Dynamic Challenge-Response Authentication for Secure Server Client Interaction
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Solution Overview
Problem
Existing cookie-based systems for establishing a trusted relationship between a server and a client device are vulnerable to attacks where a malicious third party can emulate the user device/browser combination by obtaining static data.
Innovation Solution
A method involving dynamic challenges and responses, where the client device receives challenges from the server, determines responses, and provides a composite response that allows the server to verify the client device's identity without relying on static data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If static data is used to identify the user device, then the authentication process is simple, but the system becomes vulnerable to emulation attacks by third parties
Solution Approach 1:
The patent transitions from static device identification data to dynamic challenge-response authentication. The server issues challenges that require computational work (proof-of-work) and the client responds with time-dependent values. This dynamic approach ensures that even if an attacker obtains current authentication data, it becomes invalid quickly, preventing emulation attacks while maintaining operational simplicity through automated challenge-response exchanges.
2Reliability
If cookies are encrypted to reduce attack risk, then security is improved, but key management complexity increases
Solution Approach 1:
The patent extracts the cryptographic key management burden from the client device and places it entirely on the server. The server generates and manages all encryption keys, while the client only stores opaque cookie values without any associated key material. This eliminates the need for complex client-side key management while maintaining encrypted cookie security, as the server retains full control over key generation, rotation, and revocation.
3Measurement precision
If device fingerprinting is used to establish trusted relationship, then the ability to identify legitimate devices is improved, but the risk of fingerprint theft and emulation increases
Solution Approach 1:
The patent implements preliminary binding of device identifiers to authentication credentials during initial setup. The server binds the device fingerprint to the user's account credentials and stores this binding securely. During subsequent authentications, the server verifies that the presented credentials match the bound device fingerprint. This preliminary binding prevents fingerprint theft from being useful, as stolen fingerprints cannot be used without the corresponding bound credentials, and the binding relationship is verified before granting access.
Data Source
AI summary
A method of maintaining a secure relationship between a client device and a server is described. The client device receives a first challenge from the server and determines and provides a first response to the first challenge. A cookie is established associated with the secure relationship. This cookie is shared between the client and the server. To establish the secure relationship in a later interaction, the client provides the cookie to the server. The server then provides both the first challenge and a second challenge, to which the client determines a first response and a second response. The client then provides a composite response from which the first response and the second response are derivable by the server, allowing the server to be assured that the secure relationship exists. Each challenge uses a challenge function adapted to provide a fingerprint of the client device. Methods at both client and server, and suitably configured client and server, are also described.