International Journal of Engineering Trends and Technology (IJETT) – Volume 31 Number 2- January 2016
A Secure and Novel Key Aggregation Mechanism for
Multiple Data owners
BalaMuralikrishna. Bokka1, Saran Kumar Kuchibhatala2, Ramesh Challagundla3
1,2,3
Final M.Tech Student1, Assistant Professor2, Professor3
Dept of CSE, Pydah college of engineering and Technology, AP, India
size. Blocks of 64 bits have been
commonly used.
Abstract:
Key aggregation mechanism over cloud between
multiple owners is always an interesting research
issue in the field of secure cloud computing .Simple
symmetric and asymmetric approach may not give
the optimal results, so it is a polynomial approach
where aggregated key can be generated from
multiple users and distributed asynchronously.
Here the key can be computed from part of the
shared keys from all the users and data can be
encoded with a novel cryptographic approach
which uses coefficient sets and reminder sets. Our
experimental results show more accurate results
than traditional approaches.
I. INTRODUCTION
Cloud computing is also known as Ondemand computing. It is a kind of internet based
computing, where shared resources, data and
information are provided to the computers and
other devices. Cloud computing is a model for
enabling ubiquitous, convenient, on-demand access
to shared pool of configurable computing resources
that can be rapidly provisioned and released with
minimal management effort. Cloud computing also
focuses on maximizing the effectiveness of shared
resources. Cloud resources are not only shared by
multiple users but also dynamically reallocated per
demand. With cloud computing, multiple users can
access a single server to retrieve and update their
data without purchasing licenses for different
applications.
Symmetric key is a key which is used for
encryption of plain text and decryption of cipher
text. The keys represent shared secret between two
or more parties that can be used to maintain private
information. Symmetric key encryption can use
either stream ciphers or block ciphers.


Stream ciphers encrypt the digits of a
message once at a time.
Block cipher takes a number of bits and
encrypt them as a single unit, padding the
plain text so that it is a multiple of block
SSN: 2231-5381
Asymmetric keys are also known as
public/private keys. They are used for asymmetric
encryption. Asymmetric encryption is mainly used
to encrypt and decrypt session keys and digital
signatures. Asymmetric encryption uses public key
encryption algorithm.
Public key algorithms use two different keys.
They are public key and private key. Public key
can be distributed to anyone who requests for it
and private key must be kept secret and secure
Encryption is the best way to achieve data
security. Encryption is nothing but conversion of
plain text into cipher text. Unencrypted data is
called plain text and encrypted data is called cipher
text. Blowfish, AES, RC4, RC5 and RC6 are the
examples of encryption algorithms.
Decryption is the reverse process of encryption. It
is the process of converting the cipher text into
plain text. To make the data securable, plain text
(data) can be encrypted with secret key, the
encrypted data is called cipher text. To get the
plain text, cipher text can be converted into plain
text with particular algorithm.
II. RELATED WORK:
Even though various traditional approaches
proposed by the authors, every approach has their
own drawbacks and their advantages. In existing
model, the data owner establishes the public
system parameter via Setup and generates a
public/master-secret key pair via KeyGen.
Messages can be encrypted via Encrypt by anyone
who also decides what cipher text class is
associated with the plaintext message to be
encrypted. The data owner can use the mastersecret to generate an aggregate decryption key for
a set of cipher text classes via Extract. The
generated keys can be passed to delegates securely
(via secure e-mails or secure devices) finally, any
user with an aggregate key can decrypt any cipher
http://www.ijettjournal.org
Page 83
International Journal of Engineering Trends and Technology (IJETT) – Volume 31 Number 2- January 2016
text provided that the cipher text‟s class is
contained in the aggregate key via Decrypt, but
problem with this traditional mechanism is more
complex and may not provide optimal security.
Cloud is a resource area where we can store and
retrieve whenever access the data, various roles
involved while cloud computing. Data owner is the
person who stores and retrieves the data from
server, Cloud service provider allows data owner
to buy storage space and can manipulate the space
whenever required. End users can consume the
services provided by data owner. One more
specific role involved in cloud computing i.e.,
auditor, he audits or monitors the data uploaded
into the server and gives updates to the respective
data owner.
Data authentication and confidentiality are the
important factors while transmission of data
components over network, because data owner
does not know the physical location of the data
component which is stored, so data owners needs
to handle the authentication and data privacy or
confidentiality. Authentication explains about the
authorization of the user, only valid or
authenticated person can access the data resources
which are uploaded. Cryptographic approaches
maintain data confidentiality and privacy while
transmission of data components. Data component
can be encoded with key which is generated from
group key protocol securely along with
authentication.
Our group key generation mechanism generates an
efficient and dynamic session key between key
generation center and users without direct
transmission of key. It is a three level approach,
first level identifies the authentication of the
connected users, after the authentication of users
key can be generated by the key generation center
and embeds in to polynomial equation along with
some constants and generates few points which
satisfies the polynomial equation and forwards half
of the points to individual users, points may not be
the same to the all users. Users constructs three
equations from the received points and integrates
the all three equations and extracts the key from
the equation and uses this key for encoding and
decoding with efficient and simple cryptographic
approach.
Key Generation :
Key Generation process
The
goal
is
to
divide
a safe combination)
secret
into
data
(e.g.,
pieces
of
in such a way that:
1. Knowledge of any
makes
pieces
easily computable.
2. Knowledge
fewer
or more
of
any
pieces leaves
or
completely
undetermined (in the sense that all its
possible values are equally likely).
III. PROPOSED SYSTEM
In this paper we propose an efficient key
aggregate mechanism for secure key generation
between multiple cloud users. It can be constructed
from shared key pairs from the individual users
,key can be easily distributed to the new users even
though they are not directly communicates with
other group people and encoding mechanism
maintain data confidentiality with coefficient
vectors and reminder vector without forwarding
the data component directly. This proposed
approach is simple and stronger in performance
and security factors because key need not to be
forwarded directly to any one and data cannot be
transmitted directly or simply in terms of cipher
blocks.
SSN: 2231-5381
This scheme is called
If
threshold scheme.
then all participants are required to
reconstruct the secret.
Example
• Let us consider S=1234 (Secret key)
•
Consider n=6 and k=3 and obtain any
random integers a1=166 and a2=94
f(x)=1234+166x+94x2
• Secret
share
points
D0=
(1,1494),D1=(2,1942)D3=(3,2598)D4=(4,3
402)D5=(5,4414)D6=(6,5614)
We give each participant a different single
point (both x and f(x)). Because we use Dx-1
instead of Dx the points start from (1, f(1)) and not
(0, f(0)). This is necessary because if one would
have (0, f(0)) he would also know the secret
(S=f(0))
http://www.ijettjournal.org
Page 84
International Journal of Engineering Trends and Technology (IJETT) – Volume 31 Number 2- January 2016
R[I]=I(mi)%Δ
Re-construction
In order to reconstruct the secret any 3 points will
be enough
Let us consider
(x0,y0)=(2,1924),(x1,y1)=(4,3402),(x2,y2)=(5,4414)
Using lagrangeous polynomials
L0=x-x1/x0-x1*x-x2/x0-x2=x-4/2-4*x-5/25=(1/6)x2-(3/2)x+10/3
L1=x-x0/x1-x0*x-x2/x1-x2=x-2/4-2*x-5/4-5=-(1/2)x2(7/2)x-5
L2=x-x0/x2-x0*x-x1/x2-x1=x-2/5-2*x-4/5-4=(1/3)x22x+8/3
f(x)=j * lj(x) =1942((1/6)x2-(3/2)x+10/3)+3402((1/2)x2-(7/2)x-)+4414((1/3)x2-2x+8/3 )
f(x)=1234+166x+94x2
Recall that the secret is the free coefficient, which
means that S=1234.
Find Q
Q[I]=I(mi)/Δ
Representation of R
For I=1 to n
Represent R[I] in base Δ
Representation of Q
Uses the Compression mechanism.
Converts Base B quotients to Base 10
Encoding and Decoding:
MOD-ENCODER Decoding Algorithm:
This algorithm uses a finite alphabet set,
constant value Δ for encryption and a decryption of
the message and is used as a secret key. This Δ is
generated using Diffie-Hellman key generation
algorithm to provide more security to algorithm.
The sender generates Remainders and Quotients
using Δ value and the compression performs only
Input : Bi-tuple <R,Q>, Δ value
Convert Q from Base 10 to Base B
Let QB=(q1,q2,….qn) be the representation in
Base B
Interpret R as a vector of Base Δ number
on the Quotient vector further these two values
forwarded
to
the
receiver
to
ensure
the
confidentiality of the message. The receiver
For 1 ≤ i ≤n
I=qi × Δ + ri
decompresses and decodes the message using
compressed quotient and remainder vector.
Where qi the ith digit of QB,ri the ith element of R.
Mi=I-1(i)
MOD-ENCODER Encoding Algorithm:
M=(m1,m2,….mn)
Input : M ∈ ∑, Δ value
CONCLUSION
N=|M|, i.e length of M
Z=n * bit size, i.e bit size is the number of bits
require to represent each character
For i=1 to n
Read mi the ithcharacter from M
Find R
SSN: 2231-5381
We have been concluding our current research
work with efficient key aggregate system with key
generation and encoding and decoding mechanism.
Secure key can be generated with lagranges
polynomial equation and reconstruction. Data
confidentiality can be maintained with quotient and
reminder vector model along with the key
generated with polynomial equation. Our proposed
solution gives optimal solution than traditional
approach .
http://www.ijettjournal.org
Page 85
International Journal of Engineering Trends and Technology (IJETT) – Volume 31 Number 2- January 2016
REFERENCES
[1] M. Armbrust, A. Fox, R. Griffith, A.D. Joseph, R.H. Katz,
A. Konwinski, G. Lee, D.A. Patterson, A. Rabkin, I. Stoica, and
M. Zaharia, “A View of Cloud Computing,” Comm. ACM, vol.
53, no. 4, pp. 50-58, Apr. 2010.
[2] S. Kamara and K. Lauter, “Cryptographic Cloud Storage,”
Proc. Int‟l Conf. Financial Cryptography and Data Security
(FC), pp. 136- 149, Jan. 2010.
[3] S. Yu, C. Wang, K. Ren, and W. Lou, “Achieving Secure,
Scalable, and Fine-Grained Data Access Control in Cloud
Computing,” Proc. IEEE INFOCOM, pp. 534-542, 2010.
[4] M. Kallahalla, E. Riedel, R. Swaminathan, Q. Wang, and K.
Fu, “Plutus: Scalable Secure File Sharing on Untrusted
Storage,” Proc. USENIX Conf. File and Storage Technologies,
pp. 29-42, 2003.
[5] E. Goh, H. Shacham, N. Modadugu, and D. Boneh, “Sirius:
Securing Remote Untrusted Storage,” Proc. Network
[6] M. Chase, „„Multi-Authority Attribute Based Encryption,‟‟
in Proc. 4th Theory of Cryptography Conf. Theory of
Cryptography (TCC‟07), 2007, pp. 515-534.
[7] M. Chase and S.S.M. Chow, „„Improving Privacy and
Security in Multi-Authority Attribute-Based Encryption,‟‟ in
Proc. 16th ACM Conf. Computer and Comm. Security
(CCS‟09), 2009, pp. 121-130.
[8] A.B. Lewko and B. Waters, „„Decentralizing AttributeBased Encryption,‟‟ in Proc. Advances in CryptologyEUROCRYPT‟11, 2011, pp. 568-588.
[9] S. Yu, C. Wang, K. Ren, and W. Lou, „„Attribute Based
Data Sharing with Attribute Revocation,‟‟ in Proc. 5th ACM
Symp. Information, Computer and Comm. Security
(ASIACCS‟10), 2010, pp. 261-270.
[10] M. Li, S. Yu, Y. Zheng, K. Ren, and W. Lou, „„Scalable
and Secure Sharing of Personal Health Records in Cloud
Computing Using Attribute-Based Encryption,‟‟ IEEE Trans.
Parallel Distributed Systems, vol. 24, no. 1, pp. 131-143, Jan.
2013.
[11] J. Hur and D.K. Noh, „„Attribute-Based Access Control
with Efficient Revocation in Data Outsourcing Systems,‟‟ IEEE
Trans. Parallel Distributed Systems, vol. 22, no. 7, pp. 12141221, July 2011.
SSN: 2231-5381
http://www.ijettjournal.org
Page 86