Packet flow side channel

• US 7,822,073 B2
• Filed: 11/03/2006
• Issued: 10/26/2010
• Est. Priority Date: 11/03/2005
• Status: Expired due to Fees

• Current Assignee: George Mason Intellectual Properties, Inc.
• Original Assignee: George Mason Intellectual Properties, Inc.
• Inventors: Wang, Xinyuan, Chen, Shiping, Jajodia, Sushil
• Primary Examiner(s): Pham; Chi H
• Assistant Examiner(s): Wong; Warner
• Application Number:
  US11/556,220
• Publication Number:
  US 20080080558A1
• Time in Patent Office: 1,453 Days
• Field of Search: 370/352, 370/385, 370/235, 370/461, 370/503, 370/529
• US Class Current: 370/516
• CPC Class Codes: H04L 65/70 Media network packetisation

Abstract

A packet flow side channel encoder and decoder embeds and extracts a side channel communication in an overt communication data stream transmitted over a network. The encoder selects more than one group of related packets being transmitted on the network, relates a packet of one group to a packet of another group to form a pair of packets; and delays the timing of at least one packet from each pair of packets The decoder determines inter-packet delays that are the difference in timing between two packets in a pair of packets; determines at least one inter-packet delay difference between two or more determined inter-packet delays; and extracts a bit using the at least one interpacket delay difference.

Claims

1. A system for embedding a covert side channel communication in an overt communication transmitted over a network using a packet stream, comprising:

a. an encoder configured to encode one or more bits of a side channel communication, the encoder including;

i. a packet group selection module configured to select at least two groups of related packets from the overt communication being transmitted on a network, each group of packets including a same number of packets;

ii. a packet relation module configured to relate a packet of one group to a packet of another group to form a pair of packets; and

iii. a packet delay module configured to delay the timing of at least one packet from each pair of packets; and

b. a decoder configured to decode the bits from the side channel communication, the decoder including;

i. an inter-packet delay determination module configured to determine the difference in timing between the two packets for each pair of packets;

ii. a difference determination module configured to determine at least one inter-packet delay difference between two or more determined inter-packet delays; and

iii. a bit extraction module configured to convert the at least one interpacket delay differences into a bit.

2. The system of claim 1, wherein the encoder uses an encoding algorithm.

3. The system of claim 1, wherein the decoder uses a decoding algorithm complementary to the encoding algorithm.

4. The system of claim 1, wherein the encoder and the decoder use a shared secret.

5. The system of claim 1, wherein the side channel communication includes a watermark.

6. The system of claim 1, wherein the overt communication includes a VoIP communication.

7. The system of claim 1, wherein the side channel communication identifies the overt communication.

8. The system of claim 1, wherein the encoder and the decoder are located on opposite sides of a router.

9. The system of claim 1, wherein bits are redundantly encoded.

10. A method for embedding a covert side channel communication in an overt communication transmitted over a network using a packet stream, comprising:

encoding one or more bits of a side channel communication by;

a. selecting more than one group of related packets from the overt communication being transmitted on a network, each group of packets including a same number of packets, the related packets being consecutive as well as non-consecutive packets;

b. relating a packet of one group to a packet of another group to form a pair of packets; and

c. delaying the timing of at least one packet from each pair of packets.

11. The method of claim 10, wherein the encoding uses an encoding algorithm.

12. The method of claim 10, wherein the selecting comprises selecting more than one group of packets in a random manner.

13. The method of claim 10, wherein the delaying comprises delaying the timing of the at least one packet without buffering the packets.

14. The method of claim 10, wherein the side channel communication includes a watermark.

15. The method of claim 10, wherein the overt communication includes a VoIP communication.

16. The method of claim 10, wherein the side channel communication identifies the overt communication.

17. A method for extracting a covert side channel communication in an overt communication transmitted over a network using a packet stream, comprising:

decoding a bit from the side channel communication by;

a. determining inter-packet delays that are the difference in timing between two packets in a pair of packets from the overt communication;

b. determining at least one inter-packet delay difference between two or more determined inter-packet delays; and

c. converting the at least one interpacket delay differences into a bit.

18. The method of claim 17, wherein the decoding uses a decoding algorithm.

19. The method of claim 17, wherein the overt communication includes redundantly encoded bits.

20. The method of claim 17, wherein the side channel communication identifies the overt communication.