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3.2.6.2
 
Discovering the Charging Control 
The Charging Control is discovered by the TMMS PR, or any other entity which needs 
to discover it, by issuing a query to the Domain Name System (DNS) [37] server in the 
network and querying for the “_CHRGCTRL” SRV RRresource ecord (RR), which 
follows [1]. 
Note that [1] requires a protocol specification describing this SRV RR in its 
“Applicability Statement” section. However, this is out of scope for this report. 
3.2.6.3
 
Charging Data Record (CDR) 
A CDR is a well-formed XML document, conforming to the XML Schema found in 
Appendix B:charging-details-record.xsd. It contains information about the sender, proxy-
relay, receiver, Charging Control and the message itself. By using all or parts of this 
information the operator can implement various charging schemes at the Business 
Support entity. 
The CDR contains one or more elements describing the media included in the message. 
Each element is described with its MIME/type and a count of how often it is included in 
the message. Optionally a price per such media element may be included, which is useful 
for a multimedia-delivery service. 

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3.3 TMMS Service based on GPRS: : Evaluation 
Page 40 of 93 
3.3
 
Evaluation 
3.3.1
 
Security 
Table 3-1: Evaluation of Security quality attribute for TMMS Service based on GPRS 
S1: Service is available for legitimate use and sustains Denial of Service attacks 
Availabili
ty
 
Client needs to get in contact with the nearest TMMS PR. This can be done in 
two ways. Option one is to set the PR’s IP address manually. The other option is 
to use DNS.
 
No security precaution is implemented to take care of Denial of Service attacks in 
the service. 
S2: Data is not altered during transmission 
Integrity 
No end-to-end data integrity check, such as checksums, is done to ensure that 
data is not altered. The client needs to trust the service. 
S3: Sender and receiver confirms that they are who they claim to be
Authentication 
The sender is authenticated with the TMMS PR, so given that the receiver trusts 
the TMMS PR it can also be sure that the message received comes from the 
claimed sender. 
S4: Only authorized users get access to the service 
Authorization 
The TMMS PR has a database which contains all authorized clients, which is 
queried when a client authenticates with it. In this way the TMMS PR can ensure 
that only legitimate users can access the service. 
S5: Only sender and the intended destination part is able to know the content of 
the message