WLAN Receiver Hash Table for Fast Cipher Key Search
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Solution Overview
Problem
Prior art WLAN receivers face inefficiencies in searching for the correct cipher key due to software-driven serial searches, which are time-consuming and prone to accuracy issues, especially when a large number of cipher keys are stored, requiring significant buffering.
Innovation Solution
A WLAN receiver employs a hash table with separate portions for transmitter address data and cipher keys, allowing for rapid key determination through hardware-based matching, reducing memory usage and enabling dynamic key management without blocking searches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a software-driven serial search is used to find the correct cipher key, then the receiver can handle a large number of stored cipher keys, but the search time becomes substantially long and processing efficiency deteriorates
Solution Approach 1:
The patent replaces the software-driven serial search mechanism with a hardware-based parallel search mechanism. The hash table structure with multiple entries allows simultaneous comparison of multiple cipher keys against the received signal, transforming a sequential software process into a parallel hardware operation. This substitution dramatically improves search efficiency while maintaining the ability to handle numerous stored keys.
Solution Approach 2:
The patent segments the cipher key storage and search process into discrete hash table entries, each containing a cipher key and its corresponding hash value. This segmentation allows independent parallel processing of multiple key comparisons, enabling the system to evaluate numerous cipher keys simultaneously rather than sequentially, thus resolving the contradiction between handling many keys and maintaining search efficiency.
2Ease of operation
If a software-driven serial search is used to determine the correct cipher key, then the search can be performed, but accuracy and precision problems occur in performing the determination
Solution Approach 1:
The patent replaces the imprecise software-based determination process with a hardware-based comparison mechanism that directly evaluates multiple cipher keys in parallel. The hash table structure enables deterministic comparison operations with defined priority rules, eliminating the ambiguity and precision issues inherent in software serial search. The hardware implementation provides more reliable and accurate key identification.
3Adaptability or versatility
If a large number of cipher keys are stored at the receiver for serial search, then the system supports multiple transmitters, but significant buffering capacity is required
Solution Approach 1:
The patent segments the buffering requirement into individual hash table entries, each storing a cipher key and its hash value in a structured format. This segmentation allows efficient memory utilization where only the essential key information is buffered rather than large amounts of raw data. The hash table structure enables compact storage that supports multiple transmitters while minimizing the total buffering capacity required.
Solution Approach 2:
The patent performs preliminary hashing of cipher keys during the key setup phase, storing only the hash values and key identifiers in the hash table. This preliminary action eliminates the need to buffer large amounts of encrypted data for later processing, as the search can be performed directly on the pre-computed hash values, significantly reducing the buffering capacity needed while maintaining support for multiple transmitters.
Data Source
AI summary
A ciphering key management technique for use in a WLAN receiver is provided where a hash table is stored that has a first and a second table portion. The first table portion stores transmitter address data and the second table portion stores at least one cipher key. It is determined whether a transmitter address matches transmitter address data in the first table portion, and if so, a corresponding cipher key stored in the second table portion is determined for use in decrypting the received data. The hash table technique allows for a fast search for the correct cipher key. Embodiments are described that allow for dynamically adding and removing keys without blocking the search.