Cryptography Reference
In-Depth Information
12
Application
s of Visual Cryptography
Bernd Borchert
Universitat Tubingen, Germany
Klaus Reinhardt
Universitat Tubingen, Germany
CONTENTS
12.1
Introduction :::::::::::::::::::::::::::::::::::::::::::::::::::::: 329
12.2
Trojan-Secure Conrmation of Transactions :::::::::::::::::::: 333
12.3
Trojan-Secure Authentication Using a PIN ::::::::::::::::::::: 334
12.4
Security versus Multiple Use ::::::::::::::::::::::::::::::::::::: 339
12.5
Using Refraction ::::::::::::::::::::::::::::::::::::::::::::::::: 343
12.6
Technical Problems Concerning Adjustment and Parallaxes :::: 346
12.7
Voting with a Receipt Based on visual cryptography ::::::::::: 347
12.8
Conclusion :::::::::::::::::::::::::::::::::::::::::::::::::::::::: 349
12.1 Introduction
Naor and Pinkas in their seminal paper [13] suggested to use visual cryptogra-
phy in a transparency-on-screen version. Their main purpose was authentica-
tion, in the sense that an online server is able to authenticate itself to a user
sitting in front of the screen. Implicitly, this already suggests the following
application of visual cryptography to the problem of manipulation of online
transactions, like online money transfers, by trojans:
Main Method. In order to secure online transactions, like online money
transfers, the user gets a numbered set of transparencies, each with a visual
cryptography pattern printed on it, from the transaction server. Now the
user is able to command online transactions in a secure way, see
Figure 12.1
as follows. He fills out an online form containing the data for the intended
transaction; in the case of a money transfer this would be the account number
and bank number of the destination bank account and the amount of the
money. This transaction data is submitted via Internet to the server. The
server does not execute the transaction immediately because in that case it
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