Anyone Can Pay

The Anyone-Can-Pay is a Lock Script that enables users to send any amount of CKB or sUDT to a Cell without the traditional minimum 61 CKBytes requirement. It is particularly useful for small-value token transfers and introduces optional minimum transfer thresholds to mitigate potential DDoS attacks from spam micro-transactions.

How It Works

The Anyone-Can-Pay Lock Script extends the default secp256k1-blake2b-sighash-all lock and supports two unlocking modes:

1. Signature-Based Unlocking: If a valid signature matching the lock’s public key hash is provided, the Cell behaves like a normal one and can be spent freely by the owner.

2. Non-Signature Unlocking (Anyone Can Pay): If no signature is provided, the lock allows anyone to add CKB or UDT to the cell, subject to strict validation rules:

   • Only one input and one output Cell are allowed per unique Lock + Type Script pair.
   • The CKB and UDT in the output must not be less than those in the input.
   • Optional minimum thresholds (e.g., 10^x shannons or UDT base units) must be met if specified.
   • Cells with Type Scripts must follow the sUDT format (≥16 bytes of data).
   • Prevents unauthorized merging or splitting of Anyone-Can-Pay Cells to avoid storage bloat and fee inefficiencies.

The Lock Script uses an argument format like <public key hash> <CKByte minimum> <UDT minimum>, allowing the Cell owner to configure minimum acceptable deposits. This design offers a secure, flexible way to support micro-transactions on CKB without overburdening the network.

Reference RFC

Deployment

• Mainnet

parameter	value
code_hash	0xd369597ff47f29fbc0d47d2e3775370d1250b85140c670e4718af712983a2354
hash_type	type
tx_hash	0x4153a2014952d7cac45f285ce9a7c5c0c0e1b21f2d378b82ac1433cb11c25c4d
index	0x0
dep_type	dep_group

• Testnet

parameter	value
code_hash	0x3419a1c09eb2567f6552ee7a8ecffd64155cffe0f1796e6e61ec088d740c1356
hash_type	type
tx_hash	0xec26b0f85ed839ece5f11c4c4e837ec359f5adc4420410f6453b1f6b60fb96a6
index	0x0
dep_type	dep_group