LYU 9905 Security in Mobile Agent ECommerce Systems
LYU 9905 Security in Mobile Agent E-Commerce Systems Prepared by : Supervisor : Wong Ka Ming, Caris Wong Tsz Yeung, Ah Mole LYU Rung Tsong Michael Date : 7/12/99 LYU 9905 Security in Mobile Agent E-Commerce Systems
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 2
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 3
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 4
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 5
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 6
What is Mobile Agent (3) • Dispatch, Disconnect, and Dispatch model LYU 9905 Security in Mobile Agent E-Commerce Systems 7
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 8
Mobile Agent Products • Aglets from IBM • Concordia from Mitsubishi • Voyager from Object. Space LYU 9905 Security in Mobile Agent E-Commerce Systems 9
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 10
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 11
Introducing SIAS (3) • An agent is created for an user whenever he/she has specified a list of products and quantities • The agent starts travelling in the network according to its itinerary (path), which is pre-determined while it is created • After the agent has visited all hosts specified in its itinerary, it returns to its sender and reports the lowest prices and corresponding sellers LYU 9905 Security in Mobile Agent E-Commerce Systems 12
Introducing SIAS (4) • Simplified model for SIAS LYU 9905 Security in Mobile Agent E-Commerce Systems 13
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 14
SIAS Details - Implementation (2) • Database Server • 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 • Client Program • 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 LYU 9905 Security in Mobile Agent E-Commerce Systems 15
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 16
SIAS Details - Implementation (4) Data Base Server 1 Data Base Server 2 Data Base Server 3 Launch Server Client request Report results to client Agent calculates theto cheapest A new The agent is launched is created Data Base Agent arrives retrieves is going atback Data data Data Base to from Base purchasing combination and it will and starts Base Server to 1 travel 2 leaves Server database Launch 32 Server and be destroyed by the Launch Server LYU 9905 Security in Mobile Agent E-Commerce Systems 17
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 18
SIAS Details - Implementation (6) • Technology used in Data Base Server object • 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 8 i. Oracle provides a driver for JDBC, which is a Java Solution for Database Connectivity LYU 9905 Security in Mobile Agent E-Commerce Systems 19
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. LYU 9905 Security in Mobile Agent E-Commerce Systems 20
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 can LYU 9905 Security in Mobile Agent E-Commerce Systems 21
SIAS Details - Implementation (9) LYU 9905 Security in Mobile Agent E-Commerce Systems 22
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 23
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 24
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 25
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 26
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 27
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 28
RSA Algorithm l l l 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) = Me mod N Message = D(C, d, N) = Cd 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. LYU 9905 Security in Mobile Agent E-Commerce Systems 29
RSA: An Example l l l l l 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) = 1029 mod 35 = 5 VERIFY: Decrypting cipher-text c = 5: D(c) = 55 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 LYU 9905 Security in Mobile Agent E-Commerce Systems 30
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 31
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 32
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. LYU 9905 Security in Mobile Agent E-Commerce Systems 33
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 34
Attacks and Defenses on SIAS (5) • Hybrid Attacks • Can mix the above 4 attacks LYU 9905 Security in Mobile Agent E-Commerce Systems 35
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}) LYU 9905 Security in Mobile Agent E-Commerce Systems 36
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} => DA({Query result}sig. H({Query result})) LYU 9905 Security in Mobile Agent E-Commerce Systems 37
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 • EHN(EH(N-1)(…EH 2(EH 1(Itinerary at Host 1) Itinerary at Host 2) … Itinerary at Host N-1) Itinerary at Host N) LYU 9905 Security in Mobile Agent E-Commerce Systems 38
Attacks and Defenses on SIAS (9) • Introduce 2 new objects to support security measures • RSA object ; and • Key Server object LYU 9905 Security in Mobile Agent E-Commerce Systems 39
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 40
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 41
Attacks and Defenses on SIAS (12) • A Secure SIAS LYU 9905 Security in Mobile Agent E-Commerce Systems 42
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. l Round trip times (RTTs) required for an agent to travel around are measured. l Queries of different sizes have been tested. l LYU 9905 Security in Mobile Agent E-Commerce Systems 43
Security Analysis on SIAS (2) • 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. Figure shows SIAS without security measures and attacks LYU 9905 Security in Mobile Agent E-Commerce Systems 44
Security Analysis on SIAS (3) • 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. Figure shows SIAS with security measures implemented • Trade-off between performance and security for SIAS. LYU 9905 Security in Mobile Agent E-Commerce Systems 45
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 LYU 9905 Security in Mobile Agent E-Commerce Systems 46
Security Analysis on SIAS (5) Figure shows SIAS with simulation of attacks modifying itinerary LYU 9905 Security in Mobile Agent E-Commerce Systems 47
Summary l We studied the technology of autonomous mobile agents and discussed the problem of malicious hosts in a mobile agent system. l We implemented SIAS as a sample application of mobile agents, which reduces communication cost and allows delegation of tasks. l We addressed some security problems of malicious hosts in SIAS, and developed a primitive approach to protect the agents. l We analyzed the security of our approach, and believe it is strong enough for domestic purpose. l 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. LYU 9905 Security in Mobile Agent E-Commerce Systems 48
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. LYU 9905 Security in Mobile Agent E-Commerce Systems 49
END THANK YOU!! LYU 9905 Security in Mobile Agent E-Commerce Systems 50
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