YC (Younkert Captitals) utilizes blockchain and smart contract technologies to facilitate fiat currency exchange via a decentralized cross-border trading platform, with settlement ledgers and other data recorded on-chain. Adhering to global regulatory standards, legal requirements, and financial ISO international standards, YC builds a public blockchain network protocol. This protocol establishes an effective connection between financial institutions ledgers and blockchain distributed ledgers, enabling inter-chain interoperability for banking transactions and data. It supports online fiat currency exchange, trading transfers, and offline payment conversions, meeting transaction processing efficiency and regulatory privacy protection requirements, and facilitating complex international financial activities such as cross-border payments.