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Improving the Security of Searchable Encryption Schemes

Ameri Ekhtiarabadi, Mohammad Hassan | 2015

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 47469 (05)
  4. University: Sharif University of Technology
  5. Department: Electrical Engineering
  6. Advisor(s): Mohajeri, Javad; Salmasizadeh, Mahmoud
  7. Abstract:
  8. In todays world, the importance of cloud computing is not deniable. Because, it provides an environment for accessing to a lot of useful applications in a convenient way with low cost. Cloud storage is one of such services which is provided by cloud computing. As the cloud providers are not fully trusted, it is necessary to encrypt the data before outsourcing, to preserve the privacy of stored information. To find a set of document which is related to some keywords, it is possible to designate cloud provider to search on behalf of entities. So, the encrypted data should be searchable and one solution which is suggested is searchable encryption. Related to this cryptographic primitive, there has been presented some schemes with different security aspects. But some of this schemes’ problems has remained open. Proposing a generic construction for verifiable attribute based keyword search and applying time limitation on the period of validity of search tokens are two examples of these open problems. In this thesis, a generic construction for verifiable attribute based keyword search (VABKS) based on Bloom filter, hierarchical identity-based multi designated verifier signature (HIB-MDVS) and hierarchical identity-based broadcast encryption (HIBBE) is proposed and its security is proved in the standard model. So, HIB-MDVS is introduced and its unforgeability and the anonymity of HIBBE is defined in a formal way. It is proved that the security of proposed scheme is based on unforgeability of HIB-MDVS and anonymity of HIBBE. Also the concept of attribute based temporary keyword search (PETKS) has been introduced and a concrete structure has been proposed based on bilinear Diffie-Hellman problem. In the proposed scheme it is possible to apply a time limitation on the validity of generated search token and the data owners are able to designate a set of data users with specific attributes to generate a time limited valid search token
  9. Keywords:
  10. Cloud Computing ; Provable Security ; Attribute Based Encryption ; Cloud Storage ; Searchable Encryption ; Hierarchichal Identity-based Cryptography

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