Short Message Service (sms) security solution for mobile devices

c. Network 
Security 
The SMSC usually rides on the Internet infrastructure for cost 
reasons and to tap into the huge number of Internet users. By connecting to the 
Internet, the SMSC has essentially bridged the GSM network with the Internet 
and introduced the vulnerabilities and threats of the Internet to the GSM network. 
One can argue that many GSM operators already support General Packet Radio 
Service (GPRS), which is also connected to the Internet. However, the key 
difference is that the GSM operator owns the GPRS infrastructure. Therefore, the 
telecommunications operator can decide on what the defensive mechanisms are 
required to enforce the security policy. However, the GSM operator cannot 
mandate what mechanisms the SMSC must have in order to be connected to it.
 
C. 
SMS APPLICATION LAYER SECURITY 
1.
SMS Protocol 
The Short Message Service (SMS) was created as part of the GSM Phase 
1 standard. Each short message is up to 160 characters in length when Latin 
alphabets are used and 70 characters in length when non-Latin alphabets, such 
as Arabic and Chinese, are used [19].
SMS is a store and forward service. In other words, SMS messages are 
not sent directly from sender to recipient, but always via an SMS Center (SMSC). 
Each mobile telephone network that supports SMS has one or more messaging 
centers to handle and manage the short messages. Some of the features of 
SMS that have led to the popularity of SMS are [20]: 
•
SMS supports confirmation of message delivery. The sender of the 
message can choose to receive a return message back to indicate 
whether the SMS has been delivered or not. 
•
SMS can be sent and received simultaneously with other traffic. 
SMS uses the control channel as a transport mechanism, unlike 
voice, data and fax calls which use dedicated radio channels for the 
duration of the call.
•
SMS compression and concatenation have been defined and 
incorporated into the GSM SMS standards. As such, the original 
160 character limitation can be overcome.

---

 17
•
SMS is not bandwidth intensive. This allows telecommunications 
service providers to offer attractive pricing plans, which includes 
free SMS messages. Packages with 900 free SMS messages are 
offered for under USD20 in some service plans in Singapore [21].
Besides the technological properties, the attractive social aspect of short 
text messaging has also contributed to the success of SMS. Text messaging is 
non-intrusive and discreet, and is particularly suitable in certain social settings 
like meetings or social gatherings. Therefore, SMS has become the primary 
mode of communications for many. Besides the casual exchange of information 
among friends, the use of SMS has also expanded to other industries such as 
gaming, banking, education, remote sensor monitoring, advertising, voting, etc. 
Further potential applications using secure SMS are discussed in last Section of 
this Chapter.