Key aggregate cryptosystem for scalable data sharing in cloud

T.SRAVANI
(11541A0538)
G.KOTESWARA RAO M.ABHILASH
(11541A0509) (11541A0521)
P.SHEETALCHAITANYA M.VASUDEVA REDDY
(11541A0529) (11541A0515)
Under The Guidence Of
G.SURESH KUMAR, M.Tech

CONTENTS
 Introduction
 Abstract
 Existing System
 Proposed System
 System Architecture
 Modules
 System Requirements

INTRODUCTION
 The word Cloud Computing mean?
 What does Cloud Computing mean?
 In the Cloud Computing the apps and files are hosted
consisting of thousands of computers and servers &and
linked together ,they are accessed via internet.
 By using Cloud Computing we can access all the apps and
documents from anywhere in the world.

ABSTRACT
 Data sharing is an important functionality in cloud storage.
 Here we show how to securely, efficiently, and flexibly
share data with others in cloud storage.
 We describe new public-key cryptosystems that produce
constant-size ciphertexts.
 One can aggregate any set of secret keys and make them as
compact as a single key, but encompassing the power of all
the keys being aggregated.

 The secret key holder can release a constant-size
aggregate key for flexible choices of ciphertext set.
 This compact aggregate key can be conveniently sent
to others or be stored in a smart card with very
limited secure storage.
 We also describe other application of our schemes.
 In particular, our schemes give the first public-key
patient-controlled encryption for flexible hierarchy,
which was yet to be known.

EXISTING SYSTEM
 Considering data privacy, a traditional way to ensure
it is to access control after authentication, which
means any unexpected privilege escalation will
expose all data.
 In a shared-tenancy cloud computing environment,
things become even worse.
 Regarding availability of files, there are a series of
cryptographic schemes which go as far as allowing a
third-party auditor to check the availability of files of
the data owner without leaking

DISADVANTAGES OF EXISTING SYSTEM
 The costs and complexities involved generally
increase with the number of the decryption keys
to be shared.
 The encryption key and decryption key are
different in publickey encryption.

PROPOSED SYSTEM
 In this paper, we study how to make a decryption key
more powerful in the sense that it allows decryption
of multiple ciphertexts, without increasing its size.
 Specifically, our problem statement is “To design an
efficient public-key encryption scheme which
supports flexible delegation in the sense that
any subset of the ciphertexts is decry ptable by a
constant-size decryption key ”.
 We solve this problem by introducing a special type
of public-key encryption which we call key-aggregate
cryptosystem (KAC).

 In KAC, users encrypt a message not only under a
public-key, but also under an identifier of
ciphertext called class.
 The key owner holds a master-secret called
master-secret key, which can be used to extract
secret keys for different classes.
 the extracted key have can be an aggregate key
which is as compact as a secret key for a single
class, but aggregates the power of many such
keys

ADVANTAGES OF PROPOSED SYSTEM
 The extracted key have can be an aggregate key
which is as compact as a secret key for a single
class.
 The delegation of decryption can be efficiently
implemented with the aggregate key.

MODULES
 Setup Phase
 Encrypt Phase
 Key Gen Phase
 Decrypt Phase

Setup Phase
 The setup algorithm takes no input other than the
implicit security parameter.
 It outputs the public parameters PK and a master key
MK.

Encrypt Phase
 Encrypt(PK,M, A). The encryption algorithm takes as
input the public parameters PK, a message M, and an
access structure A over the universe of attributes.
 The algorithm will encrypt M and produce a ciphertext
CT such that only a user that possesses a set of
attributes that satisﬁes the structure will be able to
decrypt the message.

Key Gen Phase
 Key Generation(MK,S). The key generation algorithm takes
as input the master key MK and a set of attributes S that
describe the key. It outputs a private key SK .
 This can be observed in the architecture as shown in the
next slide

Key aggregate cryptosystem for scalable data sharing in cloud

Decrypt Phase
 Decrypt(PK, CT, SK). The decryption algorithm takes
as input the public parameters PK, a ciphertext CT,
which contains an access policy A, and a privatekey SK,
which is a private key for a set S of attributes.
 If the set S of attributes satisﬁes the access structure A
then the algorithm will decrypt the ciphertext and
return a message M.

SYSTEM REQUIREMENTS
HARDWARE REQUIREMENTS:-
 System : Intel i3 processor
 Hard Disk : 40 GB
 Monitor : 15 VGA Colour
 Ram : 1 Gb
SOFTWARE REQUIREMENTS:-
 Operating system : Windows XP/7.
 Coding Language : JAVA/J2EE
 IDE : Netbeans 7.4
 Database : MYSQL

Key aggregate cryptosystem for scalable data sharing in cloud

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