Mshangi, Maduhu2020-05-222020-05-222019Mshangi, M (2019) Homomorphic cryptography techniques-based algorithm for enhanced privacy of users’ data in social network systems in Ubiquitous computing.Master dissertation, University of Dar es Salaam, Dar es Salaam.http://41.86.178.5:8080/xmlui/handle/123456789/11433Available in printed form, East Africana Collection, Dr. Wilbert Chagula Library, Class mark (THS EAF QA150.T34M832)The use of social network systems (SNS) for interaction and sharing of information across the globe has led to new vulnerabilities and cyber threats. This has resulted in privacy violation of users’ data in SNS such as Facebook, Twitter, LinkedIn and Instagram. Privacy violation of users’ data is the problematic situation in which many researchers are trying to address. The study adopted soft systems methodology compounded with design science research to guide the research process. The research methods used include heuristic evaluation inspection experiment and divide and conquer. The study assessed the effectiveness and efficiency of the existing privacy controls in SNS to ascertain the research gap status quo. It revealed that the existing privacy controls in the SNS are not adequate in addressing privacy violation in SNS. The study proposes an algorithm for enhancing the privacy of users’ data in SNS based on homomorphic cryptography techniques. The performance analysis of the proposed algorithm was carried out using Big O notation and controlled experiment. The study found that the proposed algorithm has a time complexity of and execution time of shorter than 0.094 seconds for keys size of at most 1024 bit. It was compared with other related algorithms in a similar environment; their execution times were found to be more than 0.116 seconds. Thus, the proposed solution can be adopted to enhance the privacy of users’ data in SNS. It can be extended to other services accessible via untrusted environments.enAlgorithmsAlgebraSocial networkCryptographyThesis