Query homogeneity attacks

2. Query homogeneity attacks • Problem: • The attacker want to infer information from the sensitive attribute(s) involved in a user’s request => query association

3. Two methods to prevent query association: • Many-to-one queries: a k-anonymous cloaking region <-> single service attribute => k potential users who may be the owner of the service attribute • Many-to-many queries: a cloaking region <-> a set of service attribute values (ones belonging to the users inside the region)

4. Example

5. l-diversity • Query l-diversity: ensures that a user cannot be linked to less than ℓ distinct service attribute values. equivalence class (EC)

6. t-closeness all disease is stomach problem

7. l-diversity & t-closeness • Satisfying location k-anonymity • Satisfying query ℓ-diversity • Satisfying query t-closeness query 3-diverse and location 3-anonymous

8. m-Invariance • Query m-Invariance: the number of possible query association attacks will increase if a user can be associated with more number of service attribute values.