Privacy Payment Card: Structure and Operation of the Secret Card Based on PayFi @humafinance , @rainbowdotme , @nesaorg The privacy payment card is a concept that describes a payment structure designed to meet both payment convenience and personal data protection, connecting the technical characteristics of Huma Finance's PayFi infrastructure, the privacy AI layer Nesa, and the mobile wallet interface Rainbow into a single flow. As of January 2026, there is no official integrated service among the three projects, but the purpose is to explain how personal data protection can be implemented in the payment process based on the actual functions and roles each technology provides. The starting point of the payment is the infrastructure of Huma Finance, which provides the PayFi card payment structure. Huma Finance operates a PayFi stack focused on real-time payment settlement and liquidity provision, processing card payments based on stablecoins and on-chain settlement records. In this process, the payment amount and settlement results are recorded in a verifiable form, but the detailed contextual information of the payment is not exposed on-chain. In fact, Huma Finance has a history of processing numerous payment and financial transactions, and the PayFi structure focuses on the financial functions of payment processing and fund movement. The protection of consumption patterns and metadata generated during the payment process is explained through Nesa's privacy AI layer. Nesa operates a layer 1 blockchain aimed at reliable AI computation and encryption, presenting a structure designed to enable computation and verification without exposing the data itself through Equivariant Encryption and zero-knowledge proof technology. Consumption metadata such as amount, frequency, and category generated at the time of payment is processed in an encrypted state, and this data can be utilized for anomaly detection or verification procedures without being restored to plaintext, as explained in the technical documentation. This method distinguishes itself from existing payment networks in that it is designed to prevent centralized collection of data. Users can understand this structure as managing their payment history through the Rainbow mobile wallet. Rainbow is a non-custodial wallet that allows users to directly store their private keys and provides an interface for transaction signing and asset management. Within the wallet, transaction history is stored on the user's device, and what information is shared externally is determined by the user's choice. Rainbow serves as a user experience layer that visually confirms and manages payment results, supporting Ethereum and multiple chains. An important feature of this structure is that payment records are not concentrated in a single entity in a complete form. Users can check their entire payment history through the Rainbow wallet, but only encrypted verification information remains on the network, and only the minimum financial data necessary for settlement is recorded in Huma's PayFi infrastructure. Nesa's network retains encrypted metadata and verification results, ensuring that each layer holds only different information. This distributed structure operates in a way that clearly separates payment processing, data protection, and user interface, which can be described as a core structural characteristic of the privacy payment card. As a result, the privacy payment card can be understood as protecting consumption pattern data, which was previously collected by existing payment systems, through encryption and a distributed structure while delegating the functions of payment settlement and user management to each technology layer. This serves as a structural example of how payment and personal data protection can be explained separately based on the functionalities of the existing PayFi infrastructure, privacy AI blockchain, and non-custodial mobile wallet. $HUMA $NESA $RNBW $SOL $ETH