RFID Authentication via External Cryptographic Coupons
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Solution Overview
Problem
Existing Digital Rights Management (DRM) systems face challenges in protecting digital content from unauthorized copying and distribution due to the inconvenience of managing and sharing symmetric keys, and the need for powerful processors in verifier devices for authentication, especially when dealing with computationally weak prover devices like RFID tags.
Innovation Solution
An authentication method using cryptographic coupons where reduced-coupons are stored externally, such as on digital-content storage means like CDs or DVDs, allowing a computationally weak prover device like an RFID tag to authenticate with a verifier device by regenerating pseudo-random numbers using a regeneration key, reducing computational load and storage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If symmetric key algorithms are used for authentication, then security is improved, but key management complexity and exposure risk increase
Solution Approach 1:
The patent applies asymmetry by using public-key cryptography instead of symmetric keys. The prover device holds a private key while the verifier device holds a public key, eliminating the need for secure key sharing and management between devices. This asymmetric approach maintains authentication security while removing key management complexity.
2Device complexity
If public-key algorithms are used for authentication, then key management is simplified, but computational requirements and processor power increase
Solution Approach 1:
The patent segments the authentication protocol into two distinct roles: a computationally weak prover device that performs minimal operations (signing a challenge), and a computationally strong verifier device that performs the intensive operations (verifying the signature). This segmentation allows public-key authentication while accommodating devices with limited processing power.
Solution Approach 2:
The verifier device pre-generates and stores multiple challenges before the authentication protocol executes. During authentication, the verifier simply selects a pre-generated challenge rather than generating it on-the-fly, reducing the computational burden on the prover device and allowing the use of computationally weak devices.
3Quantity of substance
If reduced-coupons are stored externally on digital-content storage means, then storage requirements on prover device are reduced, but authentication protocol complexity increases
Solution Approach 1:
The patent introduces an intermediary element: the digital-content storage means (CD/DVD) acts as a mediator between the prover device and verifier device. The storage means carries pre-generated challenges that the verifier uses during authentication, eliminating the need for the verifier to generate challenges computationally and reducing the prover's storage requirements while managing protocol complexity through this intermediary.
Data Source
Figure 1
AI summary
An authentication method of a prover device (1) by a verifier device (2) by means of cryptographic coupons is provided for, wherein a coupon comprises, on one hand, a pseudo-random number ri, where i is an index for labeling the coupon, and, on the other hand, a reduced-coupon xi such that xi = f(ri), where f is a predetermined one-way function, comprising at least the following steps: the verifier device (2) sends a challenge consisting of a random value c to the prover device (1); the prover device (1) sends to the verifier device (2) a response y calculated by using a pseudo-random number ri, said challenge c, and a secret key s belonging to the prover device (1); and the verifier device checks the validity of said response y based on the challenge c, the reduced-coupon xi corresponding to said pseudo-random number ri, and a public key V corresponding to said secret key s. According to the invention, the verifier device (2) receives said reduced-coupon xi from a source (3) external to the prover device (1). Application to Digital Rights Management.