Detection of encrypted packet streams

• US 20060064579A1
• Filed: 09/17/2004
• Published: 03/23/2006
• Est. Priority Date: 09/17/2004
• Status: Active Grant

• Current Assignee: Bellsouth Intellectual Property Corporation (AT&T, Inc.)
• Original Assignee: Bellsouth Intellectual Property Corporation (AT&T, Inc.)
• Inventors: Aaron, Jeffrey A., Shrum, Edgar Vaughan Jr.
• Granted Patent: US 7,761,705 B2
• Time in Patent Office: Days
• US Class Current: 713/150
• CPC Class Codes: H04L 63/04 for providing a confidential data exchange among entities communicating through data packet networks

Abstract

Methods, systems, and products are disclosed for detecting encrypted packet streams. One method notes an observable parameter of an encrypted stream of packets. The parameter is observable despite encryption obscuring the contents of the encrypted stream of packets. The type of data within the encrypted stream of packets is inferred from the observable parameter, wherein, despite the encryption, the type of data within the encrypted stream of packets may be inferred.

Claims

1. A method, comprising the steps of:

noting an observable parameter of an encrypted stream of packets, the parameter being observable despite encryption obscuring the contents of the encrypted stream of packets; and

inferring the type of data within the encrypted stream of packets from the observable parameter,

wherein, despite the encryption, the type of data within the encrypted stream of packets may be inferred.

2. A method according to claim 1, wherein the step of noting the observable parameter comprises at least one of i) measuring a size of an encrypted packet, ii) measuring a timing interval between encrypted packets, and iii) noting a pattern of packets.

3. A method according to claim 2, further comprising at least one of the steps of i) comparing to an expected packet size, ii) comparing to a minimum threshold packet size, iii) comparing to a maximum threshold packet size, and iv) comparing to a threshold range of packet sizes.

4. A method according to claim 3, further comprising at least one of the steps:

i) if the observable parameter equals the threshold, then inferring the type of data within the encrypted stream of packets;

ii) if the observable parameter exceeds the threshold, then inferring the type of data within the encrypted stream of packets; and

iii) if the observable parameter is less than the threshold, then declining to infer the type of data within the encrypted stream of packets.

5. A method according to claim 2, further comprising at least one of the steps of i) comparing to an expected timing interval, ii) comparing to a minimum threshold timing interval, iii) comparing to a maximum threshold timing interval, and iv) comparing to a threshold range of timing intervals.

6. A method according to claim 1, wherein the step of noting the observable parameter comprises at least one of i) computing an average timing interval within the encrypted stream of packets and ii) computing an average packet size within the encrypted stream of packets.

7. A method according to claim 1, wherein the encrypted stream of packets comprises Voice Over Internet Protocol data, and the step of inferring the type of data within the encrypted stream of packets comprises inferring the Voice Over Internet Protocol data from the observable parameter,

wherein, despite the encryption, the Voice Over Internet Protocol data within the encrypted stream of packets may be inferred.

8. A system, comprising:

a communications module stored in a memory device, and a processor communicating with the memory device;

the communications module noting an observable parameter of an encrypted stream of packets, the parameter being observable despite encryption obscuring the contents of the encrypted stream of packets, the communications module comparing the observable parameter to a threshold value, and the communications module inferring the type of data within the encrypted stream of packets from the observable parameter,

wherein, despite the encryption, the type of data within the encrypted stream of packets may be inferred.

9. A system according to claim 08, wherein the communications module performs at least one of the following steps:

i) measures a size of an encrypted packet,

ii) measures a timing interval between encrypted packets, and

iii) notes a pattern of packets.

10. A system according to claim 8, wherein the communications module compares the observable parameter to a threshold value.

11. A system according to claim 10, wherein the communications module performs at least one of the following steps:

i) if the observable parameter equals the threshold value, then the communications module infers the type of data within the encrypted stream of packets;

ii) if the observable parameter exceeds the threshold value, then the communications module infers the type of data within the encrypted stream of packets; and

iii) if the observable parameter is less than the threshold value, then the communications module declines to infer the type of data within the encrypted stream of packets.

12. A system according to claim 8, wherein the stream of packets comprises Internet Protocol packets.

13. A system according to claim 8, wherein the communications module performs at least one of the following steps:

i) computes an average timing interval within the encrypted stream of packets;

ii) computes an average packet size within the encrypted stream of packets; and

iii) if the encrypted stream of packets comprises Voice Over Internet Protocol data, then the communications module infers the Voice Over Internet Protocol data from the observable parameter, wherein, despite the encryption, the Voice Over Internet Protocol data within the encrypted stream of packets may be inferred.

14. A computer program product comprising a computer readable medium including instructions for performing the steps:

noting an observable parameter of an encrypted stream of packets, the parameter being observable despite encryption obscuring the contents of the encrypted stream of packets; and

inferring the type of data within the encrypted stream of packets from the observable parameter,

wherein, despite the encryption, the type of data within the encrypted stream of packets may be inferred.

15. A computer program product according to claim 14, wherein the instructions also perform at least one of the steps i) measuring a size of an encrypted packet, ii) measuring a timing interval between encrypted packets, and iii) noting a pattern of packets.

16. A computer program product according to claim 14, wherein the instructions also perform the step of comparing the observable parameter to a threshold value.

17. A computer program product according to claim 16, wherein the instructions also perform at least one of the steps:

i) if the observable parameter equals the threshold value, then inferring the type of data within the encrypted stream of packets;

ii) if the observable parameter exceeds the threshold value, then inferring the type of data within the encrypted stream of packets; and

iii) if the observable parameter is less than the threshold value, then declining to infer the type of data within the encrypted stream of packets.

18. A computer program product according to claim 14, wherein the stream of packets comprises Internet Protocol packets.

19. A computer program product according to claim 14, wherein the instructions also perform at least one of the steps:

i) computing an average timing interval within the encrypted stream of packets and ii) computing an average packet size within the encrypted stream of packets.

20. A computer program product according to claim 14, wherein if the encrypted stream of packets comprises Voice Over Internet Protocol data, then the instructions infer the Voice Over Internet Protocol data from the observable parameter,

wherein, despite the encryption, the Voice Over Internet Protocol data within the encrypted stream of packets may be inferred.