Payjoin - a basic demo

Posted by: Adam Gibson | in Bitcoin, Joinmarket, Testing | 1 year, 6 months ago | 0 comments

I'll shortly be writing a blog post about the idea of "PayJoin", which is a variant of what's sometimes been called "Pay-To-Endpoint" coinjoin, or "p2ep".

If you don't know what "p2ep" is, you're probably better off waiting for the next blogpost.

For now I just wanted to show an example of how it runs in Joinmarket (PR here ; not yet merged but won't be long).

This is a terminal recording with asciinema (which is much more lightweight than a video).

Here, I ran both sender and receiver; each terminal's playback is shown side-by-side at the below link.

Sorry for the copy-paste fumbles in the middle :)

The resulting transaction can be seen here.

As a fun exercise, you could challenge your friends by showing them this transaction and asking them:

"What is the payment amount?"

Having seen the above, you'll know, but I bet they won't be able to figure it out :)

If you do have such a discussion, you'll probably want to note that none of the inputs are bigger than the

biggest output, so there isn't really a reason to be suspicious (for an outsider) that this is anything other

than an ordinary payment; or is there? There's more to discuss for sure :)


Samourai are working on something very similar; this discussion may be interesting too!

Gist discussing some technical issues (see the comments in particular - about UIH1 and UIH2).

Questions? You can reach me on IRC freenode #joinmarket or on mastodon.

If anyone wants to give it a try in the next week or two, feel free to contact me there.

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