Cashu: Ecash 🥜 + ⚡
nuts and bolts
- Open source dev (BoB resident)
- Cashu: ecash protocol
- cashu-ts, nutstash, proxnut...
What is ecash?
What is it good for?
What is ecash?
What is it (not) good for?
What is ecash?
What is ecash?
No Ledger
Distributed Ledger
What is ecash?
No Ledger
Distributed Ledger
Bearer Token
UTXO
What is ecash?
No Ledger
Distributed Ledger
Bearer Token
UTXO
Public transactions
Blinded transactions
What is ecash?
No Ledger
Distributed Ledger
Bearer Token
UTXO
Public transactions
Blinded transactions
Decentralized Blockchain
Centralized verification
What is ecash?
No Ledger
Distributed Ledger
Bearer Token
UTXO
Public transactions
Blinded transactions
Decentralized Blockchain
Centralized verification
Trusted
Trustless
What is ecash?
No Ledger
Distributed Ledger
Bearer Token
UTXO
Public transactions
Blinded transactions
Decentralized Blockchain
Centralized verification
Trusted
Trustless
Ephemeral transactions
Eternal transactions
What is ecash?
No Ledger
Distributed Ledger
Bearer Token
UTXO
Public transactions
Blinded transactions
Decentralized Blockchain
Centralized verification
Trusted
Trustless
Ephemeral transactions
Eternal transactions
|
|
|---|
|
|
|---|
How?
Why?
traditional custodial setup
Alice
Bob
Charlie
Alice
Bob
Charlie
| Sender | Amount | Receiver |
|---|---|---|
| Alice | 10$ | Bob |
| User | Balance |
|---|---|
| Alice | 20$ |
| Bob | 10$ |
| Charlie | 0$ |
Alice
Bob
Charlie
| Sender | Amount | Receiver |
|---|---|---|
| Alice | 10$ | Bob |
| Bob | 5$ | Charlie |
| User | Balance |
|---|---|
| Alice | 20$ |
| Bob | 5$ |
| Charlie | 5$ |
Alice
Bob
Charlie
Authorize
What's wrong?
- Horrible privacy
- Easy to target/censor individuals
- Data honey-pot
ecash custodial setup
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
Only Alice can open
Carbon paper
| Spent secrets |
|---|
Alice
Bob
Charlie
secret
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
Alice
Bob
Charlie
| Spent secrets |
|---|
No Ledger
Bearer Token
Blinded transactions
| Spent secrets |
|---|
No Ledger
Bearer Token
Blinded transactions
| Spent secrets |
|---|
No Ledger
Bearer Token
Blinded transactions
cryptography
What is ecash?
No Ledger
Distributed Ledger
Bearer Token
TXO->UTXO
Public transactions
Blinded transactions
Decentralized Blockchain
Centralized verification
Trusted
Trustless
Ephemeral transactions
Eternal transactions
|
|
|---|
|
|
|---|
How?
Why?
What is ecash?
What is it good for?
What is it good for?
when Privacy is more important than self custody
Convenience for spending amounts while remaining anon
Untraceable
vouchers or other bearer assets
Exchange Protocol for unlinking deposits and withdrawls
Integrated system replacing the account & balance model
Pay-Per-Resource-usage
(e.g. nostr relays)
Why ecash?
Good privacy properties
Efficient (fast & no fees)
Good data safety (no record of transactions)
Why NOT ecash?
Custodial risk
Loss of (bearer) tokens
Not trustless
On-Chain
+ Maximum security
+ Non-Interactive
- Does not scale (for whole planet)
- Expensive and slow
high value transfer/storage
|
|
|---|
Off-Chain
transfer/pay/storage
+ Unilateral exit
+ Instant receiveable
- Big Liquidity lockup required (by ASP)
- VTXO Expiry (online requirement)
+ trustless
+ Instant settlement
- Liquidity constraint (channels)
- Interactive
eCash
micro payments/spending
+ Instant & efficient
+ Private
- Custodial
- Centrally managed
Lift
Channel open
Invoice
