International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064 Index Copernicus Value (2013): 6.14 | Impact Factor (2015): 6.391 Volume 5 Issue 4, April 2016 www.ijsr.net Licensed Under Creative Commons Attribution CC BY A Survey on Anonymous User Authentication using Decentralized Key Distribution Architecture Purva Chavan 1 , Prof. B. P. Vasgi 2 1, 2 Sinhgad College of Engineering, Pune, Maharashtra, India Abstract: One of the powerful features of Cloud Computing is storing data at the third party site without the hassles of maintenance, storage space, etc. Decentralized access control scheme can be used for securely storing data onto clouds. The scheme enables anonymous authentication of users by hiding user’s details from the cloud before storing the data. The access control scheme enables the owner of data to grant read and write access only to those who satisfy certain attributes specified by the owner and thus are the valid users. It supports decentralized architecture which prevents single point of failure and workload on a single system. The scheme is thus robust. Also it supports user revocation to prevent stale entry of data. Keywords: access control, authentication, key distribution center, attribute based encryption, cloud storage 1. Introduction Cloud computing provides anywhere anytime ubiquitous service using the internet which has made it popular in today’s technology oriented world. One of the powerful features of cloud is enormous storage at third party site. It frees the users from the overhead of maintaining resources on site and also services are provided at lower costs whenever needed. Cloud provides the facility of storing innumerous amount of data along with easy access. But this comes with concerns like privacy and security because much of the data stored in cloud contains highly sensitive information like medical records and social networks. Thus, proper techniques need to be implemented to safeguard the outsourced data. Major Headings 1.1. User Privacy and Data Security User Privacy refers to keeping the identity of users confidential. There are situations where a user who created the data wants to remain anonymous. Example: Bob is a law student and wants to send a series of reports about malpractices being carried out by the authorities of some university X to all the chairpersons, professors, students of that university. He wants to remain anonymous while publishing all evidences. All the information is stored in cloud. Here it is important the identity of Bob should not be revealed to others. For this purpose a claim message is also need to be sent which guarantees that message came from a valid source[10]. Data security is commonly referred to as the confidentiality, availability, and integrity of data. It is the practice of ensuring that the data is safe from unauthorized access and use, ensuring that the data is reliable and accurate and is available for use whenever it is needed[10]. 2. Related Work In the year 1992, D.F. Ferraiolo and D. R. Kuhn gave the concept of Role-Based access control where the user holding certain role was only allowed to access stored data. This scheme did not give fine grained access control. More powerful schemes were derived later. In the distributed systems users should be able to access the data only if a user possesses certain set of attributes. Attribute-Based encryption for fine grained access control of encrypted data was the scheme proposed by V. Goyal, O. Pandey A. Sahai, B. Waters in the year 2006[1]. User satisfying the attributes was only able to access the data. Access policy containing set of attributes was defined which defines the kind of users having access to data. Key Policy based schemes allowed for the policy as part of the key and ciphertexts carry attributes. Ciphertext Policy attribute based encryption concept given by Z. Liu, Z. Cao, Duncan S. Wong[2] embeds the policy or circuit as to who can decrypt the data as part of the ciphertext. In 2013, sauthors Ming li, Shucheng Yu[8] came up with the concept of securely maintaining Personal Health Records at the third party site. The PHR service allowed the patient to create and manage their medical history in one place by means of web. The data stored was encrypted first before outsourcing it onto semi-trusted cloud. In 2014, Decentralized access control architecture with anonymous authentication concept was laid by S. Ruj, M. Stojmenovic amd A. Nayak[10]. The scheme is robust, secure and hides the identity of owner of the data. Keys are distributed in a decentralized fashion, thus avoids single point of failure which means there can be several KDC’s (Key Distribution Center) for key management. Only users with valid set of attributes are able to access data stored on cloud. User whose access rights have been revoked cannot enter data on cloud. Thus, preventing stale data entry in the storage environment and is resilient to replay attacks. Unlike previous scheme, it supports multiple reads and writes. Information is at major risk at the third party site. Recent years have seen much technological advancement in the field of security for data stored in cloud. Continuous efforts have led to some secure mechanisms like Attribute Based encryption, use of Key Management Centers for the Paper ID: NOV162191 724