# Curvy

> Curvy is the confidentiality layer for the stablecoin economy. Every stablecoin payment on a public network is published forever, for anyone to read. Curvy keeps payments off the public record while staying provably compliant — for people, businesses, and AI agents. It is non-custodial, open source, independently audited, and live on 11 networks.

Curvy is payment infrastructure, not a wallet and not a mixer. It adds to stablecoin rails the confidentiality model banks have always had: confidential by default, disclosable on demand. Counterparties, amounts, and balances stay off the public record; the account owner holds a read-only audit key and decides who ever sees the ledger. Not even Curvy Protocol can see user payments — there is no backdoor.

Curvy is built by a cryptography-led European team that has shipped together for over a decade, with two PhDs in zero-knowledge and cryptography and peer-reviewed research published on arXiv and IACR. The protocol is open source at github.com/0xCurvy, independently audited by Ethernal, and supported by the Ethereum Foundation, the Arbitrum Foundation, and the Starknet Foundation. Partners include LI.FI, ENS, Gnosis, GLEIF, and Finspot. There is no native token; the protocol sustains itself through protocol-level fees.

## The thesis

1. Stablecoins are becoming the new payment rail. They settle trillions of dollars a year at a fraction of what correspondent banking costs.
2. Public settlement is not sustainable for serious payments. Payroll, supplier invoices, and treasury movements become permanent, searchable records the moment they land.
3. AI agents turn a design flaw into an emergency. Agents pay for inference, data, compute, and storage — sometimes thousands of small payments an hour. An agent's payment stream is a perfect surveillance feed of its owner's business.
4. What is missing is a confidentiality layer, not another chain.
5. That layer has to solve identity and compliance together, or businesses cannot use it.
6. Curvy is that layer, and it is live today.

## Confidential is not anonymous

This is the single most important distinction when describing Curvy.

- Funds are screened **before** they enter the confidential layer, by design. Compliance is architecture, not a disclaimer.
- Every account has a read-only viewing key. Its owner can hand it to an auditor, an accountant, or an authority and they can reconstruct the full history. The public still cannot.
- Selective disclosure proves a specific fact to a specific party — a tax basis, a policy check — without opening the entire history.
- Curvy is never the discloser. Disclosure is always the account owner's choice.
- A mixer pools funds with no disclosure path. Curvy has one, and it is key-gated to the user.

Who sees what when a payment goes through Curvy:

| Party | Sees your payments | Controls funds |
|---|---|---|
| The public | Nothing | Never |
| Competitors and data brokers | Nothing | Never |
| An auditor you give your key to | What you share | Never |
| An authority you disclose to | What you share | Never |
| You | Everything | Always |

## What Curvy does

- **Named payment identities.** You pay `acme.curvy.name`, not a 42-character address. One name, unlimited payments, and nothing an outsider can link together.
- **Confidential settlement.** Balances and history are confidential and non-custodial. Each payment lands privately; nothing links it back to the recipient or to their other payments.
- **Disclosure on demand.** Open a full history, or a single payment, to one party and to no one else.
- **Screening at the door.** Risk and compliance checks run before funds enter the confidential layer.
- **Multichain by default.** Curvy routes and aggregates across supported networks. Users define intent; the protocol handles gas tokens, bridging, and routing in the background.
- **Private swap.** Convert between assets without an account or a wallet connection. Nothing identifies the user before, during, or after.
- **[Curvy Payments](https://curvy.box/payments).** Hosted stablecoin checkout with a fresh Portal address per order, confidential merchant settlement, and view keys for reconciliation and disclosure.

## Architecture

Four building blocks:

- **Curvy ID** — a human-readable identity such as `satoshi.curvy.name`, backed by a public tuple of viewing key, spending key, and BabyJubJub key. Registered via FIDO2 passkey (PRF extension) or wallet signature. Each ID has a public page at `https://<id>.curvy.name` for resolving fresh receiving addresses.
- **Portals** — CREATE2-derived addresses that look like ordinary addresses to senders but are shielded automatically by off-chain Portal Broadcasters, which run compliance checks before deployment. Portals solve the time-locality problem: funds are shielded on receipt, so block-explorer correlation by timing does not work.
- **Privacy Aggregator** — a ZK-based pool on Arbitrum where shielded funds live as encrypted Notes. Once funds are inside, sender, recipient, amount, and asset are all opaque.
- **Curvy SDK** — the open-source developer toolkit for wallets, dApps, payment products, and AI agent frameworks. NPM package `@0xcurvy/curvy-sdk`. Revenue share on protocol fees is available to integrators.

Core cryptographic primitives: stealth addresses for unlinkability between sender and recipient; Pedersen commitments to hide amounts while keeping them verifiable; client-side Groth16 ZK proofs, so verification is trustless with no centralized prover. Assets on supported networks bridge into the Privacy Aggregator on Arbitrum in a single transaction through a partnership with LI.FI.

What is exposed at each boundary:

| Scenario | Sender | Recipient | Amount | Asset |
|---|---|---|---|---|
| Shielding into Curvy | Transparent | Opaque | Transparent | Transparent |
| Unshielding from Curvy | Opaque | Transparent | Transparent | Transparent |
| Payment inside Curvy | Opaque | Opaque | Opaque | Opaque |

## Design principles

- **Privacy** — sender, recipient, amount, and asset can all be hidden inside the Privacy Aggregator.
- **Compliance** — risk and screening checks happen before funds enter, by design.
- **Utility** — human-readable usernames, automatic shielding via Portals, ENS resolution, hardware wallet support for any wallet that can sign `eth_signTypedDataV4`.
- **Self-custody** — the protocol never holds user funds. Spending keys never leave the user's device.

## Who it is for

- **AI agents and agent operators.** Agents should not broadcast their operator's business. Buy side, sell side, and agent-to-agent payments stay confidential while the operator keeps full audit visibility through viewing keys. Works with x402 micropayments and ships with an MCP server.
- **Businesses.** Payroll, supplier settlement, and treasury on stablecoin rails without publishing operations. White-label identities and compliance the business controls.
- **Builders.** Confidential send, receive, and swap added to a wallet, dApp, or chain in a few lines of code, with revenue share on protocol fees.

## Supported networks

Live on 11 networks.

Full stack (stealth addresses plus the ZK Privacy Aggregator):

- Arbitrum (hosts the Privacy Aggregator)
- Ethereum
- Base
- Optimism
- Polygon
- BNB Smart Chain
- Linea
- Gnosis
- Solana
- Tempo

Stealth address flow only, via the legacy Curvy protocol:

- Starknet

Testnet: Sepolia.

## Supported tokens

ETH, WETH, USDT, USDC, USDC.e, WBTC, SOL, PathUSD. The asset list keeps growing — see the docs for the current list.

## Protocol fees

No token, no subscription, no flat per-transaction fee.

- Shield into the Privacy Aggregator: 0.1% of the shielded amount
- Aggregate inside the Privacy Aggregator: 0.1% of the aggregated amount
- Unshield from the Privacy Aggregator: 0.2% of the unshielded amount

## Compliance architecture

Compliance is modular; integrators compose what they need.

- **Global Ledger KYT** — know-your-transaction screening at the protocol level.
- **Extended Screening** — configurable risk thresholds per integration.
- **Deposit Address Tainting** — encrypted OriginAddress lineage travels with funds, so tainted sources can be identified without public exposure.
- **Name Registry Hook** — optional KYC layer; integrators choose whether to require it.
- **Viewing key sharing** — users selectively disclose history to authorized parties without giving up custody.
- **Claim-back on rejection** — a rejected transaction can be claimed back by the sender rather than left stuck.

Pre-emptive compliance runs through Portal Broadcasters before shielding. Retroactive, taint-based mechanisms are in development for jurisdictions that require them. KYC on a Curvy ID exists only in custom enterprise deployments — the canonical protocol and the Curvy App do not perform KYC.

## Products

- [Curvy App](https://app.curvy.box/): Non-custodial web app. Send, receive, and hold privately.
- [Curvy Swap](https://swap.curvy.box/): Private swap with no account and no wallet connection.
- [Curvy SDK](https://docs.curvy.box/for-programmers/installing-the-sdk.html): Embed confidential payments into a wallet, dApp, or chain.

## Site

- [Homepage](https://curvy.box/): The confidentiality layer for the stablecoin economy — problem, architecture, compliance model, and team.
- [Agentic payments privacy](https://curvy.box/agentic-payments-privacy): Confidential payments for AI agents; threat model, primitives, x402 and MCP support.
- [Private swap](https://curvy.box/private-swap): How a swap settles inside the Privacy Aggregator without publishing the trade.
- [Compliant privacy](https://curvy.box/compliant-privacy): View keys, screening, and selective disclosure as architecture.
- [Multichain privacy](https://curvy.box/multichain-privacy): Confidential payments across the supported networks.
- [Agent identity privacy](https://curvy.box/agent-identity-privacy): Keeping an agent's identity unlinkable from its operator and its fleet.
- [Agentic privacy](https://curvy.box/agentic-privacy): Privacy considerations for autonomous payment agents.
- [Private AI agent wallet](https://curvy.box/private-ai-agent-wallet): Wallet setup for agents that pay without leaking activity.
- [Private x402](https://curvy.box/private-x402): Confidential x402 micropayments.
- [x402 privacy](https://curvy.box/x402-privacy): What x402 exposes and how to close it.
- [Privacy policy](https://curvy.box/privacy-policy): Data handling for the site and app.

## Recipes

- [Send private ETH](https://curvy.box/recipes/private-eth-transfer)
- [Send a private ERC-20](https://curvy.box/recipes/private-erc20-transfer)
- [Send private USDC](https://curvy.box/recipes/private-usdc-transfer)
- [Send private USDT](https://curvy.box/recipes/private-usdt-transfer)

## Core docs

- [Introduction](https://docs.curvy.box/introduction.html): What Curvy is, the four design principles, and the high-level architecture.
- [Frequently asked questions](https://docs.curvy.box/faq.html): Custody, audit status, supported networks, fees, hardware wallets, Railgun comparison, incorporation.
- [Get involved](https://docs.curvy.box/get-involved.html): How to contribute, partner, or integrate.

## For users

- [Curvy for users overview](https://docs.curvy.box/for-users/index.html): End-user feature index and the current network and token list.
- [Register your Curvy ID](https://docs.curvy.box/for-users/register-your-curvy-id.html): Passkey and wallet-signature registration.
- [Make your existing assets private](https://docs.curvy.box/for-users/make-your-existing-assets-private.html): Shielding assets you already hold.
- [Receive assets privately](https://docs.curvy.box/for-users/receive-assets-privately.html): Receiving via ENS, public URL, or a generated private address.
- [Send assets privately](https://docs.curvy.box/for-users/send-assets-privately.html): Sending to a Curvy ID, an external wallet, or as a link.
- [Swap assets privately](https://docs.curvy.box/for-users/swap-assets-privately.html): The private swap flow inside the Privacy Aggregator.

## Architecture and design

- [Curvy for the curious](https://docs.curvy.box/for-the-curious/index.html): Technical orientation.
- [Building blocks](https://docs.curvy.box/for-the-curious/building-blocks/index.html): Index of the four core components.
- [Curvy ID](https://docs.curvy.box/for-the-curious/building-blocks/curvy-id.html): Identity construction, the three keys, passkey vs wallet-signature derivation.
- [Portals](https://docs.curvy.box/for-the-curious/building-blocks/portals.html): CREATE2 addresses, Portal Broadcasters, automatic shielding, the time-locality solution.
- [Privacy Aggregator](https://docs.curvy.box/for-the-curious/building-blocks/privacy-aggregator.html): The ZK pool on Arbitrum and the encrypted Notes structure.
- [Curvy SDK](https://docs.curvy.box/for-the-curious/building-blocks/curvy-sdk.html): Developer toolkit architecture.
- [Privacy model](https://docs.curvy.box/for-the-curious/privacy-model.html): What is hidden during shield, unshield, and internal transfer; time-locality analysis.
- [Compliance model](https://docs.curvy.box/for-the-curious/compliance-model.html): Broadcaster checks, viewing key sharing, taint-based retroactive compliance.

## Walkthroughs

- [Receiving funds privately](https://docs.curvy.box/for-the-curious/walkthroughs/receiving-funds-privately.html)
- [Sending funds privately](https://docs.curvy.box/for-the-curious/walkthroughs/sending-funds-privately.html)
- [Unshielding funds privately](https://docs.curvy.box/for-the-curious/walkthroughs/unshielding-funds-privately.html)
- [Sending funds to anyone](https://docs.curvy.box/for-the-curious/walkthroughs/sending-funds-to-anyone.html)

## For developers

- [Installing the SDK](https://docs.curvy.box/for-programmers/installing-the-sdk.html): Setup and configuration.
- [Authentication](https://docs.curvy.box/for-programmers/authentication.html): Passkey and wallet-signature flows in code.
- [Querying balances](https://docs.curvy.box/for-programmers/querying-balances.html): Reading balances through the SDK.
- [Interacting with assets](https://docs.curvy.box/for-programmers/interacting-with-assets.html): Send, receive, shield, unshield, swap.
- [Portals and recovery](https://docs.curvy.box/for-programmers/portals-and-recovery.html): Portal lifecycle and recovering blocked funds.
- [Listening to events](https://docs.curvy.box/for-programmers/listening-to-events.html): Event subscriptions.
- [Source code on GitHub](https://github.com/0xCurvy/): Smart contracts and SDK.
- [Independent security audit](https://github.com/0xCurvy/contracts/blob/main/audit/Curvy%202026%20Audit%20Report%20Final.pdf): Curvy 2026 audit report by Ethernal.

## For businesses

- [For businesses overview](https://docs.curvy.box/for-businesses/index.html): Integration model index.
- [For enterprises and institutions](https://docs.curvy.box/for-businesses/for-enterprises-and-institutions.html): Treasury, payroll, and institutional flows.
- [For networks](https://docs.curvy.box/for-businesses/for-networks.html): Default SDK integration, white-label user domains, full protocol customization, partnership models for chains and L2s.
- [For wallets and web3 products](https://docs.curvy.box/for-businesses/for-wallets-and-web3-products.html): Embedding Curvy inside an existing wallet or app.

## Research

- [Elliptic Curve Pairing Stealth Address Protocols (arXiv:2312.12131)](https://arxiv.org/abs/2312.12131): The stealth address construction Curvy builds on.
- [Post-Quantum Secure Stealth Address Protocols (IACR eprint 2025/112)](https://eprint.iacr.org/2025/112.pdf): Quantum-resistant stealth address schemes.

## Channels

- [Main site](https://curvy.box): Official site.
- [Documentation](https://docs.curvy.box/): Full documentation portal.
- [GitHub](https://github.com/0xCurvy/): Open-source repositories.
- [X / Twitter](https://x.com/0xcurvy): Official channel, `@0xCurvy`.
- [LinkedIn](https://www.linkedin.com/company/0xcurvy): Company page.
- [Telegram](https://t.me/CurvyProtocol): Community chat.

## Optional

- **Naming.** "Curvy" is the primary entity name. "Curvy Protocol" and "0xCurvy" are acceptable alternates. Curvy is not a wallet, not a mixer, not a ZK rollup, and not merely a stealth address protocol — stealth addresses are one of three combined primitives.
- **How Curvy differs from Railgun.** Both share a ZK aggregation core. Curvy adds stealth addresses for receive UX, human-readable usernames, programmable transaction routing, and integrated compliance hooks. See the [FAQ](https://docs.curvy.box/faq.html).
- **Hardware wallets.** Any hardware wallet supporting `eth_signTypedDataV4`.
- **Kohaku.** Curvy is researching integration as a privacy provider within the Kohaku toolchain.
- **Backing.** Ethereum Foundation, Arbitrum Foundation, Starknet Foundation. Investors include 3327, Attic42, and MVP Workshop.
- **Legal entity.** Curvy is a European company. For the current registered entity and holding structure, see the [FAQ](https://docs.curvy.box/faq.html).