Data Integrity proofs in cloud storage


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Data Integrity proofs in cloud storage

  1. 1. Applications and services that run on a distributed network using virtualized resources and accessed by common internet protocols and network standards Cloud Computing is a paradigm in which information is permanently stored in servers on the internet and can be accessed from anywhere
  2. 2. Data center Office space Servers and storages Team of technical personnel's Coolants Network Power
  3. 3. Provides all the infrastructure needed to run applications over the internet  Increased storage  Reduced cost  Flexibility  Increased mobility  Highly automated
  4. 4. -> Sometimes referred to as "on-demand software" is a software delivery model in which software and its associated data are hosted centrally and are typically accessed by users
  5. 5. • ….enables you to create web applications quickly, without the • cost and complexity of buying and managing the underlying software or hardware… No Frequent updates Inexpensive
  6. 6. Data Integrity and Data Privacy Availability and Reliability Bandwidth and Latency guarantees Portability and Compliance
  7. 7. Cloud storage moves the user’s data to large data centers, which are remotely located, on which the user does not have any control However there are lot of security issues which need to be considered  Data integrity  Authentication  Small devices like PDA’s, mobiles, and laptops are associated with limited battery power and computation speed
  8. 8. We provide a scheme which gives a proof of data integrity in the cloud through which the user can verify the correctness of his data, this proof can be termed as Proof of Retrievability (POR)  This enables individual to entertain  Economic advantages  Zero Maintenance Note: -> Our scheme just checks the integrity (if the data is illegally modified) only of static data…
  9. 9.  This proof can be agreed upon by both the cloud and the customer and can be incorporated in SLA. SLA is part of service contract where the level of services being offered is formally defined.
  10. 10. Key generator: A random key is generated Encryption: A metadata of the file is generated and is encrypted using any suitable algorithm Archive: It is the data center where the data is outsourced Challenge: Verification of data integrity by the user… Response: Proof of data integrity by data center
  11. 11. A simplest Proof of Retrievability can be made using hash key function File (F) Data Center (archive) Cryptographic Hash Function Hk(F) User DB Hash Secret key (k) Encrypted file(~f) StoredRetrieves C H A L L E N G E Response
  12. 12. • Computing hash value for moderately large file might be overhead for some device like Mobiles, PDA’s and Laptops • For each verification request from client the archive has to process the entire file • High resource cost and lot of ambiguity as a result of maintaining secret key and number of hash keys….
  13. 13. Proposed a theory to proof the retrievability for large files using sentinels…. According to them 1 2 3 4 5 6 7 Data File( f ) s s s s s s s s s s s s s s s s s s s s s Data file with seven blocks Inserting sentinels at different positions and noting their position, present at different blocks File(~f) Encryption (~F ) Data Archive To hide the position of sentinels
  14. 14. Computationally burdensome for entire file to be encrypted for small devices This scheme is best suited for encrypted files Data Center Cloud Storage Client
  15. 15. In this we provide a scheme of data integrity , which the customer can utilize to check the correctness of his data by including SLA
  16. 16. M bits M bits M bits M bits M bits M bits File (F) with n blocks, and each block of size M bits K bits K<<<M, K bit positions are noted Where K is user defined E M1 K bits E M2 K bits E M3 K bits E M4 K bits E M5 K bits E M6 Metadata Encrypting k bits using any appropriate algorithm Generation of individual metadata
  17. 17. File (F) Metadata Data Center File is appended with metadata New file (~F) is stored at data center Client challenges by specifying (ith) block of file and the jth bit of i Response and challenge should be same to accept the file
  18. 18. Our scheme is only for static data Developing for dynamic data will be a future challenge