Patent ID: 7426636
Filing Date: 2008-09-16
Classification: H04L

Abstract:
1. A method of providing compact secure data communication, the method comprising the computer-implemented steps of: receiving from a sender over a non-secure data communication network, a data packet comprising a security parameter index value, an explicit sequence value, a compressed encrypted payload, and a first authentication tag value; estimating an implicit sequence value based on the explicit sequence value; determining whether the packet has been replayed, based on the implicit sequence value; when the packet has not been replayed; accepting the data packet when a second authentication tag value generated by the authentication function matches the first authentication tag value, wherein the estimating step comprises the steps of: for the explicit sequence value E, estimating the implicit sequence value as a value I defined by I=2 where A is selected from a set {R−1, R, R+1} such that I is closest to a value 2 wherein S represents a prior explicit sequence value; wherein a rollover value R counts a number of times that S has incremented to its maximum value (2 wherein if the value of R is zero, then I is estimated as E; wherein if the value of R is 2