Biometric Key Generation Using Permuted Secret Extraction Codes
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Solution Overview
Problem
Existing systems for generating cryptographic keys from physical identifiers are limited in their ability to derive multiple keys from biometric data while maintaining security and convenience, particularly in scenarios where noisy measurements are involved and multiple parties are involved in communication.
Innovation Solution
The method extends the collection of secret extraction codes by adding permuted versions, ensuring that each biometric measurement can map to multiple cryptographic keys, thereby enhancing the robustness and security of key derivation across different communication channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single secret extraction code is used to derive cryptographic keys from biometric data, then the key derivation process is simple, but multiple cryptographic keys cannot be derived for secure communications with multiple parties
Solution Approach 1:
The patent segments a single complex secret extraction code into multiple simpler codes, each capable of deriving cryptographic keys. By dividing the code collection into manageable segments, the system can derive multiple keys while keeping individual code complexities low, thus resolving the contradiction between key derivation versatility and code complexity.
Solution Approach 2:
The patent creates a universal code collection where each secret extraction code can serve multiple purposes - deriving cryptographic keys for different parties. This multi-functionality allows a single code structure to handle various key derivation scenarios, improving adaptability without proportionally increasing overall system complexity.
2Ease of operation
If biometric measurements are used directly for key derivation, then the process is convenient for users, but noisy measurements reduce key derivation reliability
Solution Approach 1:
The patent implements beforehand cushioning by designing the secret extraction code to anticipate and compensate for measurement noise before key derivation occurs. The code structure includes built-in tolerance mechanisms that cushion against variations in biometric measurements, ensuring reliable key derivation even when users provide noisy measurements during authentication.
Solution Approach 2:
The patent applies parameter changes by adjusting the sensitivity thresholds and acceptance ranges within the secret extraction code to accommodate noisy biometric measurements. By dynamically modifying these parameters, the system maintains both user convenience (accepting natural measurement variations) and derivation reliability (ensuring consistent key generation).
3Ease of operation
If helper data is sent over a public authenticated channel, then the system provides convenience for key derivation at terminals, but the helper data may leak information about the cryptographic key
Solution Approach 1:
The patent extracts only the necessary minimal information into helper data that can be safely transmitted over public channels. By separating and extracting only the non-sensitive components needed for terminal key derivation, the system enables convenient local key generation while minimizing information leakage about the actual cryptographic keys.
Solution Approach 2:
The patent introduces the secret extraction code as an intermediary that mediates between the biometric data and the cryptographic key. This intermediary structure allows helper data to be transmitted publicly while preventing direct exposure of key information, as the code acts as a protective layer that transforms public helper data into secure keys without leaking intermediate information.
4Device complexity
If the same cryptographic key is used for communications with multiple parties, then key management is simplified, but security is compromised as parties can eavesdrop on each other
Solution Approach 1:
The patent segments the key derivation process to generate distinct cryptographic keys for different communication parties, even though the underlying secret extraction mechanism remains unified. This segmentation approach maintains relatively simple key management (using the same biometric source) while ensuring security (different keys prevent eavesdropping), resolving the contradiction between management simplicity and security.
Data Source
AI summary
A method of generating a key for encrypting communications between first and second terminals includes obtaining a measurement of characteristics of a physical identifier of a user; and extracting a key from the physical identifier using a code selected from a collection of codes. Each code in the collection defines an ordered mapping from a set of values of the characteristics to a set of keys. The collection of codes includes at least one code in which the ordered mapping is a permutation of the ordered mapping of one of the other codes in the collection.