LibraryPrivacy2023Design paperCorpus record
Cashu: Chaumian ecash notes on top of Bitcoin custodians
Cashu. Cashu.
Cashu publishes Chaumian ecash: a mint blinds and signs notes, and a bearer proof spends them. The mint is a custodian. The cryptography hides which note is which, not the fact of custody.
A reading of the project's public design document. Not a copy, not a benchmark, and not an offer.
Cashu publishes Chaumian ecash: a mint blinds and signs notes, and a bearer proof spends them. The mint is a custodian. The cryptography hides which note is which, not the fact of custody.
- Evidence
- Primary paper
- Re-measured
- No
- Assumptions
- 3
- Records linked
- 5
01 Claim ledger
What the paper is allowed to say
Each row is a sentence already in the study. The status is the same on every row: a model claim, not a live measurement.
Claim 01 · Paper model
The defect
Ecash that forgets to say the mint can refuse or vanish has described a privacy feature and hidden the credit risk.
Claim 02 · Paper model
The proposal
Cashu publishes Chaumian ecash: a mint blinds and signs notes, and a bearer proof spends them. The mint is a custodian. The cryptography hides which note is which, not the fact of custody.
Claim 03 · Paper model
The mechanism
A user blinds a message. The mint signs it without seeing the serial. Unblinding gives the user a note the mint will recognise later.
Claim 04 · Paper model
The bound
This note does not claim a mint is solvent.
02 Three cuts
Observation, model, falsifier
A desk does not stop at the summary. Each claim is cut three ways, using only this study's own assumptions and checks. Nothing here is a new figure.
01 The defect
Observation
What the study says
Ecash that forgets to say the mint can refuse or vanish has described a privacy feature and hidden the credit risk.
Model
What has to hold
You are reading the Cashu NUTs. A particular mint's reputation is not the protocol.
Falsifier
What would retire it
Who can inflate notes: the mint, by signing?
02 The proposal
Observation
What the study says
Cashu publishes Chaumian ecash: a mint blinds and signs notes, and a bearer proof spends them. The mint is a custodian. The cryptography hides which note is which, not the fact of custody.
Model
What has to hold
You are reading the Cashu NUTs. A particular mint's reputation is not the protocol.
Falsifier
What would retire it
Who can inflate notes: the mint, by signing?
03 The mechanism
Observation
What the study says
A user blinds a message. The mint signs it without seeing the serial. Unblinding gives the user a note the mint will recognise later.
Model
What has to hold
No price, supply, yield, or adoption figure is added by this desk.
Falsifier
What would retire it
What happens to notes if the mint disappears?
04 The bound
Observation
What the study says
This note does not claim a mint is solvent.
Model
What has to hold
You are reading the Cashu NUTs. A particular mint's reputation is not the protocol.
Falsifier
What would retire it
Who can inflate notes: the mint, by signing?
03 Sequence
One action, as an operating tape
04 Load-bearing
The argument, and where a pitch drops it
What the name has to mean
The cut
Cashu publishes Chaumian ecash: a mint blinds and signs notes, and a bearer proof spends them. The mint is a custodian. The cryptography hides which note is which, not the fact of custody.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
A later client, parameter or reward formula is a different object from this paragraph.
What actually moves
The cut
Double spending is prevented by the mint's ledger of spent serials, not by Bitcoin consensus.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
A later client, parameter or reward formula is a different object from this paragraph.
What a later deployment may change
The cut
The NUTs are the specification documents. A wallet is not the NUT.
Why it carries weight
If this cut is skipped, the paper's name is being used without the mechanism that makes the name mean anything.
Where it is dropped
A later client, parameter or reward formula is a different object from this paragraph.
05 Register
What has to be true
Model · Not re-measured
You are reading the Cashu NUTs. A particular mint's reputation is not the protocol.
Model · Not re-measured
The document is the one at the source URL. A marketing page with the same brand is not this text.
Model · Not re-measured
No price, supply, yield, or adoption figure is added by this desk.
06 Divergence
What happened after the paper
This is not Fedimint. The mint model differs.
A later client, parameter set, or reward formula is a different object. Cite this paper for the mechanism. Cite a primary release for the network. This desk has not re-run the proof.
07 Pre-mortem
What to check before you use the idea
- 0 of 3 marked on this browser. A mark is a reading note, not a pass, a rating, or a recommendation.
08 Anatomy
The paper, in the order a builder needs
The problem it names
Ecash that forgets to say the mint can refuse or vanish has described a privacy feature and hidden the credit risk.
What the design proposes
How the mechanism is specified
What this page does not treat as proven
- This note does not claim a mint is solvent.
- Privacy is against other users of the mint, within the blind-signature assumption. It is not privacy against a mint that logs network traffic outside the protocol.
- This is not Fedimint. The mint model differs.
Why the desk still reads it
Cashu publishes Chaumian ecash: a mint blinds and signs notes, and a bearer proof spends them. The mint is a custodian. The cryptography hides which note is which, not the fact of custody.
09 Lexicon
Terms, opened into the record
- Blind signature
- A signature on a message the signer has not seen in the clear.
- Mint
- The custodian that signs notes. Custody is the credit assumption.
10 Repository
Every linked record on this page
Underlined words open a page that already exists: a concept, a protocol profile, a failure record, or another paper. If a word is not underlined, this desk does not have a record for it.
This is Blockchain Lab's reading of a public design paper. It is not the paper, not a copy of it, and not an offer of tokens, equity, custody or a partnership. Later network behaviour can diverge from the text. Nothing here is investment, legal or technical advice.
Research status: Design paper. Last reviewed: 1 October 2026. This is a reading of a public paper, not investment, legal or security advice.