Figure 4: The modified camera.
The equipment also has an integrated power
saving system that disables the LCD display, and
switches the processor in the energy saving mode
after a certain period of inactivity detected by the
included accelerometer and the user interaction with
the graphical interface (which is also monitored).
This time can be preferentially set by the user. The
reverse operations are executed also based on the
user interaction.
3 THE SOFTWARE
ARCHITECTURE
In terms of software, the system is installed with
Angstrom Linux operating system, the graphical
interface is generated by a system application that
runs under the X window system. When the device
is started, the system automatically searches for a
specific access point (or list of access points) to
which it connects using the security protocol Wi-Fi
Protected Access II (WPA2) to establish an Internet
connection (Wong, 2009, Kizza, 2009). If the access
point has not been found, the device allows the user
to manually configure the wireless connection
through the user interface.
After the Internet connection was made, the
system connects to a processing infrastructure that
will provide processing power and a database used
to store information about the enrolled users and
also provide information for personal identity
verification and identification.
The connection to the processing structure is
created using a VPN network which is based on the
IPsec technology (Internet Protocol Security see
Figure 5) (Red Hat Inc., 2007). IPsec is a software
solution to securely connect to a WAN; this solution
is widely used by top companies like Red Hat and
offers a high level of security for network
communications. IPsec is used to connect the mobile
device and the processing infrastructure using a
secure tunnel on a common carrier network such as
the Internet. IPsec uses Internet Key Exchange
(IKE), a protocol implemented by the Internet
Engineering Task Force (IETF) and used for mutual
authentication and secure associations between
connecting systems.
IKE uses X.509 certificates for authentication
which are either pre-shared or distributed using DNS
(preferably with DNSSEC), and a Diffie–Hellman
key exchange to set up a shared session secret from
which cryptographic keys are derived. In addition, a
security policy for every peer which will connect
must be manually maintained.
The IKE protocol uses UDP packets, usually on
port 500, and generally requires 4-6 packets with 2-3
turn-around times to create a Security Association
on both sides. The negotiated key material is then
given to the IPsec stack. For instance, this could be
an Advanced Encryption Standard key, information
identifying the IP endpoints and ports that are to be
protected, as well as what type of IPsec tunnel has
been created. The IPsec stack, in turn, intercepts the
relevant IP packets if and where appropriate and
performs encryption / decryption as required.
Implementations vary on how the interception of the
packets is done—for example, some use virtual
devices, others take a slice out of the firewall (in our
case IPsec uses virtual devices).
An IPsec connection is split into two logical
phases. In phase 1, an IPsec node initializes the
connection with the remote node or network. The
remote node or network checks the requesting node's
credentials and both parties negotiate the
authentication method for the connection.
In our case the IPsec connection uses the pre-
shared key method of IPsec node authentication. In a
pre-shared key IPsec connection, both hosts must
use the same key in order to move to Phase 2 of the
IPsec connection.
Phase 2 of the IPsec connection is where the
Security Association (SA) is created between IPsec
nodes. This phase establishes an SA database with
configuration information, such as the encryption
method, secret session key exchange parameters,
and more. This phase manages the actual IPsec
connection between remote nodes and networks.
IR LEDs
Visible
Light
Filter
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