Sovereign Engineering / Building block
eCash
Value that travels like a message.
Ecash is digital bearer money. Here we focus on Cashu, an open protocol for Chaumian ecash on Bitcoin. Wallets hold tokens issued by a mint, and those tokens can move through the same channels we use to exchange information.
Privacy through blind signatures
A mint issues tokens using blind signatures, which keep it from directly linking token issuance to later redemption. A recipient exchanges received tokens with the mint for fresh ones, preventing the same tokens from being spent again.
A building block for payments
Cashu tokens can be carried as text, making them useful inside messages and applications. Nutzaps connects ecash payments to Nostr events. TollGate applies bearer payments to network access.
The mint’s role
Tokens are claims on the issuing mint. Holders depend on that mint to redeem them; the privacy mechanism does not remove this trust. This model gives builders a distinct set of tradeoffs to understand when designing a payment flow.
Roots & further growth.
From the cohort archive