City of Hats
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Open-source security sponsorship

Help fund an independent security audit.

City of Hats publishes its protocol specification and core cryptographic modules under the MIT license. We’re seeking sponsorship to commission an independent security audit and sustain this open-source work.

Your support helps fund audit preparation, independent review, remediation, security testing, and public documentation.

Explore the repository Read the protocol
One-time only USD Secure Stripe checkout

Why an independent audit matters

How do you know your messages really stay private?

It’s a fair question. Saying “your messages are encrypted” is a promise. An independent security audit helps check whether the technology actually delivers on that promise.

A simple example

Imagine sending your home address to a family member. Your message should work like a locked parcel: the service delivers it, but only you and your family member have the keys to read it.

What does an auditor check?

An independent auditor examines the design and code for weaknesses: Is the parcel properly locked? Are the keys protected? Could the reviewed software accidentally expose a readable copy?

“How do I know my messages aren’t being copied to the FBI—or anyone else?”

The important question is whether anyone outside your conversation can obtain a readable copy. Copying an encrypted message should not reveal its contents without the keys.

Checking that protection requires examining how the app handles messages and keys—not simply seeing the word “encrypted” on a website. That is why we want independent specialists to scrutinize our security.

Why we’re seeking your support

We’ve published our protocol specification and core cryptographic modules so others can inspect them. Sponsorship will help us commission a structured independent audit, address findings, and publish the results responsibly.

Independent review is an established practice in secure messaging. Wire describes regular independent audits.

An audit strengthens confidence in the version and components examined. It cannot guarantee future behavior, protect a compromised phone, or prevent a recipient from sharing a message.

Help fund independent scrutiny of our security.
MITLicensed
2Production crypto modules
PublicProtocol specification
OpenFor public inspection

Inspect the work

Security claims should come with evidence.

The cryptographic layer is available for inspection, criticism, and improvement. The repository documents both its design and its limits.

Specification

Protocol architecture

Key exchange flows, Double Ratchet parameters, group sender keys, wire formats, and cryptographic primitives.

Read PROTOCOL.md Production source

Core encryption

Hybrid key exchange, message encryption, ratchets, metadata padding, safety numbers, and local key protection.

Review crypto.ts Production source

Group encryption

Sender-key distribution, HMAC chain ratchet, authenticated encryption, and sender signature verification.

Review groupCrypto.ts

Current funding focus

Our next priority: independent security scrutiny.

We aim to commission an independent assessment of the protocol and cryptographic implementation, including relevant production integration agreed in the audit scope. Sponsorship supports this work, with the audit as our first priority.

We plan to publish the agreed scope, funding updates, and an audit report with remediation progress, allowing time to address sensitive vulnerabilities responsibly. The final scope, auditor, and timetable will be confirmed before the engagement.

  • Independent cryptographic review
  • Security test suites
  • Protocol documentation
  • Vulnerability research and remediation

Designed to address

What the open work covers

  • End-to-end encryption by default
  • Forward secrecy and per-message key evolution
  • Hybrid X25519 + ML-KEM-768 key exchange
  • Identity abstraction through Hat IDs
  • Metadata-conscious message formats

Honest boundaries

What we do not yet claim

  • Protection from compromised endpoints
  • Complete resistance to global traffic analysis
  • Formal mathematical verification
  • A completed independent security audit
  • Open sourcing of proprietary platform systems

Deliberate scope

Open where scrutiny matters. Clear about what remains closed.

Published

Protocol specification, core encryption modules, group cryptography, architecture overview, and MIT license.

Not included

Backend infrastructure, product interfaces, and proprietary intelligence systems.

Community support

Supporters

Your support helps sustain our open-source security work and the planned independent audit.

Sponsorship initiative launched October 7, 2026.

Supporter acknowledgments begin November 1, 2026.

Recognition is your choice

We’re just getting started. From November 1, 2026, public acknowledgments will begin appearing here as contributions are confirmed and supporters approve their display details. One-time contributors are recognized as supporters; ongoing sponsors will be identified separately.

You choose the name or GitHub handle, picture or company logo, and any website link we display. Anonymous support is welcome, and amounts stay private unless you approve publication.

What happens after payment?

After a successful contribution, we’ll contact you privately to arrange optional public recognition. We’ll agree on your display details and get your approval before anything is published.

Questions about recognition?

Call or SMS: +1 473 475 9594 · Send an SMS

Be among our first featured supporters

Company details

City Of Hats Inc.
2967 Dundas Street W, Unit 1689
Toronto, ON M6P 1Z2
Canada

D-U-N-S Number
245274907

COMPANY SPONSORSHIP

Support security. Bring Premium to your whole team.

All employees are included, with no employee seat cap. Choose the sponsorship tier that fits your company.

US$1,000–2,499

12 months of Premium

Premium membership for all your employees. All employee memberships share a 12-month term from the company’s agreed activation date, with no automatic renewal.

US$2,500 OR MORE

Lifetime employee Premium

Lifetime Premium membership for all current and future employees, with no employee seat cap. Your company can continue adding employees without another sponsorship payment.

Both tiers are one-time sponsorships supporting our open-source security work and the planned independent audit. Contact us to arrange employee activation. Public recognition remains optional.

The lifetime benefit lasts for as long as City of Hats offers the Premium service. It covers employee Premium membership; Business / Team administration and Enterprise deployments have separate terms.

Arrange employee Premium access

Call +1 473 475 9594 · Send an SMS

Before you contribute

Clear terms. No fine-print surprises.

Is City of Hats a charity?+

No. City of Hats Inc. is a for-profit Canadian company. Contributions are voluntary and are not charitable donations.

Is my contribution tax deductible?+

No. City of Hats Inc. is not a registered charity or qualified donee and cannot issue an official donation receipt or promise a charitable tax benefit.

What does my contribution purchase?+

Sponsorship supports audit preparation, independent review, remediation, security testing, documentation, and open-source maintenance. Companies sponsoring US$1,000–2,499 receive 12 months of Premium for all employees. Companies sponsoring US$2,500 or more receive lifetime Premium for all current and future employees, with no employee seat cap. Contact us to arrange activation. Other contributions do not include product access. No contribution provides equity, ownership, a financial return, or influence over security findings.

Is this a recurring payment?+

No. Every contribution made through this page is a single, one-time payment. There is no subscription or automatic renewal.

Who processes the payment?+

Stripe processes the payment for City of Hats Inc. City of Hats does not receive your complete card number.

Can I contribute without a City of Hats account?+

Yes. A Hat ID or City of Hats account is not required. Stripe will request the information needed to process your payment and provide a receipt.

What will the independent audit cover?+

The intended assessment covers the protocol and cryptographic implementation, including how relevant app components handle messages and keys. The final scope will be agreed with an independent auditor and published. It will identify the version and components examined; it will not certify every part of the platform.

How will sponsorship funds be used?+

The independent audit is our first funding priority. Sponsorship also supports preparation, remediation, security testing, documentation, and maintenance of the open-source security work. We plan to publish funding and allocation updates.

Is there an audit funding target or completion date?+

A funding target and timetable will be published once the audit scope and quotation are confirmed. Commissioning depends on available funding and auditor availability. Until then, this page makes no promise of a specific completion date.

What happens if funding is insufficient or exceeds the audit cost?+

If funding is insufficient for the intended audit, we will publish an update explaining the next steps and any revised scope or timetable. Funds support the security work described here; any surplus can support remediation and ongoing open-source maintenance. This is not an all-or-nothing campaign.

Can I be publicly acknowledged as a supporter?+

Yes, if you choose. Our sponsorship initiative launched October 7, 2026, and approved supporter acknowledgments will begin appearing from November 1, 2026. After successful payment, we’ll contact you privately to agree on your display name or GitHub handle, picture or company logo, and any website link. We only publish the details you approve. Anonymous support is welcome, and amounts remain private unless separately approved. Contact admin@cityofhats.com with any questions.

What do company sponsors receive?+

Companies sponsoring US$1,000–2,499 receive 12 months of Premium for all employees, sharing one term from the agreed company activation date. Companies sponsoring US$2,500 or more receive lifetime Premium for all current and future employees, with no employee seat cap or additional sponsorship payment required for future hires. Contact admin@cityofhats.com or call/SMS +1 473 475 9594 to arrange activation. Both tiers are one-time payments with no automatic renewal. Lifetime lasts as long as City of Hats offers the Premium service. Business / Team administration and Enterprise deployments have separate terms. Public recognition is optional and requires approval.

Build in the open

Help fund independent security scrutiny.

One-time sponsorship to help fund an independent audit and maintain security work the community can inspect.

Choose a sponsorship amount