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|Profile: I am a sophomore student at AIT, studying for my Bachelor’s degree in Computer Information Systems, affiliated to Tarleton State University, Texas. I am very interested in Programming and love getting involved in computer related topics which involves a lot of research and then a presentation of those topics.
I have knowledge about C, C++, Java, HTML and now MySQL, Visual C++ which includes windows programming, PHP and ASP. I am enjoying it.
Other than that, my interests include playing Volley Ball and other outdoor games. But my passion is Basketball. Well following my interest and passion, I along with Gunjan are making a database on NBA (National Basketball Association) as our project for Information Systems and Database Systems.
Prof. Ashay Dharwadker's Courses (2):
|Seminar ID: 43|
Course: Information Systems
Topic: The Enigma Cipher
|Description: Gunjan and I gave a seminar on Enigma Cipher. We started by giving an introduction to Substitution Cipher |
Substitution Cipher : It involves substituting one letter for another according to some rule. This is the principle underlying the Enigma. An example of substitution is :
Enigma Machine :- The Enigma Machine was invented in 1918 by Arthur Scherbius in Berlin. It enciphers a message by performing a number of substitutions one after the other. Scherbius's idea was to achieve these substitutions by electrical connections.
# The voltage appearing at the M terminal carries on to the R terminal on the bottom row. Thus the wirings have achieved a 'substitution' first from Q to M and then from M to R.
** The weaknesses in the machine: (which were much exploited and taken advantage of , by the Polish people to break into Enigma)
- 1. No letter can ever encipher to itself.
|Research Note ID: 38|
Course: Database Systems
Topic: Data Integrity
|Description: “Data Integrity, is a condition that exists when data has not been accidentally or maliciously modified, altered, or destroyed in an unauthorized manner. In order to maintain data integrity during operations such as transfer, storage, and retrieval and to ensure preservation of data for their intended use, several threat types must be addressed by policy, practice, and/or security technologies.” |
Data Integrity protection is vital to any computer. Loss of data integrity can cost huge amounts of time and money. Data integrity is ignored by most people, yet almost every computer suffers from loss of data integrity or in other words undetected corruption of its data. Sometimes this damage causes complete loss of a disk but mostly such damage’s goes unnoticed or the user simply reinstalls some of the software on their PC and this fixes the minor problem’s they were facing. But in some cases the user have to format the whole disk which cause lots and lots of inconvenience as well as consumption of time and money to recover the lost data.
Such problems may originate due to hardware defects, software errors, poor design concepts, internal component and telecommunications interference (noise), Unintentional Human Threats, Intentional Human Threats etc etc. To avoid such loses some users have tools like INTEGRITY MANAGER that can detect data corruption. PC tech support will often advice you to format the disk or reinstall software but with good data integrity protection, such drastic steps are not needed and hardware or software problems can be detected before they cause any serious damage to the disks. The key is that it's vital to have a way to make sure those programs and data you have on your PC are healthy. A good integrity checker can provide this assurance and can prevent major loss of data.
Most system managers rely on basic precautions such as a properly sized, uninterruptible power source (UPS) and instituting an offline data backup program to protect against data integrity problems resulting from hardware, software, and/or communications systems failures.
For situations where businesses cannot afford to risk the integrity of their data, they protect there data integrity by purchasing some specialized equipment which can provide additional protection to there valuable data. Systems are available, usually at increased cost, that deploy parallel processors that crosscheck each other’s output and perform end-to-end checksums on all data being transported.
The most common threat which may cause some serious problems is Unintentional Human Threats. Users who want to simply view a file but are unfamiliar with read-only viewing tools may revert to using file editors. When editors are used to view data, it is very easy to unintentionally delete or modify characters while reading a file. When deleting files, extreme care must be taken to not delete some files by mistake. This is especially true when using a wild card command. If, for example, in order to delete files abc001.dat through abc009.dat, the command “delete abc*.dat” is used, a file that should be retained called abcde.dat will also be deleted. Selecting the wrong backup tape, when doing a file restore, is a common way to corrupt data, as well.
Intentional Human Threats—Intentional human threats are, unfortunately, not limited to external perpetrators. Dissatisfied or dishonest employees with access privileges and knowledge of the target system(s) pose significant threats that are much more difficult to detect.
Prevention—the following simple precautions can significantly reduce the chances of experiencing data integrity problems.
- 1.Back up data and other software resources on a regular schedule, and store current copies at a secure off-site location.
- 2.Avoid using freeware or any other software that does not originate from a trusted source.
- 3.Back up data at intervals determined by the length of the recovery process.
- 4.Always use up-to-date virus protection software.
- 5.Have a properly maintained UPS and power-conditioning equipment operational at all times.
- 6.Enable auto-save features in system software and utilities, when available.
- 7.Implement and maintain auditing/detection tools capable of detecting and reporting changes to mission critical system files.
|Research Note ID: 49|
Course: Information Systems
Topic: Complexity of the Enigma Machine
|Description: The basic 3-rotor Enigma has 26x26x26 = 17,576 possible rotor states for each of 6 wheel orders giving 6x17,576 = 105,456 machine states. |
For each of these the plugboard (with ten pairs of letters connected) can be in 150,738,274,937,250 possible states.
Counting the Possible Plugboard Settings
The exact figure for settings of the plugboard with 10 pairs of letters connected is 150,738,274,937,250.
To see how this is worked out,basic facts about permutations and combinations are given below:
• Given n distinct objects there are n! ways of arranging them in sequence, where n! means the product n x (n-1) x (n-2)... 3 x 2 x 1.
For example the six digits 1,2,3,4,5,6 can be arranged in 6 x 5 x 4 x 3 x 2 x 1=720 different orders (bell-ringers will be familiar with this.)
• Given a set of n distinct objects there are C(n,r) ways of dividing it into two sets of size r and (n-r), where C(n,r) means
n! / r! (n-r)!
In the Enigma plugboard problem, the 26 letters have to be divided into 6 unpaired letters and 10 pairs of pairwise connected letters. One way of doing this is as follows: suppose that we had ten differently coloured connecting wires: red, blue, green etc etc.
Then there are C(26,2) ways of choosing a pair for the red wire. For each of these there are C(24,2) ways of choosing a pair for the blue wire, and so on, giving the product.
C(26,2) x C(24,2) x C(22,2) x ... x C(8,2)
This can be simplified, with many factors cancelling, to
26! / (6! 210)
But in the actual Enigma the wires are not coloured. This means we must divide by the number of ways of permuting the 10 coloured wires, i.e. divide by a further factor of 10!. This gives the answer:
26! / (6! 10! 210) = 150,738,274,937,250.
More abstractly: the number of ways of choosing m pairs out of n objects is:
n! /((n-2m)! m! 2m)
If you want to convince yourself of this formula you might like to check that there are:
- 3 different ways of putting 2 pairs of wire into 4 plugboard sockets.
- 15 different ways of putting 3 pairs of wire into 6 plugboard sockets.
From this formula we can find out something which often surprises people, which is that the number of possible plugboard pairings is greatest for 11 pairs, and then decreases:
1 pair: 325
2 pairs: 44.850
3 pairs: 3,453,450
4 pairs: 164,038,875
5 pairs: 5,019,589,575
6 pairs: 100,391,791,500
7 pairs: 1,305,093,289,500
8 pairs: 10,767.019,638,375
9 pairs: 58,835.098,191,875
10 pairs: 150,738,274,937,250
11 pairs: 205,552,193,096,250
12 pairs: 102,776,096,548,125
13 pairs: 7,905,853,580,625
The total number of combinations is thus (even for the simplest military Enigma) of the order of 15,000,000,000,000,000,000
Last updated on Saturday, 29th November 2003, 03:54:47 PM.
Prof. Ashay Dharwadker