Cryptography Reference
In-Depth Information
10.4 Readable Code Methods
The readable code methods are the ways in which the URL of a website related
to a printed media is encoded into a machine-readable code. It is then printed
onto the paper with image samples.
Bar code is a traditional readable code that expresses numbers and charac-
ters with the combination of the bar and space. It is detected optically by
a read-machine. There are two kinds of bar code products, one is 1-dimensional
bar code that expresses the information with a number of linear bars and a
number of linear spaces. Another is a 2-dimensional bar code that arranges
the information in the two directions of length and width. Fig. 10.4 shows two
examples of bar code, a 1-dimensional and a 2-dimensional one.
Fig. 10.4.
Two examples of bar code, in which (a) is a sample of a 1-dimensional
bar codes called JAN Code, and (b) is a sample of a 2-dimensional bar codes called
QR Code (Quick Response Code).
Generally, the bar code is used as an input because of its e
ciency, accu-
racy and low cost. With the appearance of mobile phone cameras, it became
possible to use bar code as a method for the applications of print-to-web
linking technology using mobile phone camera. At present, the function for
reading a bar code has been widely supplied on mobile phones. It has become
a standard function of the mobile phone.
Compared with 1-dimensional bar codes, 2-dimensional bar codes can in-
crease the embedded amount of information 200 times or more. Since the
data embedded into 2-dimensional bar codes are enciphered, the security is
also improved. Therefore, 2-dimensional bar codes are more widely used in
mobile phones.
In addition to the bar codes, there are some other kinds of readable codes
that have been used for print-to-web linking technology. The methods of de-
veloping readable codes can be divided into 3 categories according to the
dimension or design of their constructions. They are as follows.
(1) One-dimensional bar code methods;
