Long-form Content: ecash (Transacting with ecash while offline) by gandlaf21 \ stacker news ~bitcoin

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Long-form Content: ecash (Transacting with ecash while offline) by gandlaf21 njump.me/naddr1qq25cjpsdfeyj3z9f3txsejnfezk6mjpwagyyq3qcj6ndx5akfazux7f0vjl4fyx9k0ulf682p437fe03a9ndwqjm0tqxpqqqp65w5zjwnt

213 sats \ 19 comments \ @m0wer 3 Aug bitcoin

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100 sats \ 1 reply \ @ek 3 Aug

But, if you don't have proofs that match the amount, you would need to go online and swap for the needed proofs at the mint.

This also applies to offline receives.

The sender needs to not only know the recipient in advance, but also what denominations they will use. The recipient can’t give you change back.

Still useful, but that’s another important limitation.

34 sats \ 0 replies \ @m0wer OP 4 Aug

For the case of vending machines that's fine. The problem to solve is that the machine can operate without internet, not the customer. So as a customer you can easily get the exact denomination and sign it for the machine online and then the machine does not need internet to verify it.

0 sats \ 3 replies \ @025738dda8 4 Aug

I do not see any difference between sending cashu coins to a receiver with and without any proof.

The sender can send the same coins with different proofs to many senders. What they can verify offline? Nothing related to double spend.

Only the first receiver going online takes the coins. What is the purpose of such proof then?

0 sats \ 2 replies \ @m0wer OP 4 Aug

Ff the sender creates a token locked to your public key (for untrusted transactions), then no, no one else can reclaim it because only you can redeem it with your private key. The trust there is in the mint.

0 sats \ 1 reply \ @025738dda8 4 Aug

But does that mean that the sender must be online to get the token from the mint? Otherwise, how to obtain a token with my pubkey in advance?

0 sats \ 0 replies \ @m0wer OP 4 Aug

Yes. Or at least must have planned it in advance.

Maybe there is a vending machine at the peak of a mountain where neither the machine nor the users will have Internet access. You could plan in advance and get some tokens for that machine.

0 sats \ 0 replies \ @SwapMarket 4 Aug

Stop spreading scammy ideas. Offline wending machine with Lightning has been long solved: https://bitcointalk.org/index.php?topic=5381769.0

0 sats \ 4 replies \ @BlokchainB 3 Aug

If I create a nut and then send it offline can’t I reclaim it first before the receiver?

95 sats \ 3 replies \ @m0wer OP 4 Aug

If I create a nut and then send it offline can’t I reclaim it first before the receiver?

Yes, you can reclaim a nut before the receiver in basic offline transactions - that's the double-spending problem.

However, if the sender creates a token locked to your public key (for untrusted transactions), then no, they cannot reclaim it because only you can redeem it with your private key.

81 sats \ 1 reply \ @SwapMarket 4 Aug

This is subject to sender's mint not cheating. I can run a mint that will issue nuts not backed by anything. So I have no problem locking them to the receiver. The whole idea is based on a delusion. Cashus don't work trustlessly. And trust is not Bitcoin's philosophy.

84 sats \ 0 replies \ @m0wer OP 4 Aug

Cashus don't work trustlessly.

Of course not. The question is if it's the best way of solving the problem of offline payments. The other option currently is banknotes which as you know have other inconveniences.

23 sats \ 0 replies \ @BlokchainB 4 Aug

Ah thanks for the explanation

0 sats \ 6 replies \ @SwapMarket 3 Aug

Offline wending machines are possible with Lightning, if the payer has internet access.
"It cannot contain duplicate proofs (double-spend)" How can an offline receiver verify this? A customized mint can issue Cashu coins not backed by anythig. Cashu are scam.

0 sats \ 5 replies \ @m0wer OP 4 Aug

Sure you have to trust the mint. But you can set a collection of trusted mints beforehand.

0 sats \ 4 replies \ @SwapMarket 4 Aug

I can't, because I don't normally know in advance what mint the payer will use. And I don't want to trust anyone!

0 sats \ 3 replies \ @m0wer OP 4 Aug

There is no way to solve the trust issue offline. Bitcoin solves that hard problem by creating a decentralized trustless ledger. Offline you don't have that possibility.

You should avoid using Cashu in general, because there are better options. What's a better option for this case?

For a vending machine operator, the risk of double spends might be worth it compared to the cost of having an internet connection for the machine. It's all about tradeoffs.

21 sats \ 1 reply \ @SwapMarket 4 Aug

This: https://bitcointalk.org/index.php?topic=5381769.0

0 sats \ 0 replies \ @m0wer OP 4 Aug

Yes that's very nice.

0 sats \ 0 replies \ @SwapMarket 4 Aug

And no, I don't use cashu and fight everyone propagating this scammy idea. No one in their right mind should accept Cashu. It only works for the payers with own mints, they are driving the narrative.