What is a transposition cipher method?

- The transposition cipher method is one of the cryptography methods used for securing the communication from eavesdroppers. 

- This method of encryption shifts the positions of the units or letters of the plain text based up on some regular system so that a permutation of the plain text is generated. 

- This permuted plain text is termed as the cipher text. 

- Thus, the cipher text is generated by changing the order of the units. 

- Mathematically the following functions are used:

Ø  Bijective function: For encryption of the character’s position and

Ø  Inverse function: For decrypting the message

Now we shall see about some of the implementations of the transposition cipher:

1. Rail fence cipher: 

- This form of the transposition cipher has been named so because of the way that it follows for encoding.

- Here, the characters of the plain text are written on the successive rails in a downwards manner of some imagined fence.

- Then, we move upwards once getting to the bottom. 

- For reading the message, it is taken in rows.

2. Route cipher: 

- In this form of transposition cipher, a grid of given dimensions is taken on which the characters of the plain text are written out. 

- Then, the message is read based up on the pattern mentioned in the key. 

- For example, the pattern might be inwards spiral in clockwise direction starting from topmost right.

- The route ciphers may use many keys unlike the rail fence cipher. 

- In fact, the number of keys used for enumerating the messages of reasonable length by modern machinery might be too great. 

- Also, it is not necessary that all the keys might be good in equal terms. 

- Excessive chunks of the plain text might be left if bad routes are chosen. 

- Also, the plain text might be simply reversed, thus giving a clue to the crypt analysts about the routes. 

- The union route cipher is a variation of the traditional route cipher. 

- The difference between the two is that this one transposed the whole words unlike route cipher which transposed individual letters.

- But since transposing the whole words could expose them, they were first hidden by a code.

- The entire null words might be added for adding humor to the cipher text.

3. Columnar transposition: 

- In this form of transposition cipher, a fixed length is determined for the rows in which the message is written. 

- But for reading the message a column by column approach is followed where some scrambled order if followed for choosing the columns. 

- A keyword is chosen which is used for defining the permutation of the columns as well as the width of the rows. 

- The spare spaces might be filled with the null characters in case of the regular columnar transposition. 

- On the other hand, in these spaces are left as such in the irregular columnar transposition cipher. 

- The keyword specifies some order following which the message is read column - wise. 

- The column lengths have to be worked out by the recipient for deciphering the message. 

- This is done based up on division of the length of the message specified by the key length.

4. Double transposition: 

- A single columnar transposition is vulnerable to attacks since the possible lengths of the column and anagrams can be guessed. 

- Therefore, a stronger version of it i.e., the double transposition is followed. 

- This is a two-time application of the columnar transposition. 

- For both the transpositions, either the same key might be used or different keys.

- This was the most complicated cipher before the coming of the VIC cipher. 

- It offered reliable operation under difficult conditions. 

What is a substitution cipher method?

There are two classic methods for cryptography namely transposition cipher method and the substitution cipher method. In this article we shall discuss about the latter one i.e., the substitution cipher method. 

- This method of encoding involves replacement of the units or letters of the plain text with some other units or letters. 

- The encoded text is then called as the cipher text. 

- The replacement of the units is made based up on some regular system. 

- These units might be individual letters, pairs or triplets of letters and so on. 

- On the receiver’s side, an inverse substitution is required for deciphering the text. 

- We can make a comparison between the transposition ciphers and the substitution ciphers. 

- In the former ciphers, the plain text units are rearranged unlike in substitution cipher where units are replaced.

- The order of rearrangement in the transposition ciphers is somewhat more complex than what is followed by the substitution ciphers and the units are not changed.

- On the other side, the sequence of the units remains same in the substitution cipher but they are themselves altered. 

There are various types of substitution cipher as mentioned below:

Ø  Simple substitution ciphers: 

- This involves substitution of the single letters and thus has been termed as the simple substitution. 

- The alphabet can be written out in some order so as to represent the substitution.

- This alphabet is referred to as the substitution alphabet. 

- This alphabet might be revered or shifted or scrambled in some complex manner. 

- In such cases, it is termed as the deranged alphabet or the mixed alphabet. 

- The creation of the mixed alphabets involves writing out a keyword while removing the repeating letters and then rewriting the leftovers in the same sequence. 

- For avoiding the transmission errors, the cipher text is written in block form and the spaces and the punctuation are omitted. 

- This also helps in creating disguises for the boundaries between the words.

Ø Homophonic substitution: 

- This method is followed for increasing the difficulty for the frequency analysis attacks. 

- The frequencies of the letters of the plain text are disguised by homophony. 

- Here the letters of the plain text are mapped to many symbols of the cipher text. 

- Normally the plain text symbols with highest frequencies are mapped with more equivalents when compared to their low frequency counterparts. 

- This leads to the flattening of the frequency distribution which in turn raises the difficulty of frequency analysis. 

- For the invention of larger alphabets a number of solutions are employed. 

- The simplest of these solutions is using a numeric substitution alphabet. 

- Another method uses the variations of the existing alphabet i.e., writing it upside down, or in upper case and lower case etc. 

- Nomenclature is also a variant of the homophonic substitution. 

- The other two types of homophonic ciphers namely straddling checker board and book cipher.

Ø Polyalphabetic substitution: 

- It involves the use of the multiple cipher alphabets. 

- For the facilitation of the encryption process, these alphabets are written out in a big table which is referred to as the tableau. 

- The particular poly alphabetic cipher is defined by the method with which the tableau is filled and the alphabet is chosen. 

- Some types of the polyalphabetic ciphers are:

             1. Beaufort cipher

             2. Gronsfeld cipher

             3. Running key cipher

             4. Autokey cipher

Ø  Polygraphic substitution: 

Here the letters of the plain text are substituted in terms of large groups instead of individual letter substitution.

Ø Mechanical substitution ciphers: 

Some examples of this type of substitution ciphers are enigma, rotor cipher machines etc.

Ø The one-time pad: 

This one is a special substitution cipher which has been proven that it is unbreakable mathematically.

What are the risks and liabilities with instant messaging?

There are a number of risks and liabilities associated with Instant Messaging. Till today several attempts have been done in order to create a unified IM standard. 

Few have been mentioned below:

1. Session initiation protocol or SIP of IETF.
2. SIP for instant messaging and presence leveraging extensions or SIMPLE.
3. APEX or application exchange.
4. IMPP or instant messaging and presence protocol.
5. XMPP or open XML – based extensible messaging and presence protocol.
6. Instant messaging and presence service of open mobile alliance (this one was developed exclusively for the mobiles.)

Although a number of benefits are given by instant message, there are also many risks and liabilities associated with it. This happens particularly when one uses IM at his/ her workplace. 

Associated risks and liabilities are:

1. Security risks
2. Inappropriate use
3. Compliance risks
4. Trade secret leakage

About Security Risks

- Security risks involve infecting the systems with viruses, worms, spyware and Trojans etc.

- Hackers and crackers make use of IM vectors for making phishing attempts, introducing the file attachments laden with virus and poisoned URLs. 

- Two main methods are used by the hackers for delivering the malicious code via instant messaging:

1. Delivering viruses, spyware or Trojan horses through an infected file.
2. Using the socially engineered text that has a web address enticing the recipient to go to an URL that in turn connects him/ her to a malicious website.

- The first kind of means i.e., the Trojans, worms and viruses propagate themselves by infecting the whole contact list of the user. 

- An attack done through means of a poisoned URL may infect 1000s of user’s system in a very short duration i.e., just when each of the person in the user’s contact list receives a message that appears to be from a trusted source. 

- Thus, when the recipients click on the web address, the whole cycle repeats. - Such infections might be for some criminal or a nuisance reasons. 

- These attacks are getting more sophisticated with time. 

- The connections in the instant messaging are usually in plain text. 

- This is what that makes them vulnerable to threats such as eavesdropping. 

- Also, with instant messaging, the UDP ports are left exposed to the world inviting many potential security vulnerabilities and raising many security issues.

About Inappropriate Use

 

- All the organizations, be of any type need protection against the liability of the inappropriate use of the IM service by the employees. 

- The nature of the IM, be it immediate, informal or anonymous marks it as an abuse of the workplace. 

- In a number of nations, a legal responsibility has been set up by the corporations in order to make sure that the working environment is free of any harassment for the employees. 

- Instant messaging is now included as an integral part of the policies of the companies regarding the appropriate use of services such as e – mail and world wide web and some other corporate assets.

About Compliance Risks

- Using the IM services at workplace also induces a risk concerning the non – compliance to laws and regulations that govern the use of electric communications. 

- The need for the production of the archived business communications that would satisfy the judicial requests is what to which most of the common regulations is related to. 

- There are a number of IM communications falling under the category of business communications and are retrievable. 

What are benefits of instant messaging?

Instant messaging comes with both risks and benefits. Here we focus up on its benefits.

Benefits of Instant Messaging

1. IM serves to be of great advantage in the environments that are geographically dispersed. The major benefit here is that it cut downs on the cost of expensive phone calls.
2. The communication channels can be augmented with the help of instant messaging. This will become clear from the following: suppose there is a conversation going between an external client and the team members can converse within themselves using IM for clarification of some points or plotting a strategy. Here, the IM is said to serve as a back channel.
3. IM serves as an efficient tool for clearing up the clutter on desktop and lets you respond immediately. Most of the business processes are time sensitive: problem resolution, crisis management, customer service etc. to name a few. IM is the solution for all these processes.
4. IM serves well in case of an emergency. The critical information can be rapidly disseminated to the whole company or individuals in cases such as that of health issues. Natural catastrophes, schedule changes, or network outages etc. most of the times, the network of IM services works well when most of other e – mail and phone networks are down.
5. A number of work groups can be linked through IM. Thus, it acts as a bonding between the two groups. The productivity of the ad-hoc contacts can be increased by enabling them to be quickly added to some work group.
6. IM services can also be used for routing the IMs to cell phones through the IM – to – SMS (short messaging service) gateway services. An example of such a service is find – me service.
7. Through IM services people have a quick reach to the experts if they want to survey multiple consultants or to have an instant consultation.
8. IM is a sort of self–service. People can place queries to the human resource virtual agents via person to machine IM services for obtaining information regarding enrollments or benefits. This also provides the staff with access to the data and speeds up the business processes.

More about Intant Messaging

- IM is one of the few small things that are a must for the effective communication 

- However, IM is embraced as a useful utility at workplace by some owners of small businesses. 

- IM services have been used to completely replace the traditional methods of communications or to provide support them. 

- IM is also a real – time means for communication. 

- But the text records of the IM conversations are kept by the exchange just as in the case of e–mail messages.

- This lets the IM function as a quick conference call without having the employees leave their desks. 

- It acts as a powerful means for bringing all the people on a web page common to all.  

- IM is an effective tool for conducting group chat. 

- Nowadays, such IM platforms that allow for group text chatting. 

- Plus, they also allow you to save the chat history. 

- Team members that are at some off- site locations can be connected through IM. 

- Through IM it becomes easy to stay connected and archive files.

How Instant Messaging Works?

Instant Messaging or IM is a very popular trend among all these days. A number of instant messaging services today offer features such as web conferencing, voice over IP and other video calling features. With such features both the IM features and video calling abilities can be integrated. 

About Working of Instant Messaging

- Each IM service has its own client that may be either a browser based client or some separate piece of software.

- These clients typically work with their sole company but some are designed in such a way that they support other services also. 

- There are some other third party clients that can connect with a number of major IM services. 

- Few such examples are Miranda IM, Trillian, Adium and so on.

- The IM program installed on your system connects to the IM Company via internet. 

- Here the user’s identity is verified. This process is termed as authentication. 

- After verification, the information or the ‘messages’ can be start exchanging between the users. 

- This IM program installed on your system is called the IM client. 

- When you start it up, it connects to the IM server of its company. 

- To log in to the IM service, you need to have an user ID and password. 

- Once they are verified to be correct, you are logged in. You are connected to the IM network. 

- A list of your friends who are currently online will be displayed. Your list will be changing as per who all are signing in and out. 

- People might have set different IM status such as ‘online’, ‘offline’ or ‘busy’ etc. when you type a message to your friend and hit enter; this message reaches him after traveling from your IM client through the IM server to which it is connected.

- The messages you send reach directly to your friends. 

- A pop up IM window displays your message to them. 

- As the chat progresses further, the messages travel to and fro between the two clients with very less delay of time. 

- Consider sending a file to your friend. You attach the file to the text and press enter. 

- Then your IM client will place an inquiry at the IM server to know the status of your friend. 

- If your friend is connected to internet, a direct connection to his IM client is established.

- The reason for using a direct connection is that it is much faster and efficient rather than sending files through a number of intermediate servers in case of an indirect connection. 

- Also, using a direct connection saves on bandwidth. 

- Instant messages are quite small in size and messages of a whole month may sum up to only 1 megabyte that is quite a tiny amount of space.

- This also enables instant messaging services to work equally on slow as well as fast internet connections.

How Inter-operability is supported by Instant Messaging?

- An instant messaging service can support a number of simultaneous conversations. 

- These are small applications that can cater to only small business needs. 

- But for larger organizations more sophisticated applications are required that can work in cooperation. 

- The enterprise versions of these applications provide solution to these problems.

- Some examples of larger IM applications are:

1. XMPP
2. Lotus same time
3. Microsoft office communicator and so on.

- These applications can be integrated with the workflow systems.

- These applications are also known as EAI or enterprise application integration as per certain constraints such as data storage in a specified format. 

- Several attempts have been made for creating a unified standard. 

What is meant by Instant Messaging?

Almost everyone today is familiar with the term ‘Instant messaging’ or IM in short. 

- This is a type of communication that sustains over the internet and quickly transmits the text based messages between people (i.e., senders and receivers). 

- The basic purpose of IM is to provide “real time direct written language–based online chat”. 

- It does this through push mode and other shared clients between two or more people using personal communication devices (mobiles) and personal computers. 

- A network such as the internet is used for conveying the text message for the person it is intended for. 

- IM addresses two kinds of communications namely:

1. Point – to – point communications i.e., from one person to another one person.
2. Multicast communications i.e., from one sender to a number of receivers.

- Nowadays, much enhanced modes of communication have been introduced by advanced instant messaging services. 

- Some enhancements are inclusion of video chat, audio calling and hyperlinks to other media etc. 

- The umbrella term is the online chat under which the concept of IM falls. 

- The similarity between them is that they are text based, happens in real time and offer bi – directional flow of messages. 

- The only distinction is that the IM is based up on clients. 

- The connections between the known users are facilitated by these clients only through a contact list (also known as friend list or buddy list).

- On the other hand, chat works up on web – based applications that facilitate communication between multiple users.

- A number of communication technologies that facilitates text based communication are combined together to provide the service of instant messaging. 

- The biggest feature of the IM – chats is that they take place in real time just like a phone call. 

- IM is different from the other web services such e–mail in the sense that users here perceive the “quasi – synchronicity of the communications”. 

- In IM, you can message only those people who are online at that time. 

- However, there exist some systems that allow you to message offline people, thus drawing some similarity between e–mail and IM.

- IM is cheap and effective means for efficient communication. 

- It allows immediate receipt of the message and also enables us to reply back immediately. 

- However, it is not necessary that the transaction control might support the IM. 

- In some cases there are additional features that make IM more interesting as mentioned below:

1. Enabling users to see each other via web cam.
2. Using headphones and microphones and talk for free over internet.
3. File transfers
4. Saving a text conversation for future reference.

- Instant messaging came much before the internet and first appeared on systems such as multics (multiplexed information and computing service) and CTSS or compatible time sharing system which are multi – user systems. 

- Some of the IM services such as ytalk, talk, ntalk and so on, peer – to – peer protocol.

- Some other examples of early IM services are:

1. Zephyr notification service
2. Bulletin board system or BBS
3. Freelancin round table
4. Compuserve CB simulator: this was the first dedicated online chat service

- Real time text was also a feature of these early instant messaging services.   

- AOL’s real time IM implements the modern real time text feature as an optional feature. 

- Video calling features such as web conferencing services can integrate both IM abilities and video calling.

How to add and match defects in Test Director?

Location of the defects and their effective repair forms an inseparable part of the application development and indeed of the test director testing process. Defects can be submitted by almost everyone involved with the development process such as the developers, end users and of course testers. The test director eases all the testing processes and thus defects can be submitted through it and can be tracked until they are appropriately repaired. 

In this article we shall discuss the following two things:

1. Adding defects in the test director and
2. Matching defects in test director

Steps in adding defects in Test Director

Whenever a defect is submitted to the test director it is processed through the following  four stages:

1. New
2. Open
3. Fixed
4. Closed

Addition of the defects to the test director can be carried out at almost any stage of the test process. Below we state the steps that you need to follow in order to add the defects in test director:

1. Open the test director project with which you are concerned and log on to it.
2. Next step involves displaying the defects module by clicking on the defects tab. The defect data will be displayed by the defects grid in a grid where each row is a representation of an individual defect record.
3. Clicking on the add defect button will open up the ‘add defect’ dialog box. The fields displayed in red color are mandatory to be filled up.
4. Fourth step involves describing the defect by providing the following details:

a) Summary: i.e., what problem the defect actually caused.

b) Category

c)  Severity

d) Subject

e) Detected in version

f) Description:

It includes the part of the code where the defect was discovered and 

what problem was actually encountered.

5. Now you need to attach the URL address for the page where the defect was found by clicking on the Attach URL button. Clicking on that button will open up a attach URL dialog box. There type the address of the page and click OK. This URL will be displayed above the description box by the test director.
6. Next run a spell check for the text in the description box. If any errors are found follow the replacement suggestions.
7. Click on the submit button to submit the defect to the test director project.
8. Finally, close the add defect dialog box by clicking on the close button. The defect will be added to the defect grid.

How to match defects in Test Director

- The purpose of matching the defects is to find similar defects so that the duplicate ones can be eliminated from the project. 

-  Every time a new defect is added the list of keywords is stored by the test director from the description and summary fields. 

-  The stored keywords are then used for matching the defects. 

- Articles, coordinate conjunctions, wildcards and Boolean operators are ignored by the test director while matching the two tests. 

- Below mentioned steps are for matching defects in test director:

1. Like for adding the defects this also requires displaying the defects module. Do this by clicking on the defects tab.
2. From the defects grid select the one you want to match. If in case you cannot find the required test search it using the clear filter/ sort button.
3. Now click on the find similar defects button to find similar defects. The results will be displayed in the similar defects dialog box by the test director.The defects are searched based up on percentage of the similarity detected.
4. Finally, click on the close button to close the similar defects dialog box. 

Explain the check points in QTP? In how many ways we can add check points to an application using QTP?

Check points in quick test professional have always proved to be an efficient tool. In this article, we discuss exclusively about the check points in quick test professional and the ways in which the check points can be added to an application with the help of quick test professional. 

What is Check Point? How it is added to an application?

- Check point can be thought of as a point to confirm or verify whether the application under test or AUT is working properly or not. 

- This is verified by making comparisons between the current value of some property and the expected value of the same property decided earlier. 

- Whenever a check point is added by the user, an equivalent check point is added by the quick test professional to the present row in the key word view as well as a “check check point” statement is added to the expert view. 

- The name of the test object also serves as a name for the check point that has been added to it. 

- The check points can be added via an active screen by placing the cursor on the desired location and clicking the insert standard check point option. 

Types of Check Points

It is on the basis of this expected value that the check points have been classified in to various types as described below:

1. Page check point: 

- This check point is the check point that is created exclusively for a web page. - This check point keeps a count of all the images and links present on that particular web page. 

- Another purpose for which page check point is used for checking the time taken by the web page to load fully i.e., the load time.

2. Bitmap check point: 

- This check point is the check point that helps in checking of the bitmap of either a full web page or an image. 

- Two images are provided to this check point, one the actual image and the other one expected image. 

- These two images are compared pixel by pixel by the bit map check point.

3. Image check point: 

- This check point is used for keeping a check on certain properties belonging to a web page such as the source file location of the image. 

- However, being a image check point, it cannot check pixels of an image like a bitmap check point does.

4. Text check point: 

- This check point is the check point that is employed in checking the expected text in a web application or web page. 

- This text may belong to a specific region of the text displayed or application under test.

5. Accessibility check point: 

- This check point verifies whether or not the accessibility standard of the application under test matches with the accessibility guidelines laid down by the W3C or world wide web consortium for information systems and technology which are web based.

6. Data base check point: 

- This check point performs the task of generating a query while the recording is in progress. 

- The values stored in the data base serve as expected values. 

- This query is executed during the run time to obtain the actual value which is then compared with the expected value.

7. Table check point: 

This check point is the one that is used for checking various table properties such as cell width, row width and so on.

8. XML check point: 

This check point is the one that is used to verify the following:

a)     XML schema

b)     XML data etc.