International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 6- June 2013
Hierarchical Attribute-Based Secure Outsourcing for
Malleable Access in Cloud Computing
S. Usha#1, Dr. A. Tamilarasi#2, K. Mahalakshmi*3
#1
Assistant Professor, Dept. of CSE, University College of Engg., Panruti Campus, Tamilnadu, India
#2
Professor & HOD, Kongu Engineering College, Perundurai,Tamilnadu, India
*
PG Scholar, Dept. of CSE, University College of Engg., (BIT Campus), Trichy, Tamilnadu, India
Abstract— This paper is an attempt to provide an enhanced data
storage security model in Cloud Computing and creating a trust
environment in cloud computing. There are a lot of compelling
reasons for businesses to deploy cloud-based storage. For a new
business, start-up costs are significantly reduced because there is
no need to invest capital up front for an internal IT
infrastructure to support the business. By far, the number one
question clients considering a move to cloud storage ask is
whether or not their data will be secure. Storing data offsite
doesn’t change data security requirements; they are the same as
those facing data stored onsite. Security should be based on
business requirements for specific applications and data sets, no
matter where the data is stored. We believe that data storage
security in Cloud Computing, an area full of challenges and of
paramount importance, is still in its infancy now, and many
research problems are yet to be identified. In this paper, we
investigated the problem of data security in cloud data storage,
to ensure the correctness of clients’ data in cloud data storage.
We proposed a Hierarchical Attribute-Based Secure Outsourcing
for mallable Access in Cloud computing which also ensures data
storage security and survivability thereby providing trust
environment to the clients. To combat against unauthorized
information leakage, sensitive data have to be encrypted before
outsourcing so as to provide end-to-end data confidentiality
assurance in the cloud and beyond. We have reduced the
computation time due to key size by implementing ECDSA
algorithm for Cryptographical operations. Also we use push mail
algorithm for key exchange between owner and consumer. It
enhances the security in the proposed model effectively.
Keywords— Cloud Computing, Access Control, Secure data
storage
I. INTRODUCTION
Cloud computing is a computing paradigm in which the
application software and databases are moved to the
centralized large data centres. Cloud computing differs from
existing hosting services. Services are based on consumption
and the technology infrastructure is optimized for hosting
several customers. Cloud Computing has been envisioned as
the next-generation architecture of IT Enterprise. It is
receiving more and more attentions, from both industrial and
academic community. Cloud computing separates usage of IT
resources from their management and maintenance, so that
clients can focus on their core business and leave the
expensive maintenance of IT services to cloud service
provider. However clients of outsourced storage are at the
mercy of their storage providers for the continued availability
ISSN: 2231-5381
of their data. Even Amazon's S3, the best-known storage
service, has experienced significant downtime. Here we are
considering scenarios where clients may have concerns of the
data security and survivability of their data stored in the cloud
storage. The management of the data and services may not be
fully trustworthy. Trust Access of clients on identity and
behaviors is significant for Network Services. In Trust
Environment, security and survivability must be provided on
network services. The client’s behaviors should be monitored
and some abnormal behaviors should be handled. In order to
increase the data storage security and to provide trust
environment in cloud, we propose architecture with
Hierarchical Attribute-based secure outsourcing to monitor
data flow to ensure data storage security and survivability
thereby providing trust environment to the clients.
Cipher text-policy attribute-based encryption (CP-ABE), as
one of the most promising encryption systems in this field
allows the encryption of data by specifying an access control
policy over attributes so that only users with a set of attributes
satisfying this policy can decrypt the corresponding data.
However a CP-ABE system may not work well when
enterprise users outsource their data for sharing on cloud
servers due to the following reasons: First, one of the biggest
merits of cloud computing is that users can access data stored
in the cloud anytime and any- where using any device such as
thin clients with limited bandwidth, CPU, and memory
capabilities. Therefore the encryption system should provide
high performance. Second, in the case of a large-scale
industry a delegation mechanism in the generation of keys
inside an enterprise is needed. IBE provides a public key
encryption mechanism where a public key is an arbitrary
string. In this paper construct two efficient Identity Based
Encryption (IBE) systems that are selective identity secure
without the random oracle and these system include an
efficient CCA2 public key cryptosystem. Although some CPABE schemes support delegation between users which
enables a user to generate attribute secret keys containing a
subset of this own attribute secret keys for other users. We
hope to achieve a full delegation that is a delegation
mechanism between attribute authorities (AAs) which
independently make decisions on the structure and semantics
of their attributes. Third, in case of a large-scale industry with
a high turnover rate, a scalable revocation mechanism is a
must. In this paper, we propose first a hierarchical attributebased encryption (HABE) model by combining a HIBE
http://www.ijettjournal.org
Page 2594
International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 6- June 2013
system and a CP-ABE system Based on the HABE model we
construct a HABE scheme by making a performanceexpressivity trade-off to achieve high performance.
Traditionally trust can be established based on identities.
Obtain local identities from system in order to access system
service. Under assumption of that entities in the systems are
already known each other. On open system like Internet
strangers can make connection and establish trust together
obviously establishing trust based on ID is not a feasible
approach. Parties may come from different security domain
and often do not have any pre-existing relationship. Therefore,
the properties of the participants will be most relevant. The
approach of automated trust negotiation differs from
traditional identity-based access control systems mainly in the
following aspects:
1) Trust between two strangers is established based on
parties’ properties. It is proven through disclosure of digital
credentials.
2) Every party can define access control policies to control
outsider’s access to their sensitive resources.
3) Instead of a one-shot authorization and authentication
trust is established incrementally through a sequence of
bilateral credential disclosures.
4) Less sensitive first. More sensitive disclosed later on as
level of trust increase.
5) When it comes to SaaS and PaaS authentication
authenticate users with your identity provider and use
federation for trust with the SaaS vendor.
6) Interestingly the CSA recommends enabling the use of a
single set of credentials valid across multiple sites for
individual users and to void vendor proprietary methods
II. RELATED WORKS
Matthew Green, Susan Hohenberger and Brent Waters [13],
In this work, we show how to delegate (in a true offline sense)
the ability to transform an ABE cipher text on message m into
an El Gamal-style cipher text on the same m, without learning
anything about m. This is similar to the concept of proxy
encryption where an untrusted proxy is given a re-encryption
key that allows it to transform an encryption under Alice’s key
of m into an encryption under Bob’s key of the same m,
without allowing the proxy to learn anything about m. IBE
provides a public key encryption mechanism where a public
key is an arbitrary string.
An IBE consists of 4 algorithms are Setup, KeyGen,
Encrypt and Decrypt. In a HIBE system identities are vectors.
A vector of dimension k represents an identity at depth k.
Rakesh Bobba, Himanshu Khurana and Manoj Prabhakaran
[14],in this paper We refer to the master-key as the private key
at depth 0 and note that an IBE system is an HIBE where all
identities are at depth 1.
Initialize: adversary select an identity ID* which he wants
to challenge
Setup: system runs the Setup algorithm and give adversary
public parameter. But the master-key keeps as itself.
ISSN: 2231-5381
Phase 1: Private Key query: adversary select an identity to
system and system will send a private key corresponding to
the identity
Phase 2: Private Key query and Decryption query Guess:
finally, adversary output a guess b’. The adversary wins if
b=b’. CPA selective-ID is not allowed to issue decryption
queries.
However, a CP-ASBE scheme must also support specific
combinations of attributes from different sets. The key idea in
our construction is to include judiciously chosen additional
values in the cipher text (and in the key) that will allow a user
to combine attributes from multiple sets all belonging to the
same user. Better supporting compound attributes and
supporting multiple numerical value assignments for a given
attribute in a single key. In order to gauge the cost of this
additional functionality we compared the encryption,
decryption and key generation times using randomly
generated policies and associated keys with those of BSW CPABE scheme.
A distributed data access control scheme that is able to
enforce fine-grained access control over sensor data and is
resilient against strong attacks such as sensor compromise and
user colluding. The proposed scheme exploits a novel
cryptographic primitive called attribute-based encryption
(ABE), tailors, and adapts it for WSNs with respect to both
performance and security requirements. The feasibility of the
scheme is demonstrated by experiments on real sensor
platforms. To our best knowledge, this paper is the first to
realize distributed fine-grained data access control for WSNs.
They also propose a novel patient-centric framework and a
suite of mechanisms for data access control to PHRs stored in
semi-trusted servers. To achieve fine-grained and scalable
data access control for PHRs, they leverage attribute based
encryption (ABE) techniques to encrypt each patient’s PHR
file. Different from previous works in secure data outsourcing
they focused on the multiple data owner scenario, and divide
the users in the PHR system into multiple security domains
that greatly reduces the key management complexity for
owners and users. A high degree of patient privacy is
guaranteed simultaneously by exploiting multi-authority ABE.
Our scheme also enables dynamic modification of access
policies or file attributes, supports efficient on-demand
user/attribute revocation and break-glass access under
emergency scenarios.
John Bethencourt, Amit Sahai, and Brent Waters [15], in
this paper they present a system for realizing complex access
control on encrypted data that we call Cipher text-Policy
Attribute-Based Encryption. By using our techniques
encrypted data can be kept confidential even if the storage
server is untrusted; moreover their methods are secure against
collusion attacks. Previous Attribute-Based Encryption
systems used attributes to describe the encrypted data and
built policies into user’s keys; while in their system attributes
are used to describe a user’s credentials and a party encrypting
data determines a policy for who can decrypt. Thus our
methods are conceptually closer to traditional access control
methods such as Role-Based Access Control (RBAC). In
http://www.ijettjournal.org
Page 2595
International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 6- June 2013
addition they provide an implementation of our system and
give performance measurements.
Vipul Goyal, Omkant Pandey, Amit Sahai, and Brent
Waters [16], they propose an access control mechanism using
cipher text-policy attribute-based encryption to enforce access
control policies with efficient attribute and user revocation
capability. The fine-grained access control can be achieved by
dual encryption mechanism which takes advantage of the
attribute-based encryption and selective group key distribution
in each attribute group. They demonstrate how to apply the
proposed mechanism to securely manage the outsourced data.
The analysis results indicate that the proposed scheme is
efficient and secure in the data outsourcing systems.
Melissa Chase and Sherman S.M. Chow [17], in this paper,
the author proposes a solution which removes the trusted
central authority and protects the user’s privacy by preventing
the authorities from pooling their information on particular
users, thus making ABE more usable in practice.
Sascha Müller , Stefan Katzenbeisser , and Claudia Eckert
[18], they introduce the concept of Distributed AttributeBased Encryption (DABE) where an arbitrary number of
parties can be present to maintain attributes and their
corresponding secret keys. This is in stark contrast to the
classic CP-ABE schemes where all secret keys are distributed
by one central trusted party. They provide the first
construction of a DABE scheme the construction is very
efficient as it requires only a constant number of pairing
operations during encryption and decryption.
Rakesh Bobba, Himanshu Khurana and Manoj Prabhakaran
[14], in this paper they introduce the concept of Attribute-sets:
A practically motivated enhancement to attribute-based
encryption Attribute-Based Encryption (ABE) Cipher textPolicy ABE (CP-ABE) is a form of ABE where policies are
associated with encrypted data and attributes are associated
with keys. Specifically we propose Cipher text Policy
Attribute Set Based Encryption (CP-ASBE) - a new form of
CP-ABE - which unlike existing CP-ABE schemes that
represent user attributes as a monolithic set in keys organizes
user attributes into a recursive set based structure and allows
users to impose dynamic constraints on how those attributes
may be combined to satisfy a policy. We show that the
proposed scheme is more versatile and supports many
practical scenarios more naturally and efficiently. We provide
a prototype implementation of our scheme and evaluate its
performance overhead.
III. SYSTEM MODEL
System-In order to achieve secure, scalable and access
control on outsourced data in the cloud, we utilize and
uniquely combine the following cryptographic techniques.
1. Key Policy Attribute-Based Encryption (KP-ABE).
2. Re-Encryption (PRE)
Low Cost: This is the very great advantages for
organisations to reduce their cost by having the cloud
computing service. Fast Service (Always Up time): Cloud
ISSN: 2231-5381
computing service providers having infrastructure so server
always in up-time. The amount of decryption code that needs
to reside on a resource constrained user device will be smaller.
Reduction: Bilinear Decisional Diffie-Hellman, Collusion
resistance and can’t combine private key components.
Domain
Authroity
Trusted
Authroity
Data Owner
Domain
Authroity
Data Owner
Secured
Cloud
Domain
Authroity
Figure 1: Our Proposed System Model
IV. ALGORITHM
The Elliptic Curve Digital Signature Algorithm (ECDSA)
is a variant of the Digital Signature Algorithm (DSA) which
uses elliptic curve cryptography. As with elliptic curve
cryptography in general the bit size of the public key believed
to be needed for ECDSA is about twice the size of the security
level in bits. By comparison in the security level of 80 bits
meaning an attacker requires the equivalent of about 280
signature generations to find the private key the size of a DSA
public key is at least 1024 bits whereas the size of an ECDSA
public key would be 160 bits. On the other hand, the signature
size is the same for both DSA and ECDSA: 4t bits, where t is
the security level measured in bits that are about 320 bits for a
security level of 80 bits.
Suppose Alice wants to send a signed message to Bob.
Initially the curve parameters (CURVE, G, n) must be agreed
upon. In addition to the field and equation of the curve we
need G a base point of prime order on the curve; n is the
multiplicative order of the point G.
Alice creates a key pair, consisting of a private key integer
dA randomly selected in the interval [1, n-1] and a public key
curve point QA=dA*G. We use * to denote elliptic curve point
multiplication by a scalar.
For Alice to sign a message m follows these steps:
1. Calculate e=HASH (m), where HASH is a
cryptographic hash function, such as SHA-1.
2. Let Z be the Ln leftmost bits of e, where Ln is the
bit length of the group order n.
3. Select a random integer k from [1, n-1].
4. Calculate the curve point(x1, y1) = k*G.
5. Calculate r=x1(mod n). If r=0, go back to step 3.
6. Calculate s=k-1(Z+rdA) (mod n). If s=0, go back to
step 3.
7. The signature is the pair(r, s).
http://www.ijettjournal.org
Page 2596
International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 6- June 2013
V. SIMULATION WORKS/RESULTS
We have simulated our system in Java. We implemented
and tested with a system configuration on Intel Dual Core
processor, Windows XP and using Netbeans 7.0. We have
used the following modules in our implementation part. The
details of each module for this system are as follows:
Authority Management: There are three levels of authority in
this hierarchal management. The trusted authority is the root
authority and responsible for managing top-level domain
authorities. Each top-level domain authority corresponds to a
top-level organization, such as an enterprise. Each lower-level
domain authority corresponds to a lower-level organization
such as an affiliated company in that enterprise. Data
owners/consumers may correspond to employees in an
organization. Each domain authority is responsible for
managing the data owners and consumers in its domain.
Authentication: All the 3 authorities need to be
authenticated in order to access their service. Authentication
helps to prevent the data from the illegal access.
Data Storage: The cloud service provider manages a cloud
to provide data storage service. Data owners encrypt their data
files and store them in the cloud for sharing with data
consumers.
Data Access: To access the shared data files, data
consumers download encrypted data files of their interest from
the cloud and then decrypt them. In our scheme, a data owner
specifies an access structure for a cipher text which is referred
to as the cipher text policy. Only users with decryption keys
whose associated attributes specified in their key structures
satisfy the access structure can decrypt the cipher text.
To evaluate our outsourcing systems we implemented the
CP-ABE version is associated Outsourcing decryption
resulted in significant practical benefits. Decrypting on an
ABE cipher text containing 100 attributes we found that
without the use of a proxy the mobile device would require
about 30 seconds of computation time and drain a significant
amount of the device’s battery. When we applied our
outsourcing technique decrypting the cipher text took 2
seconds on our Intel server and approximately 60 milliseconds
on the mobile device itself. To demonstrate compatibility
with existing infrastructure we constructed a re-usable
platform for outsourcing decryption using the Amazon EC2
service. Our proxy is deployed as a public Amazon Machine
Image that can be programmatically instantiated by any
application requiring acceleration. In addition to the core
benefits of outsourcing we discovered other collateral
advantages.
In existing ABE implementations much of the decryption
code is dedicated to determining how a policy is satisfied by a
key and executing the corresponding pairing computations of
decryption. In our outsourcing solution most of this code is
pushed into the untrusted transformation algorithm leaving
only a much smaller portion on the user’s device. A domain
authority is trusted by its subordinate domain authorities or
users that it administrates, but may try to get the private keys
ISSN: 2231-5381
of users outside its domain. Users may try to access data files
either within or outside the scope of their access privileges, so
malicious users may collude with each other to get sensitive
files beyond their privileges.
Figure 2: Implementation Screens on Key generation
Figure 3: Implementation Screens on Data Authority login
Figure 4: Implementation Screens displaying access levels
http://www.ijettjournal.org
Page 2597
International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 6- June 2013
VI. CONCLUSION & FUTURE WORK
Figure 5: Implementation Screens on Key generation
In this paper, we investigated the problem of data security
in cloud data storage, which is essentially a distributed storage
system. To ensure the correctness of clients’ data in cloud data
storage, we proposed a Hierarchical Attribute-Based Secure
Outsourcing for mallable Access in Cloud computing which
also ensures data storage security and survivability to secure
and monitor Data flow. By utilizing the security key, proposed
architecture achieves the integration of storage correctness
insurance and survivability, i.e., whenever data corruption has
been detected during the storage correctness verification in
cloud storage server, we can almost guarantee the
simultaneous identification of the misbehaving server(s).
Also, we proposed a new novel technique to get realizing
scalable, fine-grained access control in the cloud computing
and to produce the work with flexible, new method called
HASBE. In this scheme, seamlessly incorporates a
hierarchical structure of the system users by applying a
delegation algorithm to ABSE. This scheme not only supports
the flexible attributions but also achieves the efficient user
revocation. We formally proved the security of HASBE based
on the security of CP-ABE by Bethencourt. Finally, we
implemented the proposed scheme, and conducted
comprehensive performance analysis and evaluation, which
showed its efficiency and advantages over existing schemes.
Figure 6: Implementation Screens on Key Decryptor
[1]
VII.
[2]
First we observe that while key validity is limited because
of the window of the actual attribute assignments change far
less frequently. Second we observe that it is possible to add
attributes retroactively to a user key both in CP-ABE and CPASBE, if key server is able to maintain some state information
about the user key. Then by allowing multiple value
assignments to the expiration time attribute we can simply add
a new expiration value to the existing key. Thus while we
require the key server to maintain some state we avoid the
need to generate and distribute new keys on a frequent basis.
This reduces the burden on the key server by a factor
proportional to the average number of attributes in user keys.
In our system, neither data owners nor data consumers will be
always online. They come online only when necessary while
the cloud service provider, the trusted authority, and domain
authorities are always online. The cloud is assumed to have
abundant storage capacity and computation power. In addition,
we assume that data consumers can access data files for
reading only.
[3]
[4]
[5]
[6]
[7]
[8]
[9]
[10]
ISSN: 2231-5381
REFERENCES
H. Liu, P. Wan, X. Jia, X. Liu, and F. Yao, “Efficient flooding scheme
based on 1-hop information in mobile ad hoc networks,” In Proc. IEEE
INFOCOM, 2006.
J. Wu, W. Lou, and F. Dai, “Extended multipoint relays to determine
connected dominating sets in manets,” IEEE Trans. on Computers,
vol. 55, no. 3, pp. 334–347, 2006.
M. Khabbazian and V. K. Bhargava, “Efficient broadcasting in mobile
ad hoc networks,” IEEE Transactions on Mobile Computing: accepted
for publication, 2008.
J. Wu and F. Dai, “Broadcasting in ad hoc networks based on
selfpruning,” In Proc. IEEE INFOCOM, pp. 2240–2250, 2003.
W. Peng and X. Lu, “On the reduction of broadcast redundancy in
mobile ad hoc networks,” In Proc. ACM Interational Symposium on
Mobile Ad Hoc Networking and Computing (MobiHoc), pp. 129–130,
2000.
I. Stojmenovic, M. Seddigh, and J. Zunic, “Dominating sets and
neighbor elimination-based broadcasting algorithms in wireless
networks,”IEEE Trans. on Parallel and Distributed Systems, vol. 13, pp.
14–25, 2002.
M. Khabbazian and V. K. Bhargava, “Localized broadcasting with
guaranteed delivery and bounded transmission redundancy,” IEEE
Transactions on Computers, vol. 57, no. 8, pp. 1072–1086, 2008.
J. Wu and F. Dai, “A generic distributed broadcast scheme in ad hoc
wireless networks,” IEEE Transactions on Computers, vol. 53, no. 10,
pp. 1343–1354, 2004.
P. Nand and S.C. Sharma, “ Probability based improved broadcasting
for AODV Routing protocol”, “ IEEE International Conference on
Computational Intelligence and Communication Networks, 2011.
D. Dembla and Y. Chaba, “ Performance Modeling of Efficient and
Dynamic Broadcasting Algorithm in MANETs Routing Protocols”,
http://www.ijettjournal.org
Page 2598
International Journal of Engineering Trends and Technology (IJETT) – Volume 4 Issue 6- June 2013
[11]
[12]
[13]
[14]
[15]
IEEE International Conference on Computer Research and
Development, 2010.
S. Preethi, B. Ramachandran, “ Energy Efficient routing protocols for
mobile AdHoc networks”, IEEE International Conference on Emerging
Trends in Networks and Computer Communications, 2011.
P. Nand and S.C. Sharma, “Comparative Analysis of Broadcasting
Techniques for Routing Protocols”, IEEE International Conference on
Devices and Communications”, 2011.
Matthew Green, Susan Hohenberger and Brent Waters, “Outsourcing
the Decryption of ABE Ciphertexts”.
Rakesh Bobba, Himanshu Khurana and Manoj Prabhakaran,
“Attribute-Sets: A Practically Motivated Enhancement to AttributeBased Encryption”, July 27, 2009.
John Bethencourt, Amit Sahai, and Brent Waters, “Ciphertext-Policy
Attribute-Based Encryption”.
ISSN: 2231-5381
[16]
[17]
[18]
Vipul Goyal, Omkant Pandey, Amit Sahai, and Brent Waters,
“Attribute-Based Encryption for Fine-Grained Access Control of
Encrypted Data”.
Melissa Chase and Sherman S.M. Chow, “Improving Privacy and
Security in Multi-Authority Attribute-Based Encryption”.
Sascha Müller , Stefan Katzenbeisser ,
and Claudia Eckert,
“Distributed Attribute-Based Encryption”, in international conference
on information security and cryptography in year 2008.
http://www.ijettjournal.org
Page 2599