Biblio

With the widespread application of distributed information processing, information processing security issues have become one of the important research topics; CAPTCHA technology is often used as the first security barrier for distributed information processing and it prevents the client malicious programs to attack the server. The experiment proves that the existing “request / response” mode of CAPTCHA has great security risks. “The text-based CAPTCHA solution without network flow consumption” proposed in this paper avoids the “request / response” mode and the verification logic of the text-based CAPTCHA is migrated to the client in this solution, which fundamentally cuts off the client's attack facing to the server during the verification of the CAPTCHA and it is a high-security text-based CAPTCHA solution without network flow consumption.

Security is playing a very important and crucial role in the field of network communication system and Internet. Kerberos Authentication Protocol is designed and developed by Massachusetts Institute of Technology (MIT) and it provides authentication by encrypting information and allow clients to access servers in a secure manner. This paper describes the design and implementation of Kerberos using Data Encryption Standard (DES). Data encryption standard (DES) is a private key cryptography system that provides the security in the communication system. Java Development Tool Kit as the front end and ms access as the back end are used for implementation.

MANET is an infrastructure less, dynamic, decentralised network. Any node can join the network and leave the network at any point of time. Due to its simplicity and flexibility, it is widely used in military communication, emergency communication, academic purpose and mobile conferencing. In MANET there no infrastructure hence each node acts as a host and router. They are connected to each other by Peer-to-peer network. Decentralised means there is nothing like client and server. Each and every node is acted like a client and a server. Due to the dynamic nature of mobile Ad-HOC network it is more vulnerable to attack. Since any node can join or leave the network without any permission the security issues are more challenging than other type of network. One of the major security problems in ad hoc networks called the black hole problem. It occurs when a malicious node referred as black hole joins the network. The black hole conducts its malicious behavior during the process of route discovery. For any received RREQ, the black hole claims having route and propagates a faked RREP. The source node responds to these faked RREPs and sends its data through the received routes once the data is received by the black hole; it is dropped instead of being sent to the desired destination. This paper discusses some of the techniques put forwarded by researchers to detect and prevent Black hole attack in MANET using AODV protocol and based on their flaws a new methodology also have been proposed.