Selected Papers

Pictorial Guidelines for Secure Spaces
Shigeyoshi Iizuka†
Abstract
As a result of the recent spread of computer technology and rapid growth of the Internet, we now live
in an age when all kinds of information can be exchanged and processed at any time and in any place,including information of a highly confidential nature. We have therefore drawn up pictorial guidelines
for designing secure spaces in public work environments where users can handle personal information
securely.

1. BackgroundIn recent years, environments have been set up
where people can use information technology (IT)equipment such as personal computers (PCs) to carryon with their work while away from the office. These
include wireless LAN (local area network) hot spots
on city streets and in establishments such as rental
offices and Internet cafés. Furthermore, automatic
teller machines (ATMs) are being installed not only
in banks, but also in convenience stores, allowing
people to withdraw and deposit cash close to theirhomes. It is also becoming commonplace for shops toaccept credit cards for payment at the checkout. Inother words, all kinds of information can now beexchanged and processed anywhere and at any time,
including information of a highly confidential nature.
However, these developments are also exposing users
to dangers such as leakage or misappropriation of
their personal information. Of course, services of thissort are provided with robust security systems such as
encryption, digital certification, and authentication
technologies such as IC (integrated circuit) cards andbiometric authentication, so these services are secure
to use as far as their functions are concerned. But
what about the environments in which these services
are used? For example, have you ever found yourself
worrying about people catching a glimpse of the† NTT Cyber Solutions Laboratories
Yokosuka-shi, 239-0847 JapanE-mail: s.iizuka@lab.ntt.co.jp

28

ATM display on a busy sidewalk? In practice, it is difficult to use highly confidential information, such as
personal details, securely in public work environments that are open to anybody. Here at NTT CyberSolutions Laboratories, we are not only researchingand developing network architectures where ITequipment can be used in many different places, buthave also initiated a study of “secure space designtechnology” based on a recognition of the fact that it
is also essential to investigate physical spaces wherepeople can use these services securely [1].
2. Safety and security
The words “safety” and “security” can generally be
used interchangeably, but here we use “safety” tomean “freedom from harm, injury, or damage” anduse “security” to mean “freedom from uncertainty oranxiety”. Under what sort of conditions do people
regard themselves as being safe? There are definitions in common use that are agreed upon at least in
this field of study and within organizations. Specifically, these definitions are based on scientific standards and reasoning. On the other hand, although
security is strongly related to safety, it includes psychological factors that are not attained simply by
being safe (Fig. 1). The word security can be thoughtof as expressing a subjective feeling of security in thesense that somebody feels secure [2]. At NTT CyberSolutions Laboratories, research into techniques fordesigning secure spaces is centered around the psychological studies of users, focusing on their feelings
NTT Technical ReviewSelected Papersof security in different situations.
3. Related studies
This section reviews previous studies related to thedesign of work environments where users can handle
information with a feeling of security in terms ofphysical aspects associated with ergonomics andarchitecture [3] and psychological aspects associatedwith environmental psychology and proxemics(explained later).
3.1 Physical aspects
Figure 2(a) shows a posture suitable for working

Security is strongly
related to safety,
but not completelydetermined by it.
It includes
psychologicalfactors.

SecuritySafety
Technology platform

Fig. 1. Safety and security.

Inter-personal Intimate Personal
distance
distance distance

Suitable distance fordisplay equipment

920

Typicalrelashonship

300

30°
150

on a PC with a display that takes account of thehuman frame, build, and field of view. This figure
shows a desktop PC being used in a setup where theheight of the desk and chair, the position of the input
equipment, and the display can be independently
adjusted to maintain a posture suitable for work.
3.2 Psychological aspects
When we become concerned about other people
nearby, it is because we feel they have invaded ourspace. This “personal space” is an invisible spatial
region surrounding a person’s body. In general, people feel relaxed when their personal space is guaranteed and uncomfortable when it is invaded by others[4] (Fig. 2(b)) As a result of these feelings, people
tend to maintain a suitable distance from each other.
This concept was described by Edward T. Hall in his
theory of proxemics [5] (Fig. 2(c)). According to thistheory, a person’s distance from others indicates therelationship that exists between them and is categorized into four levels: intimate, personal, social, andpublic. It can also be seen that people move themselves further away from others, particularly ones
behind them, when they feel insecure. It can thus beinferred that when people are handling credit card
numbers or the like, it is particularly important toconsider what is going on behind them. Also, sincepartitions can be used to block visibility, they are suitable for keeping spaces private, making them indisSocial distance
Recognized as “others”

Public distance
Distance where escape is possibleLovers

FamilyBusinessmeeting

Conversation
with one’s boss

Speaker and audience

400

800

900

1400

4000

900

410

2–4°

780

200

100

Seating space

Leg room

550550(c) Proxemics(a) Visual display unit and work posture

Parsonal space (next to a male): Male approached by known male
: Male approached by unknown male
: Female approached by known male
: Female approached by unknown male
200(b) Personal space

Height of room
2500
2250
2000
Eye level when standing
1750
1500 Eye level when sitting
1250
1000
750
500
250
0
Privacy Region ofboundary no privacy

Region ofPrivacy maintainedTotal
partial privacy even when standing privacy(d) Relationship between privacy and partition heightFig. 2. Other studies related to the design of work environments (units: mm).

Vol. 3 No. 11 Nov. 2005

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Selected Papers

pensable environment elements in the construction of
personal PC operating environments in public spaces.
Privacy is also influenced by the height of partitions(Fig. 2(d)). For someone who is sitting down, forexample, a partition height that conceals another seated person from view can afford adequate privacy. The
minimum partition height that can provide this lowest
level of privacy among seated persons is about 1200mm.
4. Designing secure environments
In the design of work environments, as in the example shown in section 3.1, guidelines have alreadybeen shown from the viewpoint of the human form in
the fields of ergonomics and architecture. However,no research has been done from the viewpoint of how
secure users feel or what sort of information they are
dealing with. Consequently, there is a need for guidelines and methods relating to the design of shared
work environments where users can handle personal
information securely. At NTT Cyber Solutions Laboratories, we are therefore conducting research withthe aim of constructing high-security environments
based on the level of security that users feel whenhandling personal information in public work environments. A feature of this research is that we aredesigning work environments where users can feelsecure according to the type of personal information
they are dealing with. As mentioned above, the concept of security encompasses many psychologicalfactors. Our studies have therefore included psychological assessment of users, and we have conductedvarious cognitive experiments and analyzed theresults. In this way, we have extracted factors that
influence feelings of security, and we have calculated
various parameters for designing spaces according topeople’s feelings of security. Based on these results,
we have drawn up guidelines for the design of secureenvironments.
4.1 Extracting factors that influence security
To extract the factors that influence the feeling ofsecurity when working with information in public
environments, we investigated how resistant ordinary
users feel about handling personal information in
actual public work environments. As a result, wefound there are four personal information factors andfour work environment factors associated with users’
feelings of security in public work environments. Wealso produced a security level map (Fig. 3) that represents the level of security that people feel with eachcombination of these factors. In this figure, the size ofeach blue circle represents the level of security felt byWork environment factors∗

Private room of spacewith partitions highenough to block visibility
even when standing

SecureSpace with partitions highenough to block visibility
when sitting or to block
visibility to the terminal
screenAnxiousNo partitions around seats,
but with almost nobody
around. Private location
No partitions around seats,
and with some people
around, or observable bystaff
Information Information Information
Personal
related torelated torelated to identificationpreferences status/history
information andworkor activities
information
related to money
Personal information factors∗∗ Grouped into four categories based on similarities in thesecurity feelings of different users (cluster analysis)Fig. 3. Map of security feelings in public work environments.

30NTT Technical Review

Selected Papers

the user. For example, users feel very secure whendealing with information relating to preferences or
activities in a separate room or in a space surroundedby partitions that cannot be overlooked even bysomeone standing. On the other hand, they feel very
insecure (i.e., very anxious) when dealing with personal or financial details when sitting in an open area
where there are other people or staff nearby.
4.2 Drawing up guidelines
By conducting further studies, we identified four
personal information and work environment factorsthat influence people’s feelings of security: (i) partition height, (ii) partition thickness, (iii) type of information, and (iv) presence of others nearby. We also
clarified how tall and thick partitions should be andhow much distance should be provided behind users
for them to be able to handle different types of information with a feeling of security. By using theseresults together with the abovementioned findings ofour related research, we drew up pictorial guidelines
for secure spaces (Fig. 4).

In these guidelines, personal information is divided
into four categories based on how secure users feel
when using personal information in public work environments. Guidelines are then shown for the designof optimal work environments for each category.
Since these guidelines relate to the design of spaces,
they are depicted in the form of diagrams so that people can easily understand them visually. Specifically,
with regard to terminals installed in public spaces,
these guidelines stipulate the optimal partition sizes
and distances to be maintained from other people to
the rear for different information usage applications(i.e., for the handling of different types of information). They will lead to the creation of work spaces
where users can handle personal information securely. These guidelines are applicable to the design ofoffices as well as public work environments.
5. Future prospects
In the future, it is expected that many more types ofinformation will be handled in a wider variety ofWhen handling
When handlinginformation related to personal identification
information, informationpreferences orrelated to money,
activities
status, history, or work

Partition size
Height:400 Depth:
350

Height:500

Depth:
550

Secure distance to rear
(with no rear partition)

0Secure distance to rear
(with a rear partition)

01850

1700

Intimate Personal Social distancedistance distance (close phase)

3350

3000
Social distance(remote phase)

PublicdistanceFig. 4. Examples of pictorial guidelines for secure spaces (units: mm).

Vol. 3 No. 11 Nov. 200531

Selected Papers

places. To handle these changes, we must continue
with further studies of environmental factors andother factors that influence people’s feelings of security. We will continue in our efforts to clarify people’sfeelings of security (psychological characteristics)
and make use of this knowledge in the design ofsecure spaces. We will also apply the results of thisresearch to many more spaces to construct environments where ubiquitous services can be used securely. We hope to introduce these secure space guidelines to business companies and expand the importance and significance of secure space design.

Shigeyoshi Iizuka
Research Engineer, NTT Cyber Solutions Laboratories, Human Interaction Project.
He received the B.E. degree in mathematics
from Shizuoka University, Shizuoka in 1990 andjoined NTT the same year. He moved to NTT
Cyber Solution Laboratories in 1999. He is currently researching human interfaces. He is amember of the Human Interface Society, theInstitute of Electronics, Information and Communication Engineers of Japan, and the Information Processing Society of Japan.

References
[1]

[2]

[3]
[4]
[5]

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S. Iizuka, K. Ogawa, S. Nakajima, Y. Goto, and A. Watanabe, “Thesecurity of public terminal use in public spaces,” IPSJ Journal, Proc.
of the 66th IPSJ Annual Convention, pp. 4-451-2, 2004 (in Japanese).
T. Kikkawa, S. Shirato, S. Fujii, and K. Takemura, “The pursuit ofinformed reassurance (‘AN-SHIN’ in society) and technological safety (‘AN-ZEN’),” Social Technology Research Papers, Vol. 1.1, 1-8,
Oct. 2003 (in Japanese).
Architectural Institute of Japan, “Compact Building Design Reference Materials, 2nd Ed.,” Maruzen, 2003 (in Japanese).
S. Shibuya, “Comfortable interpersonal distances,” NHK Books,
1990 (in Japanese).
E. T. Hall, “The Hidden Dimension,” Misuzu Shobo, 1970 (in Japanese).

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