With cashu there's always been a dilemma when sending ecash to someone: did they claim the payment?
Sure a wallet can ask the mint if a certain set of tokens were spent, but that creates a link between the sending and receiving wallet. It's a leak of information that loses you privacy.
A first solution, although maybe impractical, would be to let the mint stream the information about all the spent tokens to clients that request them (through apposite WebSocket endpoints).
So If I am a wallet and I have just sent some e-cash to someone, I can connect to the mint and "listen" until I am satisfied (until I know the e-cash was claimed).
This could put some pressure on the mint and it's not clear to me if it could be used to perform some DoS attack.
A better approach could leverage Nostr!
A mint with that advertises its associated `npub` on the `/v1/info` API endpoint could then regularly publish notes with all the information about freshly spent e-cash.
Clients would just have to query for notes with a `p` tag referencing the `npub` of the mint and look for the e-cash they just sent. Easy.
tragic
npub1u0…yez97
2024-08-18 22:09:57
Author Public Key
npub1u07xw079lxwv24xslarh2eu4v37jtjmwvev0jyk3zjhxg2wnt56seyez97Published at
2024-08-18 22:09:57Event JSON
{
"id": "012783bf4cfdefc23d64e0b41dd864ba97a0bb4548ecb62282f190b12ae365c5",
"pubkey": "e3fc673fc5f99cc554d0ff47756795647d25cb6e6658f912d114ae6429d35d35",
"created_at": 1724018997,
"kind": 1,
"tags": [],
"content": "With cashu there's always been a dilemma when sending ecash to someone: did they claim the payment?\n\nSure a wallet can ask the mint if a certain set of tokens were spent, but that creates a link between the sending and receiving wallet. It's a leak of information that loses you privacy.\n\nA first solution, although maybe impractical, would be to let the mint stream the information about all the spent tokens to clients that request them (through apposite WebSocket endpoints).\nSo If I am a wallet and I have just sent some e-cash to someone, I can connect to the mint and \"listen\" until I am satisfied (until I know the e-cash was claimed).\n\nThis could put some pressure on the mint and it's not clear to me if it could be used to perform some DoS attack.\n\nA better approach could leverage Nostr!\nA mint with that advertises its associated `npub` on the `/v1/info` API endpoint could then regularly publish notes with all the information about freshly spent e-cash.\n\nClients would just have to query for notes with a `p` tag referencing the `npub` of the mint and look for the e-cash they just sent. Easy.\n",
"sig": "9a9bb7e98ec1b9026528a5a2233822471d3d57a1404528f81a3ce93fab421e6f2972e6f3359982713cea3885b1005b610923b358b9b62516de823ca69b1989e6"
}