US 7,116,668 B2 · Method for time stamp-based replay protection and PDSN synchronization at a PCF

Abstract

A packet control function (PCF) exchanging messages with a packet data serving node (PDSN) in a wireless communication network guards against malicious or erroneous message replay by checking the “reasonableness” of PDSN time stamps in registration messages it receives over its PDSN interface. Received messages that are too old are rejected by the PCF, even if otherwise valid. A configurable time threshold may be set at the PCF that determines the allowable maximum age of a received message. Further, because messages received from the PDSN contain echoed identifier values generated by the PCF, the PCF may implement identifier value function generation that insures no repeated identifier values over a desired interval. The desired interval is set larger than the allowable message age to further guard against attempted message replay.

Claims31

Dependent claims

A method of authenticating registration reply messages received by a PCF that are purportedly responsive to registration messages previously sent by the PCF to a PDSN, said method comprising:

determining a verification threshold for validating time stamps in registration reply messages;
generating a sequence of message numbers for sequential use in a series of successive registration messages sent by said PCF to said PDSN, said sequence of message numbers having a repeat interval greater than said verification threshold;
inserting said sequential message numbers into successive registration messages sent by said PCF to said PDSN;
receiving a registration reply message at said PCF presumptively sent by said PDSN in response to a registration message previously sent by said PCF, said registration reply message containing a time stamp and a message number;
validating said message number in said registration reply message by comparing said message number in said registration reply message to the message number in a corresponding registration message sent by said PCF;
if said message number is valid, validating said time stamp in the said registration reply.

3 more elements

A method of authenticating a second registration message received by a PCF that is purportedly responsive to a first registration message previously sent by the PCF to the PDSN, said method comprising:

inserting a message number into said first registration message;
sending said first registration message from said PCF to said PDSN;
receiving said second registration message at said PCF responsive to said first registration message, said second registration message containing a time stamp and said message number from said first registration message;
authenticating said second registration message based on said message number and said time stamp by validating said message number in said second registration message and if said message number is valid, validating said time stamp in said second registration message, wherein validating said time stamp in said second registration message comprises:
comparing said time stamp in said second registration message to said time stamp in said first registration message;
accepting said second registration message if said time stamp in said second registration message equals said time stamp in said first registration message;
if said time stamp in said second registration message does not equal said time stamp in said first registration message, computing an age of said second registration message based on said time stamp in said first registration message;
and
accepting said second registration message if said age of said second registration message is less than a verification threshold.

6 more elements

Dependencies are inferred from the claim text.

Method for time stamp-based replay protection and PDSN synchronization at a PCF

Life of this patent

Method for time stamp-based replay protection and PDSN synchronization at a PCF

Life of this patent

Abstract

Claims31