Download - Data Integrity proofs in cloud storage
DATA INTEGRITY PROOFS IN
CLOUD STORAGE
by
Mohd Abdul Sameer
Index1.Cloud Computing- Services- Saas- Iaas- Paas
2.Need For Data Integrity- Future applications- Issues in cloud computing
3.Data Integrity- Proof of Retrievability- conclusion- Future Enhancement
What is Cloud Computing. . . . . . . .?
Applications and services that run on a distributed network using virtualized resources and accessed by common internet protocols and network standards (or)
Cloud Computing is a paradigm in which information is permanently stored in servers on the internet and can be accessed from anywhere
Cloud Computing
Services Provided By Cloud Computing
Cloud Services
IAAS (Infrastructure As a Service)Traditional business organizations
Data centerOffice spaceServers and storagesTeam of technical personnel'sCoolantsNetworkPower
New Model of business organizations
Provides all the infrastructure needed to run applications over the internet
Benefits
Increased storage Reduced cost Flexibility Increased mobility Highly automated
SAAS (Software As a Service) -> 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
Benefits No local storageSmarter to rentOn demand
PAAS (Platform As a Service)
• ….enables you to create web applications quickly, without the
• cost and complexity of buying and managing the underlying software or hardware…
• Benefits
No Frequent updatesInexpensive
Future Applications of Cloud
Vulnerabilities of Cloud Computing
Data Integrity and
Data Privacy
Availability and
Reliability
Bandwidth and Latency guarantees
Portabilityand
Compliance
Data Integrity Proofs In Cloud StorageCloud 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
Our schemeWe 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…
(SLA) Service level Agreement
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.
ARCHITECTURE
Key generator: A random key is generatedEncryption: A metadata of the file is generated and is encrypted using any suitable algorithmArchive: It is the data center where the data is outsourcedChallenge: Verification of data integrity by the user…Response: Proof of data integrity by data center
Existing System
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
CHALLENGE
Response
Drawbacks of this approach• 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….
Ari Juels and Burton S.kaliski jrProposed 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
sss
ss 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
Verification Phase
Drawbacks:Computationally burdensome for entire file to be encrypted for small devicesThis scheme is best suited for encrypted files
DataCenter
Owner challenges cloud by specifying the positions of collection of sentinels
If the file is modified then position of sentinels also changes
CloudStorage
Client
Proposed SystemIn this we provide a scheme of data integrity , which the customer can utilize to check the correctness of his data by including SLA
Note: our proof of data integrity just check the integrity of data i.e. if data has been illegally deleted or modified.Applicable only for static data We provide a scheme which does not involve the encryption of the entire file, we encrypt only few bitsVerifier stores only a single key
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
Fig : Generation of Metadata
File (F) Metadata
DataCenter
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
Fig : Verification Phase
Conclusion Facilitate the client for getting a
proof of integrity Computational and storage overhead
of client as well cloud is exceptionally reduced
Advantageous to thin client like PDA’s, Mobiles, Laptops Network bandwidth is minimized as the size of proof is comparatively less
Modules
1. Cloud storage:Which is supposed to be for a “FEE”. Store the data and provide it back to the owner whenever required.
2. Simply archives: obtains and verify the proof for data that is stored by user at remote data storage in the cloud
3. Sentinels:Guards the positions of bits
4. Verification phase:challenge the cloud by providing the bit positions for a correct response
Future improvement
Our scheme is only for static data
Developing for dynamic data will be a future challenge