GSM
MODEM
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It is a special type of modem which accepts SIM card.
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These GSM modem are more frequently used to provide mobile connectivity.
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Many of them can also be used for sending and receiving SMS.
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In this case we are using GSM modem for sending the message only.
GSM
was intended to be a secure wireless system. It has considered the user
authentication using a preshared key and challenge-response, and over-the-air
encryption. However, GSM is vulnerable to different types of attack, each of
them aimed at a different part of the network.
The
development of UMTS introduces an optional Universal Subscriber Identity Module
(USIM), that uses a longer authentication key to give greater security, as well
as mutually authenticating the network and the user, whereas GSM only
authenticates the user to the network (and not vice versa). The security model
therefore offers confidentiality and authentication, but limited authorization
capabilities, and no non- repudiation.
GSM uses several cryptographic
algorithms for security. The A5/1, A5/2, and A5/3 stream ciphers are used for
ensuring over-the-air voice privacy. A5/1 was developed first and is a stronger
algorithm used within Europe and the United States; A5/2 is weaker and used in
other countries. Serious weaknesses have been found in
both algorithms: it is possible to break A5/2 in real-time with a
ciphertextonly attack, and in January 2007, The Hacker's Choice started the
A5/1 cracking project with plans to use FPGAs that allow A5/1 to be broken with
a rainbow table attack. The system supports multiple algorithms so operators
may replace that cipher with a stronger one.
Since 2000, different efforts
have been done in order to crack the A5 encryption algorithms. Both A5/1 and A5/2
algorithms are broken, and their cryptanalysis has been considered in the
literature. As an example,Karsten Nohl developed a number of rainbow tables
(static values which reduce the time needed to carry out an attack) and have
found new sources for known plaintext attacks. He said that it is possible to
build "a full GSM interceptor...from open-source components" but that
they had not done so because of legal concerns. Nohl claimed that he was able
to intercept voice and text conversations by impersonating another user to
listen to voicemail, make calls, or send text messages using a seven-year-old
Motorola cell phone and decryption software available for free online.
New attacks have been observed
that take advantage of poor security implementations, architecture, and development
for smart phone applications. Some wiretapping and eavesdropping techniques
hijack the audio input and output providing an opportunity for a third party to
listen in to the conversation.GSM uses General Packet Radio Service (GPRS) for
data transmissions like browsing the web. The most commonly deployed GPRS
ciphers were publicly broken in 2011.
The researchers revealed flaws in
the commonly used GEA/1 and GEA/2 ciphers and published the opensource "gprs
decode" software for sniffing GPRS networks. They also noted that some
carriers do not encrypt the data (i.e., using GEA/0) in order to detect the use
of traffic or protocols they do not like (e.g.,Skype), leaving customers
unprotected. GEA/3 seems to remain relatively hard to break and is said to be
in use on some more modern networks. If used with USIM to prevent connections
to fake base stations and downgrade attacks, users will be protected in the
medium term, though migration to 128-bit GEA/4 is still recommended.
Camera
Wireless security cameras are
closed-circuit television (CCTV) cameras that transmit a video and audio signal
to a wireless receiver through a radio band. Many wireless security cameras
require at least one cable or wire for power; "wireless" refers to
the transmission of video/audio. However, some wireless security cameras are battery-powered,
making the cameras truly wireless from top to bottom.
Wireless cameras are proving very
popular among modern security consumers due to their low installation
costs(there is no need to run expensive video extension cables) and flexible
mounting options; wireless cameras can be mounted/installed in locations
previously unavailable to standard wired cameras. In addition to the ease of use
and convenience of access, wireless security camera allows users to leverage
broadband wireless internet to provide seamless video streaming over-internet.
Digital wireless is the
transmission of audio and video analog signals encoded as digital packets over
high bandwidth radio frequencies.
Advantages include:
● Wide
transmission range—usually close to 450 feet (open space, clear line of sight
between camera and receiver)
● High
quality video and audio
● Two-way
communication between the camera and the receiver
● Digital
signal means you can transmit commands and functions, such as turning lights on
and off.
● You
can connect multiple receivers to one recording device, such as security DVR
Wireless
Range
Wireless security
cameras function best when there is a clear line of sight between the camera(s)
and the receiver. Outdoors, and with clear line of sight, digital wireless
cameras typically have a range between 250 to 450 feet. Indoors, the range can
be limited to 100 to 150 feet. Cubical walls, drywall, glass, and windows
generally do not
degrade wireless signal strength. Brick, concrete floors, and walls degrade
signal strength.Trees that are in the line of sight of the wireless camera and
receiver may impact signal strength.
NEXT COMING:::PERSONAL COMPUTER,WORKING,ADVANTAGES & DISADVANTAGES,APPLICATIONS,CONCLUSION
