security in cloud computing, one key encryption & bio metric authentication

2 levels in a cloud computing environment. First a one time key encryption mechanism for data protection and second level a bio metric ( e.g finger print) authentication for identity management is carried out.

framework theoretically that how this process will work if a file is operated by a service provider in cloud based environment. What will be the proposed features for the above related problem in the prototype application. Like how a file comes and then processed in cloud based environment with reference to 2 level security environment as above describe
What are previous applications working in similar domain and how?