Satoshi Protocol

Terminology & Abbreviation

Abbr.	Description
Addr	The base58 format address generated from PK
BC	The bridge smart contract in Near, assuming its contract ID is bridge.near
Bitcoin Relayer	Help to broadcast Bitcoin withdrawal transactions to Bitcoin network.
CA	CSNA Assistant, lives on the user's side, help user invoking BTC wallet to sign message.
CSNA	Chain signature Near account, a sub-account of BC, uses dAddr as its ID. This is the user’s non-custodian near account.
dAddr	The user’s exclusive deposit address in base58 format generated from dPK
dPK	a Bitcoin public key generated through NEAR Chain Abastaction where PK is the path and BC is the predecessor account
DTL	Deposit Bitcoin Tx Listener.
MDS	Message delivery Service.
MetaTx Relayer	NEAR Meta-Transaction Relayer for NSP message operations.
nPK	A Near EdDSA public key generated through NEAR Chain Abstraction where PK is the path and BC is the predecessor account
NSP frontend	the frontend pages of the bridge dapp lived on the user’s side, mainly used for deposit and withdrawal.
PK	User’s bitcoin public key whose corresponding secret key will be used to sign messages
smTX	The signed Near Tx comes from a user’s message.
ST	Signing Trigger, help to trigger BC to request Chain Signature for withdrawal TXs.
TC	Mapping Token Contract, currently means nBTC token contract.
UM	UTXO Management.
WTL	Withdrawal Bitcoin Tx Listener.

Near Satoshi Protocol (NSP) is an bridge protocol based on Near Chain-Abstraction which not only provide assets bridge ability but allow source chain users to directly access NEAR dApps. NSP actually pushes BTC holders’ web3 user experience to a new level: With NSP, any BTC holder can join the whole NEAR network ecosystem, without introducing any new wallet, or any new key pairs. Just using their familiar BTC wallet, BTC holders can play with all dApps on the NEAR network, with only BTC as on-chain gas, and enjoy the seconds finality speed of the NEAR network.

Let’s see how NSP can achieve that. There are roughly 3 basic questions involved in any bridge:

• How to bridge assets out of Bitcoin? Aka, deposit.

• How to use those bridged assets?

• How to bridge assets back to Bitcoin? Aka, withdrawal.