Understanding The Basic Concepts Of Voip Information Technology Essay

Cryptography is the art and scientific discipline of concealing secret messages within an unfastened bearer medium which ideally can non be detected by 3rd parties. More specifically, web cryptography is the method of accomplishing covert communicating by concealing secret informations within the normal informations transmittals of users. Audio is a good screen ” for covert communications, because it is further aided by the fact that the human ear is insensitive to little deformations in the audio signal. VoIP on the other manus, the latest popular method of reassigning sound, has become a natural mark for cryptography every bit good due to its built-in redundancy, therefore high concealed capacity.

Security issues

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Although information concealment was introduced in ancient Greece, today calculating has made cryptography accessible and convenient. The fact that free available steganographic tools can be put in the custodies of legitimate every bit good as non- legitimate users has raisedquestions and uncertainties sing the trade-offs of peculiar stairss taken in order to forestall the incorrect usage of cryptography. Network cryptography methods can be a menace to web security, as they may be used as a tool for confidential information escape. In order to develop countermeasures, it is of import to place possibilities for covert communicating and methods of concealing information. However, cryptography has benefits when used in digital rights direction and accomplishing private and anon. communicating.


No real-world steganographic method is perfect ; in fact the possibility of observing concealed information into the usually transmitted information additions comparatively to its volume. The countermeasure to cryptography is steganalysis. Steganalysis methods identify suspected web communicating and seek to find whether or non concealed information is carried. Furthermore, steganalysis can be an effectual manner to judge the security public presentation of steganographic techniques as good.

Audio cryptography categorization

Network cryptography may be classified into three wide groups:

Steganographic methods that modify packages ;

Steganographic methods that modify the construction of package watercourses ;

Hybrid steganographic methods

There different ways of implementing the 2nd group of methods- related to clip modification- such as reordering of packages, alteration of inter-packet hold and knowing loss of packages. By and large, the methods which affect the sequence order of packages and introduce knowing losingss are possible merely during the conversation stage of VoIP ( RTP: Real Time Protocol ) , while there are non utile during the signalling stage of VoIP ( SIP: Session Initiation Protocol ) due to the little figure of messages. The feature of those clip relation methods, comparing to the alteration of packages 1s, is the lower steganographic capacity but they are harder to observe. However, their drawback is the possible impairment of conversation quality.


By and large, steganalysis is difficult to execute because package loss in IP webs is natural, so knowing losingss that are kept on a sensible degree are non easy to observe. The purpose of this undertaking is to execute statistical steganalysis of lost packages by detecting the RTP watercourses flow and identify possible usage of cryptography in audio channels if for some of the ascertained calls the figure of lost packages is higher than norm.

Parameters like the size of the jitter buffer which play an of import function in the VoIP communicating between two terminals will be examined. RTP packages will be recognized as lost when the hold is greater than a certain threshold and this undertaking will seek to specify the lowest hold that limits the hazard of sensing of the concealed information. Codecs which are impacting the package loss and steganographic bandwidth will be examined every bit good. The chief thought is to make an active warden that will analyze all RTP watercourses both in WAN and LAN environments.

The scenarios which will be developed sing the effectivity of the steganographic method will hold as parametric quantities the:

* codecs

* size of voice frame

* receiving systems buffer

* webs QoS ( package hold, package loss chance )

Scenarios illustration

One manner of implementing VoIP cryptography during the conversation stage is the permutation of the voice warhead of RTP packages with steganograms. In usual multimedia communicating overly delayed packages are non used for Reconstruction of transmitted informations at the receiver terminal. Furthermore, RTP is normally integrated in telephone end points ( softphones ) so entree to RTP packages coevals and alteration is easier to execute than in the instance of lower bed protocols. If audio packages are deliberately delayed they will be discarded when they reach an incognizant receiving system. However, if the receiving system knows about the concealed communicating, so alternatively of canceling the package will pull out the warhead.

Technologies and Resources

For this undertaking will be used a set of hardware and package resources for implementing the testing and simulations.


2- 3 Personal computers back uping Windows and/or Linux runing systems

Software: the undermentioned list of package is unfastened beginning

Iperf: is a tool to mensurate the bandwidth and the quality of a web nexus

Wireshark: web analyser, provides web and upper bed protocols information about informations captured in a web

NS-2: a distinct event simulator targeted at networking research, written in C++ and an Object oriented version of Tcl

Softphones: i.e. X-Lite

VoIP proctor: unfastened beginning unrecorded web package sniffer and name recording equipment for Linux which analyzes SIP and RTP protocol

Wanem: emulate specific nexus qualities for proving the behavior of an application i.e. softphone

Software for statistical analysis: one of the already installed in the Kingstons IT Labs

Method and Work program

The simulations will be done by utilizing Kingston Universitys substructure and equipment, most likely in the Sopwith Building IT Labs. Once the simulations environment is set, the scenarios will be implemented and the informations will be collected and stored for analysis. Softphones will be used for imitating the VoIP Sessionss between two terminals. More specifically the different scenarios will be based on the fluctuations of:

Codecs: G.723.1, G.729A and G.711

Voice frame: different sizes of voice frames and RTP packages

Receivers buffer: the size of jitter buffer affects the determination of flinging overly delayed packages

Jitter buffer: The size of the jitter buffer at the receiving system is, in rule, unknown to the active warden, a method for acquiring this information at the beginning of a session will be examined and how it will impact the find of the covert channel.

The eventuality program includes a large pool of scenarios which can be implemented for roll uping and analyzing informations. The lone hazard that has been identified is that during the simulations, some of the scenarios might non be executable, nevertheless there are no human informations involved in the undertaking that will wipe out ethical issues.

Finally, the undertaking will adhere to the undermentioned clip graduated table to transport out the assorted undertakings.

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