Secure Data Exchange System : Minimizing Security Attacks Risks Whi... http://www.cse.wustl.edu/~jain/cse571-07/ftp/dataexch/1 of 17 12/19/2007 5:11 PMSecure Data Exchange System : Minimizing SecurityAttack Risks while Preserving BandwidthAbdel-karim Al [email protected] [email protected] the world where Internet applications dominate data communications, a system to exchange information securelybetween Internet users is vital. Many solutions have been put forward to facilitate such exchange, these solutionshave their own advantages and disadvantages. In this paper we introduce a thin secure layer that resides on top ofthe IP layer and supports encryption and compression of IP packets. Our solution provides the necessary securitylevel to overcome most of the security risks without sacrificing performance and network bandwidth. By giving theoption to choose between different levels of encryption and compression levels, the users can choose the level mostsuitable to their needs. In order to show the usage of our security layer, we implemented a simple chatting systemthat’s capable of exchanging encrypted text messages and allows the clients to send encrypted and compressed files.The application also provides two ways to sniff network traffic showing the risks of exchanging informationwithout imposing a proper security level.Keywords:Security Protocol, IPSec, Encryption, Rijndael, Compression, Bandwidth Consumption, Session Management,Cryptography, IP Layer, TCP/IP Suite.See Also: IP Security : A Brief Survey Security in Wireless Data Networks : A Survey PaperTable of Contents:1. Introduction2. Related Solutions 2.1 IPSec 2.2 SSL3. System Design 3.1 System Objectives 3.2 Design Choices4. Software Design 4.1 Raw Socket 4.2 CryptZip Library5. Application Walkthrough6. Conclusion7. References8. Appendix A: AbbreviationsSecure Data Exchange System : Minimizing Security Attacks Risks Whi... http://www.cse.wustl.edu/~jain/cse571-07/ftp/dataexch/2 of 17 12/19/2007 5:11 PMBack to Table of Contents1. IntroductionThe Internet has replaced many traditional communication systems because of its advantages in both its cost andusability. Using the Internet to share information on daily basis puts users in risk to be endangered by many Internetsecurity attacks. Most of the data and money exchange is done these days using one of the many services providedto the users online. Such convenience comes with a high price where these communications are not alwaysefficiently secure.With the vast introduction of the wireless world, the exchanged information now is more prone to security risk thanever. One of the several security attacks is data sniffing, where the transmitted data is exposed to a third party andall the exchanged data is compromised. There are even commercial products that help network administrators orothers to view, store and analyze exchanged data packets[EffeTech06].The other common security attack is DoS (Denial of Service) attack, where the attacker overwhelms the victim’shost with many resource requests. A more severe version of this attack is DDoS (Distributed DoS), where theattacker uses more than one host to attack the victim’s host.Many solutions provide the mechanism of encrypting the ongoing data exchange packets between two peers. Evenwhen the packets are encrypted, the users are still prone to another security attack: Replay attack. Where theattacker uses pre-validated packets and sends them to one of the users to confuse and disrupt the communication.In this project we introduce a simple to implement and easy to use infrastructure that can provide the necessarysecurity level to exchange information between two nodes without the fear of being exposed to the sniffing attack.We also provide the necessary application level support to prevent replay attack. Because of the system's intendedsimplicity, it does not cover all the security risks out there. It does however, provide a base to overcome thesehazards in the future.This project report is divided into 6 sections: sections 1 and 2 cover the relevant and current solutions such as IPSec(IP Security) and SSL (Secure Socket Layer). Section 3 describes the system infrastructure, objectives, and designchoices. Section 4 provides an overview of the software structure of the system. Section 5, provides a walk-throughfor the basic chat system introduced and the current status of the project. Finally, section 6 provides a summary andconclusion of the project.Back to Table of Contents2. Related SolutionsThis section will illustrate two of the common solutions to facilitate exchanging data between users: IPSec and SSL.While IPSec operates on top of the IP layer, SSL operates on top of the TCP layer.2.1 IPSecIPSec is short for Internet Protocol Security and was developed by the IETF (Internet Engineering Task Force) toenable secure exchange of packets using the IP layer (layer 3). It is widely used in secure VPN (Virtual PrivateNetwork) communication. IPSec can work on two different encryption modes[WikiIPSec07]1. Transport ModeSecure Data Exchange System : Minimizing Security Attacks Risks Whi... http://www.cse.wustl.edu/~jain/cse571-07/ftp/dataexch/3 of 17 12/19/2007 5:11 PMThis mode only encrypts the payload (data) portion of the packet leaving the header unencrypted. Thismode is mostly used in host-host communications.2. Tunnel ModeThis mode the entire packet is encrypted and/or authenticated including the header. Which implies thatanother header has to be added to allow routing to work. This mode is used mainly in router-routercommunications. IPSec provides two methods of securing the IP packet using one of the two protocols:1. Authentication Header (AH)This protocol provides integrity and data origin authentication. It can also protect against replay attacks,repeating or delaying a previously valid packet, by using the sliding window technique. AH protectsthe IP header except for the mutable fields that have to change during transmission from source todestination such as the TTL field.2. Encapsulating Security Payload (ESP)This protocol ensures confidentiality, data origin authentication, connectionless integrity andanti-replay service. Unlike AH, ESP doesn’t protect the IP header in any way but this can be protectedby using the Tunnel Mode to protect the inner IP packet but the packet header will remain unprotected.In order for IPSec to operate properly, both the sender and