🐱 FatCat Protocol™

The Universal 12-Button Interface Standard

One protocol serving everyone: from hobbyist DIY wallets to Central Banks moving billions. Standardized, self-programmable, hardware-independent Bitcoin and IoT operations using just 12 buttons (0-9, *, #).

📡 What is FatCat Protocol?

FatCat Protocol™ defines a universal 12-button interface standard (0-9, *, #) that enables any device—from $20 DIY hardware wallets to billion-dollar institutional custody systems—to perform Bitcoin operations and IoT functions through a standardized keypad interface.

Core Vision: Self-programming devices where manufacturers, operators, and users can program IoT devices, ATMs, industrial machines, and institutional ceremony systems directly at the keypad without external computers.

🎯 Key Breakthrough: Standardization

Just as USB standardized device connectivity, FatCat Protocol™ standardizes terminal interfaces. This enables:

  • Hardware Independence - Any manufacturer can build compatible devices
  • Self-Programming - Configure devices at the keypad, no PC required
  • Universal Training - Learn once, operate any FatCat device
  • Ceremony Interoperability - Multi-institution protocols work seamlessly
  • Supply Chain Resilience - No vendor lock-in, competitive ecosystem
Standard Input: 0-9 (numeric), * (confirm/yes), # (cancel/no)
Standard Output: 2-4 line LCD display
Standard Operations: PIN, BIP39 recovery, PSBT signing, multi-sig coordination

🌍 Industries & Scales Served

FatCat Protocol™ is deliberately designed to serve all scales of Bitcoin operations—from individual hobbyists to sovereign nations—using the same universal standard.

🔧 DIY Hobbyists

Hardware Wallet: Build your own $20 self-custody device with Raspberry Pi Pico and 12-button keypad. Generate seeds, sign transactions, full Bitcoin operations.

🏪 Small Businesses

Vending Machines: IoT payment terminals accepting Bitcoin. Program prices, dispense products, no internet required for basic operations.

🏢 Commercial Enterprises

Bitcoin ATMs: Self-service kiosks for public Bitcoin access. KYC workflows, transaction limits, regulatory compliance—all programmed at the keypad.

🔐 Security & Auth

2FA Systems: Passwordless authentication using 12-button challenge-response. Enterprise login, facility access, secure terminals.

💱 Cryptocurrency Exchanges

OneWay™ Custody: Cold storage systems with one-way deposit architecture. Program signing ceremonies, withdrawal policies, compliance rules directly at secure terminals.

🏛️ Central Banks & Nation States

Ceremony™: Multi-sig authorization for billion-dollar reserve movements. 3-of-5 threshold signatures across geographic locations with regulatory observers and audit trails.

💰 Sovereign Wealth Funds

Strategic Reserves: Long-term Bitcoin holdings with multi-decade time locks, institutional governance, and formal authorization ceremonies.

🌐 Regulatory Bodies

Oversight & Compliance: IMF, BIS, SEC observers can audit ceremony protocols. Standardized interfaces enable regulatory oversight without compromising operational security.

🚀 Breakthrough Applications

Each demonstration showcases how the FatCat Protocol™ standard enables previously impossible or impractical use cases:

🔐 Hardware Wallet - Personal Sovereignty

Breakthrough: $20 DIY device with full Bitcoin functionality. No vendor trust required—build it yourself, verify the open-source code, control your wealth.

Target Users: Privacy advocates, self-custody enthusiasts, developing nations without banking access, anyone wanting to escape financial surveillance.

🏧 Bitcoin ATM - Public Access

Breakthrough: Self-service Bitcoin kiosks programmable at the keypad. Operators can adjust limits, fees, KYC rules without manufacturer support.

Target Users: Bitcoin ATM operators, convenience stores, travel hubs, underbanked communities needing cash-to-Bitcoin access.

🎰 Vending Machine - IoT Payments

Breakthrough: Lightning Network payments for everyday commerce. Instant settlement, micro-payments, programmable pricing—all without internet dependency for core operations.

Target Users: Vending operators, micro-merchants, developing markets, lightning-native commerce.

🔑 2FA Auth System - Passwordless Security

Breakthrough: Hardware-based authentication using challenge-response. Eliminates phishing, credential theft, password reuse—works offline.

Target Users: Enterprises needing high-security login, facility access control, secure terminal operators, military/government applications.

🏦 OneWay™ Custody - Exchange Security

Breakthrough: Air-gapped cold storage with one-way deposit flow. Deposits never touch internet-connected systems. Withdrawal ceremonies prevent insider theft.

Target Users: Cryptocurrency exchanges, custodians, institutional treasury teams, anyone holding customer Bitcoin needing maximum security.

🏛️ Ceremony™ - Sovereign Multi-Sig

Breakthrough: Formal multi-sig authorization ceremonies for nation-state Bitcoin operations. 3-of-5 threshold across geographic locations (NY Fed, ECB, BoJ, SNB, MAS). 4-hour signing window, regulatory observers, complete audit trails.

Target Users: Central Banks, Sovereign Wealth Funds, national treasuries, strategic Bitcoin reserve management, trillion-dollar institutional operations.

Common Thread: All these breakthrough applications are enabled by standardization. Without a universal 12-button protocol, each manufacturer would create proprietary interfaces, preventing interoperability, multi-institution ceremonies, and competitive hardware ecosystems.

⚙️ Technical Architecture

Why 12 Buttons?

The 0-9, *, # keypad is:

  • Universal: Globally recognized from phones, ATMs, calculators
  • Manufacturing: Cheap, durable, available everywhere
  • Tactile: Works with gloves, in darkness, for accessibility
  • Sufficient: Supports BIP39 wordlist entry, hex input, menu navigation
  • Constraint-Driven: Forces good UX design—no cluttered interfaces

Self-Programming Architecture

FatCat devices can be programmed at the keypad without external computers:

  • Configuration Menus: Navigate settings with 0-9, confirm with *, cancel with #
  • Seed Generation: Device generates BIP39 seeds, user backs up on paper
  • Seed Recovery: Enter 12/24 word seeds using numeric keypad mapping
  • Policy Programming: Set transaction limits, time locks, multi-sig thresholds
  • Ceremony Coordination: Configure multi-party signing without external orchestration

Security Model

  • Air-Gap Compatible: Devices can operate completely offline
  • No Trusted Display: Critical data verified through physical keypad entry
  • Secure Element Support: Standard interface works with hardware security modules
  • Ceremony Attestation: Multi-sig protocols with cryptographic proof of participation

Interoperability

Because FatCat Protocol™ is a standard, not a product:

  • Any manufacturer can build FatCat-compatible devices
  • Multi-institution ceremonies work across different hardware vendors
  • Users trained on one device can operate any FatCat device
  • Competitive market drives better hardware, lower prices, more innovation
  • No single point of failure in supply chain

⚠️ Known Limitations & v2.0 Roadmap

FatCat Protocol™ v1.0 is a solid foundation, but we're transparent about current constraints and our roadmap for future enhancements:

🎯 User Experience Challenges

  • Seed Entry Complexity: Typing 12-24 BIP39 words using T9-style numeric mapping is tedious. Future: Pre-generated seed cards, QR import options.
  • Address Verification: Limited display size makes verifying long Bitcoin addresses difficult. Future: Address checksums, visual confirmation patterns.
  • Learning Curve: Command syntax requires training. Future: Context-sensitive help menus, interactive tutorials.

🔐 Security Considerations

  • Shoulder Surfing: PIN entry visible to observers. Mitigation: Use privacy screens, scrambled keypads, biometric enhancement.
  • Physical Security: Low-cost hardware may lack tamper resistance. Recommendation: Use secure element chips for production deployments.
  • Supply Chain: DIY builds bypass this, but commercial products need verification. Future: Open hardware certification program.

🛠️ Error Recovery & Input Buffering (v2.0 Design)

One of our most important v2.0 enhancements addresses error recovery through input buffering:

Input Buffer Pattern

  • 0-9: Append to input buffer (non-destructive)
  • #: Clear buffer / Backspace last character
  • *: Confirm buffer & execute operation
  • ##: Emergency abort (cancel entire operation)

Example: Enter PIN 9999:
User types: 8 → Display: [8___] (buffered, not committed)
User presses: # → Display: [____] (buffer cleared)
User types: 9999 → Display: [9999] (waiting for confirmation)
User presses: * → Display: PIN CONFIRMED

Context-Aware Confirmations

Different applications require different security levels:

  • Hardware Wallet (Speed Priority): Single * confirmation for small transactions, double ** for large amounts.
  • Institutional (Security Priority): Multiple confirmations, review windows, superior officer authorization codes.
  • Bitcoin ATM (Public Use): On-screen preview + timeout + explicit confirmation to prevent accidental transactions.

📊 Command Namespace Expansion (v2.0+)

v1.0 is limited to 10 commands per library (#0-#9). v2.0 will introduce multiple expansion strategies:

Expansion Strategies

  • Multi-Key Sequences: #11, #12, #21 for hierarchical command trees (unlimited expansion)
  • Mode Switching: Enter Bitcoin Mode, Lightning Mode, etc.—each with full 0-9 command space
  • Library Namespaces: Different libraries override the same command keys (already implemented in v1.0)
  • Reserved * Commands: v1.0 reserves *0-*9 for future advanced/batch operations

v2.0 Command Additions (Currently Reserved)

  • Bitcoin Library: *4-*8 reserved for batch transaction building (NEW_TX, ADD_INPUT, ADD_OUTPUT, SIGN_TX, BROADCAST)
  • Lightning Library: Advanced channel management, routing optimization, streaming payments
  • Industrial Library: *4-*8 reserved for GPIO, PWM, sensor operations
  • Auth Library: *4-*8 reserved for TOTP generation, digital signatures, certificate management

🚀 Protocol Versioning & Backward Compatibility

  • v1.0 Guarantee: All v1.0 devices will work forever. No breaking changes.
  • v2.0 Extensions: Additive only. Devices advertise capabilities, fall back gracefully.
  • Firmware Updates: Over-the-air updates for internet-connected devices. Manual update via SD card for air-gapped systems.

💬 Community Input

We're actively seeking feedback from:

  • Security Researchers: Help us identify vulnerabilities, side-channel attacks, protocol weaknesses
  • Hardware Manufacturers: What features would make FatCat more adoptable?
  • Institutional Users: What compliance, audit, and governance features are needed?
  • Developers: Contribute libraries, demos, improvements to the protocol
Philosophy: These "limitations" are inherent to any interface language—just like programming languages have finite keywords, musical notation has 12 notes, and human languages have limited phonemes. The 12-button constraint isn't a bug; it's a feature that forces elegant, universal design.

📜 Dual Licensing Framework

FatCat Protocol™ uses a dual licensing model to encourage widespread adoption while sustaining commercial development:

🆓 MIT License

For: Personal use, hobbyists, small businesses, non-profits, educational institutions

Revenue Threshold: Annual revenue < $1,000,000 USD

Terms: Free to use, modify, distribute. Attribution required. No warranty.

Use Cases: DIY hardware wallets, personal projects, small Bitcoin ATMs, educational demonstrations, open-source contributions

💼 Commercial License

For: Enterprises, exchanges, financial institutions, manufacturers, large-scale deployments

Revenue Threshold: Annual revenue ≥ $1,000,000 USD

Terms: Contact for pricing. Includes support, certification, compliance assistance, priority features.

Use Cases: Exchange custody systems, Central Bank operations, commercial ATM networks, institutional multi-sig, regulated financial services

Philosophy: Keep the barriers low for individuals and small businesses (MIT license), while commercial enterprises that benefit from standardization contribute to protocol development and maintenance (Commercial license). This ensures long-term sustainability while maximizing adoption.

🎮 Try the Demos

Explore the interactive demonstrations in the left sidebar to see how FatCat Protocol™ works across different industries and scales. Each demo is fully functional and showcases real-world use cases.

Want to build your own FatCat device? Visit the Web IDE to start programming with the FatCat Protocol™ standard.