peer to peer ecash transactions in a nutshell
1 - alice sends ecash token to carol
2 - carol sends ecash to bob the mint
3 - bob verifies and checks for double-spending
4 - bob issues a new token to carol
like physical cash, step 1 is instant and works without internet.
Cashu
npub17fzk...9yxv
Open-source Chaumian Ecash protocol for Bitcoin
https://cashu.space/