Oddbean new post about login | logout On a flight with no Internet. Sent my friend a few Satoshis worth of ecash and possibly set an altitude record doing so. From phone to phone. We're both offline. Try it out on Cashu.me https://image.nostr.build/63c0601a240159e5e84702982c4df80d530b36c1551b9c8f3e25f86cc8280737.jpg
If both of those phones were destroyed then you didn't send the sats. That's not ideal.
I'd say that's a great feature.
Just like cash wouldn’t you say
So where's the money transmitter here? @IRS
Transaction is not settled until the receiver device comes online and contacts the mint. The mint is (illegal) money transmitter.
The mint doesn't transfer anything, it only keeps track of spent tokens.
That's 100% transfering in our book. The transaction would be impossible without the mint.
So ISPs are money transmitters too then since I do online banking through them, and so is google since I use their devices, and so is Firefox, etc.
Just accept that we will interpret the Law however we see fit to get what you want. If you don't like it, you can vOtE hArDeR 🤣
This is the canned reply you should give every time anyone asks you anything
Mile high club
Saw your post the other day and thought 'that looks slick. Wonder what it is or what it does or how it works..?' Got a page that covers that? I've got some bitcoin, got cold storage, got a lightening wallet and got alby setup on nostr... but I still can't really tell what cashu is or what it does and why (compared to just a lightening wallet), but everybody seems excited about it so I want to figure it out.
Revolutionary. I wonder when the first one sent from space will be?
I like this :) It makes the definitions of "mint" and "money transmitter" blurry as fuck!
Hmm. How?
He talked about that here: https://gist.github.com/callebtc/67da3f586ef273df80bf679e464bc3f3#offline-ecash
Thanks
Trust-based. You can do that with on-chain transactions, too. These, too are trust based. In both cases, if the sender decides to undo the payment, he can if he manages to get internet first.
Even with P2PK-locked receiving?
Pretty cool, seems its locked to an address. I studied the base math behind ecash, but haven't read this detail. I wonder how this is achieved.
check it out https://github.com/cashubtc/nuts/blob/main/11.md
Just verified myself. Sender (my laptop) can't clawback the payment because I went out of my way to lock the ecash to the public key of the recipient (my phone). My phone (offline) has a "later" button when receiving offline. It shows up in my offline phone's transaction history when press the receive "later" button. But you can see at the time how much the ecash token is worth and the fact that it is locked to your public key (can't be redeemed by anyone else before you can get to WiFi). Offline instantaneous receiving of sats that are tied to your public key. Amazing. https://image.nostr.build/43a115316cd1d767580d2e1a0fe52ad836c1e4220dd8b7e9efe3fbf7650c83d3.jpg
I test it too. I works except if you lock the ecash to a key the sending phone needs to be online to bring up the barcode?
Yeah, I didn't test that yet. Just testing offline receiving to confirm that the sender couldn't pull back the funds if they got to internet first. (Which they could not. They couldn't claim the token to one of their own accounts since it was locked to the original recipient's public key). I suppose if you knew that every Saturday you would pay the local rancher 100 sats for whatever, that you could make a stack of ready to go QR codes that ONLY that person could cash in. You could print out a stack of QR codes that are like cash except locked to the recipient. (Who can melt them down and spend the sats anywhere they wanted) instead of locked to an establishment like a regular gift card.
True but why would it need an internet connection to lock it
It's physically impossible to prevent the sender from clawing back the funds if the sender gets internet before the recipient does. nostr:nevent1qvzqqqqqqypzq3huhccxt6h34eupz3jeynjgjgek8lel2f4adaea0svyk94a3njdqqsfygz4xk8qcah6a3dj054dpkf3r2gzuyfmr4t4svndluuuhpm60dcs0sxfg
It does not matter really unless the mint punishes the sender for double-spending afterwards but imagine: Alice has a million bucks with a mint, represented as Chaumian tokens. She now clones her device and walks into the desert to meet Bob. Bob shares his public key with Alice. Alice signs the million bucks over to Bob's pubkey. Now if Alice destroys her device and uses her pre-transaction-clone of it, to send the funds to a different receiver before Bob could talk to the mint, what magic other than later punishment for a provable double-spend could there be to prevent this claw-back?
It's basically sending someone the information need to claim funds from the mint. Since both the sender and reciever will have this information, they both can attempt to claim it once Internet is available.
Can the sender revoke it before the recipient has a chance to claim? As in, in an offline transaction. This is very interesting
The new "mile high club" good evening #nostr nostr:nevent1qqswshvwu7qz49h0vth6dym2a528vn3vcvyx6qtn0prhgplfu55dg8qppamhxue69uhk2tnwdaejumr0dspzq5xeflpdskqvdq4swxj59793uvdzqzc9pzatjk3nhmcg2h0js8trqvzqqqqqqy7r0zpn
Cashu vs eNuts. One in the same?
who took the picture/ how many phones do you travel with @calle 👁️⚡👁️ 🤓
AWESOME 😎
Wait, successful send without internet? Via QR/NFC?
Was just trying to replicate this. Looks like you can create the eCash token while offline and then send the token to the other offline cashu.me instance, but it’s not actually redeemed until the instance goes online. Seems reasonable to me. It’s a bit like printing the eCash token string (or QR code) onto paper and then handing someone the paper. You “sent” them eCash, but the token hasn’t been redeemed yet. Is there anything to prevent you from sharing the token multiple times? Then it becomes a race to be the first to redeem it. 🤔
The “rare stats” after the halvening sold for big $. You could be the “mile high sat club.” That was lame, but big thanks for sharing!!!I didn’t know cashu worked offline.
you can thank me with sats https://youtu.be/fvd0tGdjiyE?si=kvVh2ya_eUPILF-o
Thank you with sats??? Sure thing, but why? For sharing a “Trader University now rebranded as Bitcoin University” video? I watch every video that Matthew Kratter posts on the day they come out. Or were you trying to paste your lightening address and posted a video link instead?
Just so we're on the same page: if both parties are offline the ecash can be double-spent. CashuMe allows the sender to delete the token upon sending so that the receiver can have more confidence that it won't be double-spent while they're offline. More: https://gist.github.com/callebtc/67da3f586ef273df80bf679e464bc3f3
Fun-fact in double-spending is, that the receivers don't trust the sender 😑
Yeah, for those cases one person has to be online (using P2PK for example).
ECB promises offline payment without a trace for the digital euro. I am curious how they avoid double spending 😁
Black box hw chips. Manufactured at 3nm scale. Nobodys gonna crack that to double spend 100 euros.
So merchant and customer, both need ECB hardware? That's a stupid plan.
But profitable? 😂
Does this only work if you have the right sizes of ecash "bills" (😂) locally?
Correct! You could choose to overspend if the amount difference is only small, but essentially that's it.
Could it be possible, to use a mint offline? Like people who has ecash already from a mint could communicate with the mint, but noone would have internet? If I understand correctly, when you use a mint, you anyway trust in it. If you do an offline transaction, you have to trust your peer too. If we can have offline mint usage, I still only have to trust the mint. What do I miss?
You trust the mint but you do not need to trust other users. The receiver of a transaction needs to be online in order to refresh the token they received in order to prevent double spending. If there's no Internet, you need to trust the sender (or all previous senders) and the mint.
🔥
@momotahmasbi
همون فدیمنت خودمونه که در موردش ویدئو دادم :) https://youtu.be/ig-iZ1JZ3X0?si=_y4LK95KyLNBhOh3
Sat down or Sat up 😉 😜 nostr:nevent1qqswshvwu7qz49h0vth6dym2a528vn3vcvyx6qtn0prhgplfu55dg8qpz9mhxue69uhkummnw3ezumr49e4k2q3q2rv5lskctqxxs2c8rf2zlzc7xx3qpvzs3w4etgemauy9thegr43sxpqqqqqqz9xs8rc
You can triple spend those sats though until one of you goes back online
An app that facilitates offline transactions is a giant red flag. Scam waiting to happen. Leave offline transactions to people who understand the protocol well enough to do it themselves, don't encourage noobs to trust nonsense
Wild
How is it possible to solve “the double spending problem” offline?
Never mind. This was answered here already: nostr:note1den3q5scfl8rexm8ncd23wgu0dqy5dzlyvzdhxfjt5wlpnqs74msmnk5p4
