Cryptographic Coupon Reloading via Keyed Pseudo-Random Authentication
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing cryptographic protocols for coupon-reloading devices lack secure authentication methods, making them vulnerable to denial-of-service attacks, particularly in insecure communication environments where a computationally weak prover device cannot verify the legitimacy of a coupon-reloading device.
Innovation Solution
A method involving a pseudo-random number generated using a regeneration key and a keyed pseudo-random function, where the reloading device verifies a token and authentication key to ensure the legitimacy of the coupon-reloading process, allowing secure storage and refreshment of reduced-coupons in the coupon-consuming device without requiring additional circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a coupon-consuming device allows reloading from any device, then coupon reloading is simple and fast, but the system becomes vulnerable to denial-of-service attacks from fake reloading devices
Solution Approach 1:
The patent introduces an authentication key Q as an intermediary element that mediates between the coupon-consuming device and the reloading device. This key serves as a trust intermediary that allows the consuming device to verify the legitimacy of the reloading device without requiring complex mutual authentication protocols, thus maintaining fast reloading while preventing denial-of-service attacks.
Solution Approach 2:
The authentication key Q is pre-loaded into the coupon-consuming device during fabrication. This preliminary action enables the device to perform quick authentication of reloading devices without requiring complex real-time verification, thus maintaining fast coupon reloading speed while ensuring security against fake reloading devices.
2Reliability
If the coupon-consuming device performs full authentication verification, then security is improved, but the computational burden on the weak prover device increases
Solution Approach 1:
The authentication process is segmented into two parts: the authentication key Q and the token T. The RFID tag (weak prover device) only needs to verify the token using the pre-loaded key Q, which is a simple cryptographic verification. The complex authentication logic and key management remain on the stronger reloading device, thus maintaining security while minimizing computational burden on the weak device.
Solution Approach 2:
The patent uses a cryptographic copy approach where the authentication key Q is copied into the coupon-consuming device during fabrication. This allows the weak device to perform lightweight verification of reloading devices without needing to implement complex authentication protocols, thus maintaining security with minimal computational energy consumption.
3Reliability
If additional authentication circuitry is added to the verifier device, then authentication capability is improved, but device complexity and cost increase
Solution Approach 1:
The authentication key Q is designed to serve multiple functions: it is used both for regenerating coupons (ri = PRFi(K, i)) and for authenticating reloading devices (verifying token T). This multi-functionality eliminates the need for separate authentication circuitry in the coupon-consuming device, maintaining simplicity while providing robust authentication capability.
Solution Approach 2:
The patent merges the coupon regeneration function and the authentication function into a single cryptographic primitive (the keyed pseudo-random function PRF). The same key Q used for coupon generation is also used for authentication, combining two functions into one and avoiding additional circuitry complexity.
Data Source
AI summary
A system and a method for cryptographic reduced-coupon reloading are provided, where a coupon includes a pseudo-random number ri=PRFK(i), where i is an index for labeling the coupon, PRF is a predetermined pseudo-random function and K is a regeneration key, and a “reduced-coupon” xi=ƒ(ri), where ƒ is a predetermined one-way function, where: a candidate device and a second device acquire a common value of a token T, the candidate device transmits a verification value vT to the second device, the second device verifies whether the verification value is equal to PRF′Q(T), where PRF′ is a predetermined keyed pseudo-random function identical to, or derived from, the pseudo-random function PRF, where Q is an authentication key owned by the second device and known to the candidate device provided the candidate device is a legitimate reloading device, and if the verification is positive, one or several reduced-coupon(s) provided by the candidate device are stored in the second device.