Fast ciphering key search for WLAN receivers

摘要

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.

主权项

1. A WLAN (Wireless Local Area Network) receiver comprising:
a ciphering key management circuit configured to control use of cipher keys for decrypting received data, wherein said ciphering key management circuit comprises a memory circuit configured to store a hash table having a first and a second set of entries, said first set of entries including transmitter address data comprised of a predetermined number of lower bits of a respective transmitter address, said second set of entries including at least one cipher key, wherein said ciphering key management circuit is configured to determine whether a transmitter address obtained from an incoming data frame matches said transmitter address data in said first set of entries, and if so, determine a cipher key corresponding to the transmitter address, wherein the cipher key is included in said second set of entries and is configured for use in decrypting said received data; wherein said transmitter address data included in said first set of entries is comprised of a number of lower bits of a respective transmitter address, wherein said first set of entries comprises a number of sub-fields, each configured to store transmitter address data of a different transmitter, wherein the ciphering key management circuit is configured to dynamically change the number of sub-fields by executing software instructions, and wherein said ciphering key management circuit is configured to reduce said number of lower bits responsive to an increase in said number of sub-fields; wherein said second set of entries comprises a number of table entries each configured to store at least one cipher key pertaining to a different transmitter, wherein each table entry has a fixed length independent from the length of the hash table; wherein the length of the hash table is given by the length of said first set of entries and the length of said second set of entries, said length of said second set of entries being dependent on said fixed length of said table entries and the number of table entries in said second set of entries, wherein the number of active sub-fields in said first set of entries is equal to the number of table entries in said second set of entries.