US Patent No. 9,225,518


Patent No. 9,225,518
Issue Date December 29, 2015
Title Method Of Providing Fresh Keys For Message Authentication
Inventorship Semyon B. Mizikovsky, Morganville, NJ (US)
Robert J. Rance, Andover, MA (US)
Assignee Alcatel Lucent, Boulogne-Billancourt (FR)

Claim of US Patent No. 9,225,518

1. A method, comprising:
providing, from a mobile unit, at least one access request message including information indicative of a message authentication
code formed using a first key, the first key being derived by the mobile unit from a second key and a first counter, the second
key being derived from a third key established for a security session between the mobile unit and an authenticator, wherein
the first counter is only incremented in response to an access request message provided by the mobile unit for a handoff of
the mobile unit;

initiating, in response to providing said at least one access request message, a key lock mode in which the counter cannot
be changed; and

exiting the key lock mode in response to establishing a connection with at least one base station based on said at least one
access request message.