1. LYU9905 Security in Mobile Agent E-Commerce Systems Prepared by : Wong Ka Ming, Caris Wong Tsz Yeung, Ah Mole Supervisor :LYU Rung Tsong Michael Date : 7/12/99

2. LYU9905 Security in Mobile Agent E-Commerce Systems2 Outline Introduction What is Mobile Agent Overview of SIAS - Shopping Information Agent System Security in Mobile Agent System & Cryptography Security Attacks and Defenses Scenarios in SIAS Future Work Q & A Session

3. LYU9905 Security in Mobile Agent E-Commerce Systems3 Introduction (1) Mobile software agents has become an important aspect in the electronic commerce Electronic commerce and information retrieval are two prospective directions for application of mobile agents Security is a crucial concern for such system

4. LYU9905 Security in Mobile Agent E-Commerce Systems4 Introduction (2) Discuss mobile agents properties and capability Describe the system we have build for the FYP – Shopping Information Agent System (SIAS) Discuss the security problems for the mobile agents Particularly, analyze possible security attacks by malicious hosts against agents in SIAS Last but not least, our solutions to detect these attacks

5. LYU9905 Security in Mobile Agent E-Commerce Systems5 What is Mobile Agent (1) Agent Definition - (User Perspective) An Agent is a program that assists people and acts on their behalf. Agents function by allowing people to delegate work to them Example : Stock Broker

6. LYU9905 Security in Mobile Agent E-Commerce Systems6 What is Mobile Agent (2) Agent Definition - (System Perspective) An agent is a software object that is situated within an execution environment able to communicate with other agents mobile and able to travel from one host to another Autonomous, has control over its own actions

7. LYU9905 Security in Mobile Agent E-Commerce Systems7 What is Mobile Agent (3) Dispatch, Disconnect, and Dispatch model

8. LYU9905 Security in Mobile Agent E-Commerce Systems8 What is Mobile Agent (4) Advantages of mobile agent over Client/Server Paradigms Reduce the network load Overcome network latency Execute asynchronously and autonomously Adapt to changes dynamically Robust and fault-tolerant

9. LYU9905 Security in Mobile Agent E-Commerce Systems9 Mobile Agent Products Aglets from IBM Concordia from Mitsubishi Voyager from ObjectSpace

10. LYU9905 Security in Mobile Agent E-Commerce Systems10 Introducing SIAS (1) SIAS - Shopping Information Agent System SIAS is a web-based e-commerce mobile agent system It provides users with information of products for sale in an electronic marketplace It is written in Java programming language and on top of the Concordia API, which is developed by Mitsubishi Electric Research Lab

11. LYU9905 Security in Mobile Agent E-Commerce Systems11 Introducing SIAS (2) An electronic market consists of hosts that sell products on the network Each seller maintains a database that stores the prices and quantities in stock of different products available at that host It allows users to specify a set of products and quantities

12. LYU9905 Security in Mobile Agent E-Commerce Systems12 Introducing SIAS (3) An agent is created for an user whenever he/she has specified a list of products and quantities After the agent has visited all hosts specified in its itinerary, it returns to its sender and reports the lowest prices and corresponding sellers The agent starts travelling in the network according to its itinerary (path), which is pre-determined while it is created

13. LYU9905 Security in Mobile Agent E-Commerce Systems13 Introducing SIAS (4) Simplified model for SIAS

14. LYU9905 Security in Mobile Agent E-Commerce Systems14 SIAS Details - Implementation (1) Four main objects in the system Agent - retrieves product information from hosts for users Launch Server - it is a gateway between agent system and client programs. It initializes and launches an agent whenever it receives requests from clients. It is also used for receiving agents when an agents finishes its trips

15. LYU9905 Security in Mobile Agent E-Commerce Systems15 SIAS Details - Implementation (2) Database Server - Client Program - it is used for retrieving information from its own database. It also receives incoming agents and provides execution environments for them until they finish executions and leave It is a Java Applet which lets users to choose products and quantities. Each instance of the client program can communicate with the Launch Server

16. LYU9905 Security in Mobile Agent E-Commerce Systems16 SIAS Details - Implementation (3) Our current SIAS design : One Launch Server - it is a trusted host. Three Data Base Servers - some of them may be malicious Client is using Netscape Communicator 4.5

17. LYU9905 Security in Mobile Agent E-Commerce Systems17 SIAS Details - Implementation (4) Data Base Server 1 Launch Server Client requestReport results to client Data Base Server 2 Data Base Server 3 A new agent is createdThe agent is launched and starts to travel Agent is going to Data Base Server 1 Agent arrives at Data Base Server 1 Agent retrieves data from database and leaves Agent is going to Data Base Server 2 Agent arrives at Data Base Server 2 Agent retrieves data from database and leaves Agent is going Data Base Server 3 Agent arrives at Data Base Server 3 Agent retrieves data from database and leaves Agent is going back to Launch Server Agent calculates the cheapest purchasing combination and it will be destroyed by the Launch Server

18. LYU9905 Security in Mobile Agent E-Commerce Systems18 SIAS Details - Implementation (5) Technology used in Agent object Agent - it is a Concordia object It enables an object which is a subclass of Concordia Agent to dispatch (marshalling) itself into the network and retract (unmarshalling) into another host

19. LYU9905 Security in Mobile Agent E-Commerce Systems19 SIAS Details - Implementation (6) Data Base Server - the Data Base Server uses an object namely Agent Transporter to receive and send agents. Agent Transporter is able to control every execution of a received agent. The database server used is Oracle 8i. Oracle provides a driver for JDBC, which is a Java Solution for Database Connectivity Technology used in Data Base Server object

20. LYU9905 Security in Mobile Agent E-Commerce Systems20 SIAS Details - Implementation (7) Technology used in Launch Server object It also uses Agent Transporter to receive and send agents It uses RMI (Remote Method Invocation) to connect with clients Why RMI but not Agent?? Concordia Problem - client needs to install the Concordia API in order to send and receive agents by web browser Not convenient to use, so choose RMI.

21. LYU9905 Security in Mobile Agent E-Commerce Systems21 SIAS Details - Implementation (8) Technology used in client program It is a Java Applet It uses RMI to connect to Launch Server Can I have a look on it ?? Yes, you canYes, you can

22. LYU9905 Security in Mobile Agent E-Commerce Systems22 SIAS Details - Implementation (9)

23. LYU9905 Security in Mobile Agent E-Commerce Systems23 Security in Mobile Agent (1) Security problems of malicious agents against hosts Trojan horse attacks by malicious agents This can be effectively solved by strong authentication of the code sources verification of code integrity limiting the access rights of incoming agents to local resources of hosts

24. LYU9905 Security in Mobile Agent E-Commerce Systems24 Security in Mobile Agent (2) Security problems of malicious agents against hosts When an agent executes on a remote host, the host is likely to have access to all the data and code carried by the agent If a host is malicious and abuses the code or data, the privacy and secrecy of the agent and its owner would be at risk

25. LYU9905 Security in Mobile Agent E-Commerce Systems25 Security in Mobile Agent (2) Seven types of attacks by malicious hosts Spying out and manipulation of code Spying out and manipulation of data Spying out and manipulation of control flow Incorrect execution of code Masquerading of the host Spying out and manipulation of interaction with other agents Returning wrong results of system calls to agents

26. LYU9905 Security in Mobile Agent E-Commerce Systems26 Security in Mobile Agent (3) In SIAS, we have chosen a technique called Agent Tempering Detection Agent Tempering Detection: hiding from hosts the data possessed by agents and the function to be computed by agents by messing up code and data of agents, or using cryptographic technique We will discuss: Asymmetric Cryptography & Digital Signature

27. LYU9905 Security in Mobile Agent E-Commerce Systems27 Asymmetric Cryptography (1) The main difference between asymmetric & traditional cryptography is the introduction of public key and private key Public key & private key are generated in pairs The message is then encrypted, transmitted and decrypted at the other end, without the need to pass around the private key, which put the private key under risks of exposure to the public

28. LYU9905 Security in Mobile Agent E-Commerce Systems28 Asymmetric Cryptography (2) Digital Signature is used to verify the entity that has been signed A person who send a message can append an encrypted form of the message, using sender’s private key, to the end of the message. The receiver of the message can decrypt the append cipher-text using the sender’s public key, and verify the integrity of the received message. The appended cipher-text served as a digital signature of the sender for the sent message

29. LYU9905 Security in Mobile Agent E-Commerce Systems29 RSA Algorithm R.L. Rivest, A. Shamir, and L. Adelman proposed their well-known RSA encryption algorithm. In the RSA scheme, a message M is encrypted with the encryption key e by the function: Cipher-text = E(M,e,N) = M e mod N Message = D(C,d,N) = C d mod N The pair (e,N) is distributed as the public key while d is kept private. It can be proved that given d and e are carefully selected such that: – d x e = 1 mod (p-1)(q-1) and d is relatively prime to (p-1)(q-1), the functions D and E are the inverse of each other.

30. LYU9905 Security in Mobile Agent E-Commerce Systems30 RSA: An Example Pick p = 5, q = 7, z = 24, n = 35 Choose d = 5, relatively prime to z 1 mod z = 1, 25, 49, 73, 97, 121, 145... Pick e = 145 / d = 29 Public key (35, 29); Private key (35, 5) Encrypting message M = 10: E(M) = 10 29 mod 35 = 5 VERIFY: Decrypting cipher-text c = 5: D(c) = 5 5 mod 35 = 3125 mod 35 = 10 = M In practice, much larger primes p, q are used The security provided by RSA relies on the fact that it is computationally infeasible to factor a large number n to find out p, q, and hence z, e

31. LYU9905 Security in Mobile Agent E-Commerce Systems31 Attacks and Defenses on SIAS (1) Scenario 1 - Modification of query products The list of products specified by user is stored as plain text Malicious host can easily spy out the data and change it Later hosts will response to such changes, and report wrong information This violates the integrity of queries

32. LYU9905 Security in Mobile Agent E-Commerce Systems32 Attacks and Defenses on SIAS (2) Scenario 2 - Modification of query quantities Similar to scenario 1 This lead the later host to report wrong information

33. LYU9905 Security in Mobile Agent E-Commerce Systems33 Attacks and Defenses on SIAS (3) Scenario 3 - Spying out and modification of query results Agents carry query results in plain text Malicious hosts can spy out and modify the results that the agent has collected from previous hosts Such changes can favor the malicious hosts For example, a malicious host raises all the prices reported from previous hosts.

34. LYU9905 Security in Mobile Agent E-Commerce Systems34 Attacks and Defenses on SIAS (4) Scenario 4 - Modification of itinerary of agent Itinerary of an agent is accessible to hosts Malicious hosts can change the itinerary of an agent Agents may go to hosts that are not specified in itinerary Agents may skip hosts that are specified in itinerary

35. LYU9905 Security in Mobile Agent E-Commerce Systems35 Attacks and Defenses on SIAS (5) Hybrid Attacks Can mix the above 4 attacks

36. LYU9905 Security in Mobile Agent E-Commerce Systems36 Attacks and Defenses on SIAS (6) Solution to Attack Scenario 1 & 2 We introduce digital signature on the whole list of product IDs as well as the signature on the list of product quantities {Product ID list} => {Product ID list}sig A ({Product ID list}) {Quantity list} =>{Quantity list}sig A ({Quantity list})

37. LYU9905 Security in Mobile Agent E-Commerce Systems37 Attacks and Defenses on SIAS (7) Solution to Attack Scenario 3 We introduce RSA encryption algorithm on the results obtained from the Data Base server {Query result} => D A ({Query result}sig H ({Query result}))

38. LYU9905 Security in Mobile Agent E-Commerce Systems38 Attacks and Defenses on SIAS (8) Solution to Attack Scenario 4 The Data Base server will sign the path of the agent to ensure the agent goes the right path E HN (E H(N-1) (…E H2 (E H1 (Itinerary at Host 1) Itinerary at Host 2) … Itinerary at Host N-1) Itinerary at Host N)

39. LYU9905 Security in Mobile Agent E-Commerce Systems39 Attacks and Defenses on SIAS (9) Introduce 2 new objects to support security measures RSA object ; and Key Server object

40. LYU9905 Security in Mobile Agent E-Commerce Systems40 Attacks and Defenses on SIAS (10) RSA object is the core of Secure SIAS design It helps to implement a public key infrastructure (PKI) It can encrypt a character string to ciphertext, and decrypt a ciphertext to a character string

41. LYU9905 Security in Mobile Agent E-Commerce Systems41 Attacks and Defenses on SIAS (11) Key Server object acts as a Certificate Authority (CA) of our PKI It accepts public keys from agents and hosts, and distribute them It uses RMI in transporting public keys Why not agent but RMI?? Endless chain of security measures

42. LYU9905 Security in Mobile Agent E-Commerce Systems42 Attacks and Defenses on SIAS (12) A Secure SIAS

43. LYU9905 Security in Mobile Agent E-Commerce Systems43 Security Analysis on SIAS (1) We have test times for SIAS to launch a single agent before and after the implementation of the security mechanisms. Round trip times (RTTs) required for an agent to travel around are measured. Queries of different sizes have been tested.

44. LYU9905 Security in Mobile Agent E-Commerce Systems44 Security Analysis on SIAS (2) Figure shows SIAS without security measures and attacks The RTT increases very slightly Overhead by each additional item in average is about 18.9 milliseconds. This can be explained by the small change in delay of database query with different query sizes.

45. LYU9905 Security in Mobile Agent E-Commerce Systems45 Security Analysis on SIAS (3) Figure shows SIAS with security measures implemented The RTT increases very fast and linearly with the size of query The overhead of each additional item is about 245 milliseconds, 13 times the overhead of the primary SIAS design This can be explained by the use of RSA algorithm It is time consuming to encrypt and decrypt data with long keys. Trade-off between performance and security for SIAS.

46. LYU9905 Security in Mobile Agent E-Commerce Systems46 Security Analysis on SIAS (4) This graph and the next show SIAS with the simulation of malicious host’s attacks Both shows an agent takes more time to travel then the first figure. This suggests that the RTT may be used as a measure for tempering detection Figure shows SIAS with simulation of attacks - modification of product IDs

47. LYU9905 Security in Mobile Agent E-Commerce Systems47 Security Analysis on SIAS (5) Figure shows SIAS with simulation of attacks - modifying itinerary

48. LYU9905 Security in Mobile Agent E-Commerce Systems48 Summary We studied the technology of autonomous mobile agents and discussed the problem of malicious hosts in a mobile agent system. We implemented SIAS as a sample application of mobile agents, which reduces communication cost and allows delegation of tasks. We addressed some security problems of malicious hosts in SIAS, and developed a primitive approach to protect the agents. We analyzed the security of our approach, and believe it is strong enough for domestic purpose. We measured the performance overhead of the security measures, see a trade-off between performance and security for SIAS, and learned that it takes time for a malicious host to attack an agent.

49. LYU9905 Security in Mobile Agent E-Commerce Systems49 Future Work We will implement payment method on SIAS We will scale up the current system We will continue to think of other security attack scenarios and corresponding solutions (such as multiple malicious hosts) We believe autonomous mobile agents would be an important technology in future distributed systems.

50. LYU9905 Security in Mobile Agent E-Commerce Systems50 END THANK YOU!!