Clear

Digital minting infrastructure for issuer-defined treasury units.

Clear gives communities and institutions the tools to issue their own circulating digital units. An issuer defines what a unit represents, a treasurer authorizes issuance, and the mint creates private bearer Mint Notes that holders can exchange and redeem under the issuer's policy. Built on Cashu, Clear brings treasury authority and holder-held digital value into one minting model.

Why Clear? Organization-issued value Get started View the source

Treasury-defined value, held by the holder

Clear combines an old institutional function with modern cryptography: an organization defines a unit and its obligations, delegates authority to issue it, and recognizes it when it returns for redemption. Holders carry the evidence of their holdings as Mint Notes rather than relying on a balance account at the issuer for every transfer. The name describes the relationship: Credit-Liability Ecash, Authorized and Redeemable.

The core mechanism is mint-enforced unspent bearer proofs. Wallets hold the proofs; the mint maintains the authoritative pending and spent state. A recipient normally swaps received notes for fresh ones to prevent the sender from reusing them. Privacy comes from Cashu's blind signatures, while spendability and redemption still depend on the mint and the responsible institutions.

Payment rails can fund or settle a program. Clear supplies the minting layer: who may issue a unit, what holders possess, and how that unit circulates under its own policy.

That makes Clear useful for communities and corporations that need credits, vouchers, benefits, allowances, or service units. The same model can also serve state-adjacent programs, delegated mints, public-purpose treasury units, or compute-credit systems for software agents. In each case, the important question is not merely how value moves. It is who is authorized to mint the unit, what the unit represents, where it is recognized, and how it is redeemed or retired.

Compare Bitcoin, Ethereum tokens, and Cashu

Cashu, decoupled

Clear is built on Cashu. It preserves Cashu's blind signatures, keysets, bearer proofs, swaps, and spent-proof protection. The fundamental change is at the institutional boundary: Clear decouples those mechanisms from the usual Bitcoin and Lightning settlement loop.

In a conventional Cashu mint, receipt of payment normally authorizes issuance, and returning ecash normally causes a bitcoin or Lightning payout. In Clear, a treasurer acting under issuer policy authorizes issuance, and that policy defines what redemption accomplishes.

Cashu: payment -> bearer ecash -> payment
Clear: policy -> treasury authority -> bearer Mint Notes -> policy consequence

Bitcoin, Lightning, banks, and other rails can still fund or settle a Clear program. They become optional integrations rather than the authority that defines the unit.

Read Cashu, Decoupled

Clear works alongside cash

Clear is not a replacement for Bitcoin, Lightning, or the Cashu mints that use them. In a compatible wallet, sat-denominated funds from those mints form a single Cash Balance: broadly transferable, general-purpose value that can move between people and settle through the Bitcoin and Lightning networks.

Clear adds Clear Balances alongside that cash balance. The plural matters: each balance holds a distinct issuer-defined transferable unit with its own mint, Clear Mint Unit, and policy. A Clear balance may represent food credits, service units, member benefits, event allowances, or other products and in-kind services. It may also represent bounded public-program value or metered compute credits for agents. It can circulate privately between wallets, but it is useful where the relevant issuer and participating providers recognize it; it is not presumed to be cash or universally interchangeable with another Clear balance.

Mint Notes that can circulate

Many organizations already keep internal balances: program credits, community funds, service allowances, guest credits, member credits, event credits, or other limited-purpose value. Clear explores what happens when those balances become portable Mint Notes instead of rows tied to one application account.

Once issued, Clear Mint Notes can be held and transferred like other Cashu ecash. Their technical representation remains a Cashu proof. The difference is at the boundary: no Lightning invoice creates or redeems the notes. A designated treasurer authorizes issuance and accepts Mint Notes for redemption and retirement according to the organization's published policy.

The working lab milestone now carries that model across product boundaries: Clear issues CMUs into a treasury wallet, sends an encrypted transfer to a NIP-05 address, Acorn stores the incoming kind 7379 transfer separately from cash, and Safebox Web lets the recipient accept it into the corresponding spendable Clear Balance.

See the organization-issued value milestone

Issue

A treasurer authorizes a precise amount, and Clear issues the Mint Notes. Clear does not infer authority from a payment invoice.

Circulate

Wallets hold Mint Notes and transfer them directly. Recipients swap received notes for fresh proofs at the mint, which enforces pending and spent state to prevent reuse.

Redeem

The issuer accepts returned Mint Notes under its policy. Clear marks them spent and records retired supply without implying a Lightning payout.

The rule that keeps Clear clear

Every Clear Mint Unit stands alone. Its logical mint, keyset, balance, policy, issuer, and risk remain distinct. Mint Notes from different logical mints or CMUs must never be summed, spent together, or presented as interchangeable. A logical mint may expose an operator-approved mint cluster when its members synchronously coordinate authoritative state.

People can see a friendly name such as Harbour Credits and the abbreviation CMU, pronounced as the letters “C-M-U,” but the canonical protocol unit is bound to the active keyset, for example cmu-00a1b2c3d4e5f6. Keyset rotation creates a new CMU. Any migration must be explicit and must not make unrelated organizational promises appear to be one balance.

Understand Mint Notes and CMU

Authority stays understandable

Clear separates the organization that governs a transferable-unit program, the operator that runs the mint, and the treasurers who authorize routine issuance, redemption, and retirement. Even when one person fills several roles, each role uses a distinct key and leaves different evidence.

See how Clear is governed

A focused Mainstay family product

Clear joins the Mainstay product family as a narrow, independently useful mint service:

Safebox Web gives people approachable record and payment workflows.
Acorn safeguards user-controlled keys, funds, and records.
Grove preserves encrypted blobs.
Spurline preserves and synchronizes Nostr events.
Clear provides issuance, circulation and redemption machinery for Mint Notes denominated in keyset-bound CMUs.
Mainstay is the future unified application.
Lockbox is the hardware-first local appliance.

Clear remains independently deployable. Mainstay and Safebox Web can make its transferable units understandable without hiding who issued them or what each one promises.

Good boundaries, not barriers. Clear remains the authority for its own Mint Notes and proof state; it does not become the wallet, relay, application, or universal issuer. Cashu and Nostr interfaces let the family cooperate without blurring those responsibilities or making separate units interchangeable.

Experimental software

Clear is an early protocol and product experiment. It has not been security reviewed. Do not use it for financial value or critical accounting.