A Method for Searching on Encrypted Data

Mansoori, Fatemeh | 2009

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 39477 (19)
  4. University: Sharif University of Technology
  5. Department: Computer Engineering
  6. Advisor(s): Jalili, Rasool
  7. Abstract:
  8. Using database encryption to protect data in some situations where access control is not soleley enough is inevitable. Database encryption provides an additional layer of protecton to conventional access control techniques. It prevents unauthorized users, including intruders breaking into a network, from viewing the sensitive data. As a result data remains protected even in the event that database is successfully attacked or stolen. However, encryption and decryption of data result in database performance degradation. In the situation where all the information is stored in encrypted form, one cannot make the selection on the database content any more. Data should be decrypted first, so an unwilling tradeoff between the security and the performance is normally forced. The appropriate approaches to increase the performance are methods to deal directly with the encrypted data without firstly decrypting them. In this Thesis, we study various approaches to query encrypted databases, and introduce two efficient and secure schemes called PSSIS and ROPES. PSSIS provides searching of arbitrary patterns in the fields' content. ROPES enhanced the security of OPES (a method which provides executing range queries in encrypted databases). The proposed methods suppose that the database management server is untrusted and must be prevented from viewing the sensitive data. In the proposed schemes, search on encrypted data is done as efficient as on unencrypted data, where the record containing a given value can be retrieved in time logarithmic to the database size. Despite the other methods, the result returned by a query on the encrypted table has exactly the same result as it is done on the corresponding non-encrypted table. Our security analysis of the schemes indicates that anyone having access to the encrypted database and also some corresponding plaintext data can learn nothing about database content unless having access to the related encryption keys and also the schemes don't suffer from inference analysis
  9. Keywords:
  10. Data Security ; Encrypted Database ; Encrypted Query ; Database Security

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