An anti-cheating block secret sharing scheme based-on Cyclic Codes
Xing-Fu Xu
1
Dao-Shun Wang
1
1
Department of Computer Science and Technology
Tsinghua University
Beijing, China
e-mail: gsxxf@sina.com;
daoshun@ mail.tsinghua.edu.cn
Shun-Dong Li
2
Ching-Nung Yang
3
2
School of Computer Science Shaanxi Normal
University Xi’an, China
3
Department of Computer Science and Information
Engineering, National Dong Hwa University, Taiwan
e-mail: shundong@snnu.edu.cn;
cnyang@mail.ndhu.edu.tw
Abstract—In secret sharing, cheaters may reconstruct and recover
the secret by providing faked shares, but the honest participants get
no information about it. The anti-cheating secret sharing scheme
can detect cheating and identify cheaters, so that it can effectively
resist cheating attacks. In this paper, we construct a Cyclic Codes-
based (k,n)-block secret sharing scheme against cheating. If there
are more than k participants reconstructing the secret, we can
detect cheating and identify cheaters. We discuss the relationship
between the length of the secret block and the computational
complexity, the length of the secret block and the storage space.
Also, we give the upper bound of the number of identifiable
cheaters. When there are no fewer than k honest participants, we
can identify all cheaters.
Keywords-block-secret sharing scheme; Cyclic Codes; anti-
cheating.
I. INTRODUCTION
Since secret sharing was proposed by Shamir [1] and
Blakley [2] independently in 1979, many researchers have
studied it [3-8]. However, the secret sharing scheme may be
subject to cheating attacks. M. Tompa and H. Woll [9]
consider there may be some cheater to reconstruct the secret
by presenting faked shares, and the cheaters may recover the
secret, but other honest participants get no information on it.
After that, there are lots of researches on secret sharing
schemes against cheating [10-16].
In the paper, we construct a
),( nk
-block secret sharing
scheme based-on Cyclic Codes and discuss the relationship
between the length of the secret block and the computational
complexity, the length of the secret block and the storage
space. According to the error detection and correction of
Cyclic Codes, we can detect cheating and identify cheaters in
the secret reconstruction phase of the proposed scheme. We
analyze the complexity of the anti-cheating algorithm and
give the upper bound of the number of identifiable cheaters.
This paper is organized as follows. Section II is the
introduction of preliminaries. In Sections III and IV, we
propose the anti-cheating block secret sharing scheme based-
on Cyclic Codes. In Section V, we give the comparison and
conclusion.
II. P
RELIMINARIES
Over the finite field ˈ any codeword can use a
polynomial representation. Such the polynomial is referred to
as code polynomial. For any codeword
],,,[
011
cccC
k
"
−
=
,
its codeword polynomial corresponds to
01
1
1
)( cxcxcxC
k
k
+++=
−
−
"
.
Over
)2(GF
, Cyclic Codes encoding process is as
follows [17].
Assume that a codeword is
],,,[
021
mmmmessage
ll
"
−−
=
,
so its codeword polynomial is
01
1
1
)( mxmxmxm
l
l
+++=
−
−
"
.
Select a degree
lkr −=
polynomial
)(xg
over
)2(GF
.
The constant term of
)(xg
is 1, and
)(xg
must be a divisor
of
1+
k
x
. Usually, it is called a generator polynomial.
Define
)(mod)()(
1
xgxmxxR
k −
=
, so the degree of
)(xR
is less than
lk −
.
)()()(
01
2
2
1
1
xRxmxcxcxcxcxC
lkk
k
k
k
+=++++=
−−
−
−
−
"
Over
)()2(
+
∈ ZdGF
d
, there is a codeword block
110
,,,
−
=
l
MMMM "
of the length
l
.
)1,,1,0(22
)0()2(2)1(1
−=+++×=
−−−−
ljMMMM
j
d
j
dd
j
d
j
""
.
For any
}1,,1,0{ −∈ di "
,
],,,[],,,[
)(
1
)(
1
)(
0021
i
l
ii
lli
MMMmmmmessage
−−−
== ""
. So the
codeword polynomial of
i
message
is
)(
1
)(
2
1)(
0
)(
i
l
i
l
li
i
MxMxMxm
−−
−
+++= "
.
We can get
0,1,
2
2,
1
1,
)(
)(
ii
k
ki
k
ki
i
cxcxcxcxC ++++=
−
−
−
−
"
by Cyclic Codes encoding, where
}1,,1,0{ −∈ di "
. Add
these
d
polynomials bit-level based, then we get
01
2
2
1
1
)( cxcxcxcxC
k
k
k
k
++++=
−
−
−
−
"
(1)
Where
1,,1,0,22
,0,1,1
1
−=+×++×=
−
−
kjcccc
jjjd
d
j
""
.
We use the formula (1) to represent the Cyclic Codes
polynomial of the codeword block
110
,,,
−
=
l
MMMM "
over
)()2(
+
∈ ZdGF
d
.
III. T
HE PROPOSED SCHEME BASED-ON CYCLIC CODES
A. The construction of scheme
According to Cyclic Codes encoding process, we can
construct a
),( nk
-block secret sharing scheme. Assume that
there is a secret block
],,,[
110 −
=
S
L
MMMS "
in length of
2013 Ninth International Conference on Intelligent Information Hiding and Multimedia Signal Processing
978-0-7695-5120-3/13 $26.00 © 2013 IEEE
DOI 10.1109/IIH-MSP.2013.99
369
2013 Ninth International Conference on Intelligent Information Hiding and Multimedia Signal Processing
978-0-7695-5120-3/13 $26.00 © 2013 IEEE
DOI 10.1109/IIH-MSP.2013.99
369