Figure 4 An example of encrypted metadata set.
Here max denotes the maximum number of score duplicates within the metadata set.
δ denotes the totoal number of scores to be mapped within metadata set.
With the established file metadata set, it is easy to determine the proper rage size |R|.
The encrypted files and metadata set are outsourced to the server by the owner.
Finally the owner uploads both the encrypted file collection C and metadata set M to the cloud server.
M − the encrypted metadata set, denoted as a set of n file metadata M = {M(F i )}, i = 1, 2, ⋯ n.
With the metadata set, the cloud server builds the inverted index and constructs semantic relationship library (SRL) for the keywords set.
If file F i contains keyword w j, a tuple w j, s ji is insert into metadata M(F i ), where s ji represents the relevance score of keyword w j response to file F i. All of the file metadata constitute metadata set, which is shown in Figure 3. Figure 3 An example of metadata set.
In our construction we should scan the whole metadata set to extract the keywords and build the inverted index with corresponding scores.
