250
Maria Calagna and Luigi V. Mancini
the scaling factor of columns. If rows (columns) are mutually scaled, A
s has the
singular values σ i ∗
√
L r (σ i ∗
√
L c ).
11.5 Steganography for Spatial and Geographical Data
Steganography can be used to transmit secret information through digital maps in
which it is possible to slightly modify some elements, while preserving the quality
of the original map. Given such a capability, potential users of digital mapping with
the help of steganography can exchange information by means of maps, without
arising suspicion by unauthorized users. Also, they can agree on the representation
model and they are able to encode and decode information based on some criterion.
The strength of steganography is that the secret message is undetectable by those
who do not know the secret key; it was reported on USA Today 2001 that terrorists
embed information concerning possible targets in apparently innocuous images that
are exchanged in chat rooms.
In past years, the problem of transmitting secret messages bypassing conventional schemes has emerged. Research efforts have focused on the following two
different approaches:
1. Create a secure steganography scheme that can be employed to communicate
secretly (e.g. for military purposes).
2. Apply steganalysis techniques to detect illegal use of steganography.
We remind the reader that the aim of steganography is to conceal the transmission of extra information through innocuous vehicles. The robustness requirement
is not necessary since a potential adversary does not know about the existence of
any extra information that is carried secretly. Therefore, it is not necessary to prevent removal or distortion attacks that are directed at making the secret information
useless. Satellite images are becoming interesting for different classes of people. An
interesting approach concerns the addition of steganography to traditional satellite
or aerial images to make available different kinds of information to different classes
of users. What we have in mind is the possibility of adding some hidden content
that could be visualized properly only by authorized people. For example, a digital
map, produced from satellite or aerial observation, could be transferred by public
channel. Some people, such as public agencies employees, could be authorized to
receive highly detailed information that should be forbidden to unauthorized users.
For instance, consider a digital map with disease data or income amounts of families living in a specific area associated to it. Distribution of the digital map through
a public channel should prevent unauthorized users from having access to this kind
of information. In the military field, the addition of steganography to digital maps
may be employed to communicate secretly meeting points, base stations, the planned
route for traveling, and generally, additional information that should be maintained
as secret.
In the following section, we introduce a new conceptual GIS model that integrates public-key steganography with digital mapping. Some related work concerns
Maria Calagna and Luigi V. Mancini
the scaling factor of columns. If rows (columns) are mutually scaled, A
s has the
singular values σ i ∗
√
L r (σ i ∗
√
L c ).
11.5 Steganography for Spatial and Geographical Data
Steganography can be used to transmit secret information through digital maps in
which it is possible to slightly modify some elements, while preserving the quality
of the original map. Given such a capability, potential users of digital mapping with
the help of steganography can exchange information by means of maps, without
arising suspicion by unauthorized users. Also, they can agree on the representation
model and they are able to encode and decode information based on some criterion.
The strength of steganography is that the secret message is undetectable by those
who do not know the secret key; it was reported on USA Today 2001 that terrorists
embed information concerning possible targets in apparently innocuous images that
are exchanged in chat rooms.
In past years, the problem of transmitting secret messages bypassing conventional schemes has emerged. Research efforts have focused on the following two
different approaches:
1. Create a secure steganography scheme that can be employed to communicate
secretly (e.g. for military purposes).
2. Apply steganalysis techniques to detect illegal use of steganography.
We remind the reader that the aim of steganography is to conceal the transmission of extra information through innocuous vehicles. The robustness requirement
is not necessary since a potential adversary does not know about the existence of
any extra information that is carried secretly. Therefore, it is not necessary to prevent removal or distortion attacks that are directed at making the secret information
useless. Satellite images are becoming interesting for different classes of people. An
interesting approach concerns the addition of steganography to traditional satellite
or aerial images to make available different kinds of information to different classes
of users. What we have in mind is the possibility of adding some hidden content
that could be visualized properly only by authorized people. For example, a digital
map, produced from satellite or aerial observation, could be transferred by public
channel. Some people, such as public agencies employees, could be authorized to
receive highly detailed information that should be forbidden to unauthorized users.
For instance, consider a digital map with disease data or income amounts of families living in a specific area associated to it. Distribution of the digital map through
a public channel should prevent unauthorized users from having access to this kind
of information. In the military field, the addition of steganography to digital maps
may be employed to communicate secretly meeting points, base stations, the planned
route for traveling, and generally, additional information that should be maintained
as secret.
In the following section, we introduce a new conceptual GIS model that integrates public-key steganography with digital mapping. Some related work concerns