Banknote-Based Key Derivation for Anonymous Payment Backup
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Solution Overview
Problem
Existing cashless payment methods lack the convenience and security of physical cash, particularly in situations where immediate, anonymous payments are required without relying on bank accounts or internet connectivity, and they do not offer a backup mechanism in case of device loss or damage.
Innovation Solution
A banknote with a processor and memory stores a unique cryptographic key, allowing it to derive a private key for an anonymous account on a computer system, enabling both cash-based and cashless payments, with the banknote serving as a security anchor and backup.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If cashless payment methods are used, then payment processing efficiency is improved, but security and availability in case of device loss or damage deteriorates
Solution Approach 1:
The payment system is segmented into two independent components: a banknote with cryptographic key and a computer system with derived account. This segmentation allows the cryptographic key to be stored on the physical banknote while the account and processing occur on the computer system, providing both efficiency and a security backup through physical separation.
Solution Approach 2:
The banknote serves as an intermediary carrier of the cryptographic key between the user and the computer system. The key derivation process uses the banknote's key as a seed to generate the computer system's private key, creating a trusted link that enables both efficient digital processing and secure backup through the physical banknote.
2Productivity
If bank accounts are required for payments, then efficient payment processing is improved, but ease of use and accessibility deteriorates
Solution Approach 1:
The banknote is given multi-functionality by serving both as traditional cash and as a cryptographic key carrier for digital payments. This allows users to perform efficient cashless payments while maintaining the simplicity and accessibility of physical cash, eliminating the need for separate bank accounts or digital wallets.
Solution Approach 2:
The system enables self-service payments where the user's own banknote provides the cryptographic key for their computer system account. This eliminates dependency on external bank infrastructure or third-party payment processors, making payments as accessible as using physical cash while maintaining digital efficiency.
3Productivity
If cryptographic keys are stored on computer systems, then payment processing efficiency is improved, but security against device loss deteriorates
Solution Approach 1:
The system prepares a backup cryptographic key stored on the physical banknote before any device loss occurs. This prior cushioning ensures that even if the computer system is lost or damaged, the user can recover their payment capabilities by deriving a new key from the banknote, preventing total loss of access to funds.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
The invention relates to a method for deriving a private cryptographic key (250) of an anonymous account, which is dependent on an anonymous banknote account individually assigned to a banknote (100), using the banknote (100). The banknote (100) comprises a security element (102) with a processor (124) and a memory (120) containing program instructions (128). A banknote-specific cryptographic key (118) is stored in a protected memory area (122) of the memory (120) of the security element (102). The private cryptographic key (250) for the dependent anonymous account is derived using a one-way function and the banknote-specific cryptographic key (118) and serves a computer system (180, 190) for generating cryptograms to authorize payment from the dependent account.