Offline payment authorization with deferred settlement.
Bingo and Bongo are two monkeys on Mars.
There is no internet.
They still need to pay.
Contents
Bingo-Bongo Protocol enables two devices to authorize a payment while offline (via NFC or Bluetooth), and settle it later once network connectivity is restored.
- Offline-first payment authorization
- Cryptographically signed commitments (vouchers)
- Risk-limited by design
- Compatible with Account Abstraction (ERC-4337)
This protocol is designed as an offline fallback, not a replacement for online payment systems.
Internet connectivity is not always available.
In many environments — emerging markets, large events, transportation, or during network outages — mobile payments fail simply because devices cannot reach the network.
Most crypto payment systems require:
- always-on connectivity
- immediate access to global state
- real-time transaction submission
Bingo-Bongo Protocol separates payment authorization from settlement, allowing payments to be agreed upon offline and finalized later.
The protocol splits a payment into two phases:
- Offline authorization
- Online settlement
- Instant crypto acquiring SDK with deferred settlement
While offline:
- Bingo (payer) signs a payment commitment (voucher)
- Bongo (recipient) verifies and stores the voucher locally
Once either party is online:
- The voucher is submitted for settlement
- Funds are transferred on-chain
- Bingo — the payer authorizing a payment
- Bongo — the recipient collecting authorization
- Voucher — a signed offline payment commitment
- Settlement — execution of the voucher on a settlement layer
- Offline limit — maximum value that can be authorized while offline
To set correct expectations, Bingo-Bongo is:
- ❌ Not fully trustless offline money
- ❌ Not infinite offline spending
- ❌ Not a replacement for Visa, Apple Pay, or online crypto payments
- ❌ Not designed for large-value transfers
The protocol intentionally trades off full trustlessness for usability in offline environments.
- Devices can remain offline for a limited time.
- One of the parties may behave maliciously
- Network connection will be restored over time.
- Attempts to double spend while offline
- Repeat previously signed vouchers
- Lost or compromised device
- Clear restrictions on offline spending
- Disposable numbers per voucher
- Expiration timestamps
- Deterministic on-chain verification
The protocol consists of the following components:
- Mobile SDK
- NFC for discoveries
- Bluetooth for data transfer
- Voucher format
- Structured signed message (EIP-712 compatible).
- Smart account
- Account abstraction compliant with ERC-4337.
- Relayer/Bandler
- Sends settlement transactions online.
ERC-4337 is used internally to provide flexible verification. custom nonce management and gas abstraction.
The voucher represents an authorized offline payment.
At a minimum, it contains:
- payer's address (Bingo)
- recipient's address (Bongo)
- asset identifier
- amount
- unique one-time number
- expiration timestamp
- cryptographic signature
Vouchers are one-time use and become invalid once paid for or expired.
When the connection is restored:
- The voucher is transferred to the settlement level.
- The payer’s smart account checks:
- signature
- one-time uniqueness
- validity period
- available offline balance
- Funds are transferred
- The voucher is permanently marked as used.
Settlement can be initiated by either party or a third party relay.
- Autonomous payments to sellers
- Events and festivals with congested networks
- Developing markets with unstable connections
- Backup of the payment system during failures
- Phone to phone payments without POS equipment
Current Status: Concept/Early PoC
Planned stages:
- Voucher specification v0.1
- Reference smart account ERC-4337.
- Mobile SDK prototype
- Comprehensive demo with two devices
The Bingo-Bongo protocol is built on obvious compromises:
- Limited risk instead of unlimited trust
- Delay of settlement rather than immediate finality
- Simplicity over protocol maximalism
Offline payments are not free. This protocol clearly defines cost and risk.
This project is experimental.
It is not intended for production use without proper safety checks, risk assessments, and normative consideration.
TBD