There are pros and cons to fedimint, and it remains to be seen whether it will be adopted widely within the bitcoin ecosystem.

Nevertheless, it is great to see cutting edge developments like it. I was a little confused when the signet fedimint faucet was announced1 as to exactly how to play with it. Here is a brief step by step guide in case others might find it helpful:

Getting the e-cash sats (fm-sats).

  1. There is a "federation code" which is shown on the signet fedimint faucet page https://faucet.sirion.io/ Copy this code to your clipboard.

  2. Now go to https://fm-app.sirion.io/ and paste the federation code in. This is your e-cash wallet. You have now joined the federation as a user/member, but you have no e-cash sats. You need to get some from the faucet. The faucet will send them to you via the (signet) lightning network.

  3. In your e-cash wallet, click "receive" and put some amount less than 1000 sats in. A signet lightning invoice will be generated for you. The faucet will pay this invoice. Copy it to your clipboard.

  4. Go back to https://faucet.sirion.io/ and paste the invoice in the little textbox next to where it says "invoice to pay," and click "Submit."

  5. Once the invoice is paid, you now have e-cash cats. I think they like to call them fm-sats.

Your e-cash wallet behaves similar to other custodial lightning wallets. This is one of the tradeoffs. Fedimint is a custodial system. However, one of the benefits is that you have more privacy, both from other users of the same mint, and the mint guardians (operators) which operate the mint.

Spending the fm-sats.

You can spend your fm-sats to other users of the same mint, or the mint will send sats on your behalf to pay a signet lightning invoice. The payment is atomic such that you will need to return the same amount of sats back to the mint in order for the lightning invoice to actually be paid.

If you do not have anyone to try out the sending/receiving with, you can generate a signet lightning invoice here https://sigpay.sirion.io/apps/33Au5UDsPWnUL5GVT8q1Yjovw83K/crowdfund and pay it. The sats will then go back into the faucet.

Interoperability and settlement between mints and wallets via lightning, privately!

Exciting to see these types of developments progressing.

Footnotes

  1. https://faucet.sirion.io/

How do I backup my wallet, or is it stored in the browser cookies?

Good question. I do not think the demo has much in the way of backup functionality yet.

Janet want Fed-i coin! 🏛️ 🏛️ 🏛️

Good stuff.

W.r.t. 1 and 2, note that a more natural user workflow is as per the 'Mobile' section on https://faucet.sirion.io/ :

1/ Download fluttermint for Android (or iOS), install apk after download 2/ Run it and scan the QR code on https://faucet.sirion.io/ to join the signet fed

AFAIK fluttermint is just an early bare bones implementation of a customer wallet; but, I've tried it and it seems to do as intended.

Your e-cash wallet behaves similar to other custodial lightning wallets. This is one of the tradeoffs. Fedimint is a custodial system.

Yep you're right to bold this, but it's also fair to point out that it is a federation, not a single custodian; for what that's worth!

e-cash cats.

maybe a new NFT? :)

1/ Download fluttermint for Android (or iOS), install apk after download

This was not possible for me as I was not testing from a mobile phone. But yes, good reminder that there are other ways.

e-cash cats.

maybe a new NFT? :)

:-P

It looks like send/receive is all lightning? Is the actual ecash transfer between mint users supported yet?

Is the actual ecash transfer between mint users supported yet?

Great question! This was unclear to me at first as well, so I asked one of the devs. And the answer is "yes." Transfers between users of the same mint are an identical UX (lightning invoice / payment), it is simply that the lightning settlement happens internally and instantly.

Source: https://github.com/fedimint/fedimint/blob/734f1414298816ef36ae5ca1299049556276ebd6/ln-gateway/src/lib.rs#L184-L190

Another thread which introduces a different mint, cashu: https://stacker.news/items/73445