Cryptography Reference
In-Depth Information
4
A Bit-Level Visual Secret Sharing Scheme
for Multi-Secret Images Using Rotation
and Reversion Operations
Chin-Chen Chang
1,2
, Tzu-Chuen Lu
2
, and Yi-Hsuan Fan
3
1
Feng Chia University, Taichung, Taiwan, 40724, R.O.C.,
ccc@cs.ccu.edu.tw
,
WWW home page:
http://www.cs.ccu.edu.tw/
∼
ccc
2
Chaoyang University of Technology, Taiwan, 413, R.O.C.
tclu@cyut.edu.tw
3
National Chung Cheng University, Chiayi, Taiwan, 621, R.O.C.
Summary.
In 1995, Naor and Shamir proposed a visual secret sharing scheme to
share a secret image with several participants. In this chapter, we extend the concept
of visual secret sharing to gray-scale image visual secret sharing. This chapter applies
the rotation and reversion operations to increase the security of the secret images
and the utilization of the shared shadows. The experimental results show that the
scheme can completely reconstruct the original gray-scale image, and the shadows
can be used to hide more secret images. In addition, the proposed scheme can be
extended to the application that some specific participants are only allowed to restore
a certain amount of secret information.
4.1 Introduction
Secret sharing is a very interesting and important issue for variance appli-
cations, such as secure key management, secret data protection, and so on.
In order to protect a secret file or text, we use a secret key to encrypt it.
However, if unauthorized people or even our members use the secret key to
decrypt the file, then the secret file is very likely to be stolen. Therefore, we
need a secret key management to protect the secret key. The secret sharing
system is a strategy formed to protect the secret key [1, 2].
Blakley [3] and Naor and Shamir [4] proposed their schemes for secret
sharing. In Naor and Shamirs scheme, a key, which can be used to access
many important files, is divided into several pieces, called shadows or shares.
Then, those shadows are distributed to different participants. Each participant
cannot retrieve any information from the shadow. When we need the key to
access a file, a subset of participants can collect their shadows and reconstruct
the key. A general secret sharing problem is t-out-of-n secret sharing. It is
