebitcoin.com
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