A Fast Data Protection Technique for

Mobile Agents to Avoid Attacks in Malicious Hosts

Jesús Arturo Pérez DíazDarío Álvarez Gutiérrez

Department of Informatics University of Oviedo

Oviedo, Asturias, Spain

Presenter: Chin-chi Lo

Outline

A Secure Mobile Agent SystemTraditional TechniquesEncryption Algorithm using Bitmaps & XORLimitations & Conclusion

A Secure Mobile Agent System

Protection of the agent system against attacks from mobile agents.Protection of the agent against agents.Protection of information transmission between agent servers against unauthorized third parties.Protection of the agent against malicious agent systems.

Traditional Techniques

Public key cryptographyDigital SignaturesImplementing Secure Channel Ex: SSL, TLS

All of the above are too complex and almost unfeasible in terms of performance.

Data Encryption using Bitmaps & the XOR Operation

BitmapsA random number expressed as a

bitmap in a row of a matrix carried by an agent and known only to the source server.

XORApplying XOR operation between data

and a random number.

Data Area of the Mobile Agent

Fields

HostID: identifier of a server.

CW: “codeword”, used to rotate the data before applying the encryption function.

CRC: verifying if the data is altered. The initial value is binary 0’s.

Encryption Algorithm

1. The remote server creates a record with the same fields.

2. The host ID, data to be encrypted in 128-bit blocks form and a generated random CW are put into the record.

3. is rotated to the left ,where

ri

ri

ri lff

FhCWl ri 07&

rif

Encryption Algorithm (Cont.)

4. Before applying the (3.), the CW is rotated to the right.(7 most-significant bits of CW)

Thus, each is not always the same.

FhCWmmCWCW ri

ri 07&7,

ril

Encryption Algorithm (Cont.)

5. The original CW is restored into the corresponding field of the register in order to retrieve the original information using the inverse algorithm in the source server.

6. Computing CRC.7. The corresponding original bitmap is

XOR’ed with generated data.8. The counter indicating the number of

lines used in the matrix is incremented.

Limitations of the Method

Does not prevent the possible alternation of data from malicious hostsThe current server could see and copy the still available rows .The two cooperating malicious servers.There is a fixed maximum number of data that can be protected.

Conclusion

That is a trade-off between performance and security.