## 4 Privacy Preserving in Cloud Computing
### Privacy Preservation through Access Patterns and Design  
Privacy Process Patterns are specifically designed to model privacy issues effectively. They can be defined as patterns applied to privacy associated processes by specifying how privacy issues can be realised through identifiable procedures, connecting flows and the activities that link them. As supplementary, they assist software developers to understand how better to implement several privacy properties in a more precise manner. Privacy Process Patterns (PPP) are considered a more robust way to bridge the gap between user confidentiality and cloud service providers. Privacy Pattern Properties are defined as follows [91]  
1. _Anonymity_ can be defined as a quality that does not permit the user to be identified in any form, either directly or indirectly. A problem that can arise when a user is anonymous is the issue of _Accountability_ and a large anonymity set. The benefits include location tracking freedom, users freedom of expression and low user involvement. This property can be implemented using Tor [92], Onion routing [93] and DC-nets [94]
2. _Pseudonymity_ can be defined as the utilisation of an alias instead of personally identifiable information. A problem that can arise is the issue of _Integrity_[95]. The benefits include supporting user access to services without disclosing real identities. Users still maintain integrity protocol. This property can be implemented using administrative tools such as biometrics, identity management and smart cards. 3. _Unlinkability_ can be defined as using a service or resource with the inability of third-party linkage between the user and the service. Issue: _Integrity and Accountability_. Benefits: privacy-preserving by not allowing malicious monitoring of user experience. Implementation: Onion routing, Tor and DC-nets. 4. _Undetectability_ inability of third-party tracking amongst a set of possible users. Issues: undetectability strength is highly dependent on the size of the undetectability set. Benefits: preserve users' privacy without allowing detectability of service by malicious intruders. Secondly, attackers cannot adequately detect the existence of an exact Item of Interest (IOI), e.g., the use of steganography and watermarking. Implementation: smartcards and permission management, encryption methods such as mail and transaction encryption. 5. _Unobservability_ inability to perceive the existence of a user amongst a set of potential users. Issue: dependent on the integrity level and anonymity set. Benefits: anonymity and undetectability enforcement per resources. Secondly, ensuring user experience without the connection and observability of a third-party. Implementation: smartcards and permission management. Anonymizer services such as Tor, Hordes and GAP. The literature has identified the need to introduce a Privacy by Design (PbD) to support the need for sensitive and confidential information stored, shared and distributed at the digital level [81; 82; 96]. From the literature, works are still in progress to define privacy design patterns in cloud computing. Developing a privacy pattern language will further assist developers in building the gap between the design and implementation phase. However, despite the works presented in the literature, there is still a gap between privacy design and implementation. Authors in [96] implemented and provided Privacy Process Patterns by Design that can be used to bridge gaps highlighted in the literature. The authors demonstrated the practicality of the application through JavaScript Object Notation (JSON) in conjunction with the Privacy Safeguard (PriS) methodology and applied them to a real case study. Further implementation of privacy access patterns was implemented by [81; 82; 83]. The challenges of Privacy by Design were highlighted by [PERSON] et al. as a factor of design and implementation of policies to be established by software engineers, as they lack a standard definition of privacy requirements and policies.