CRYPTOGRAPHY :Cryptography in layman’s terms would mean the study of creating messages in a form of secret code that masks the actual message and displays it as something completely unintelligible.These cryptic messages make absolutely no sense to the casual observer, but the original content can be reconstructed by the intended recipient. That’s what cryptography is about—it uses complex mathematical calculations and computer science to pull off the job.

ENCRYPTION: Encryption is simply the implementation of cryptography. It is the process by which messages are converted into encrypted files. These files are password-protected by the creator author.Without the password, the file cannot be accessed and the original contents cannot be extracted. On entering the password correctly, the computer decrypts the file,revealing the actual message or data. Prior to encryption, data is simply referred to as ‘plaintext’ but once encrypted, it is called ‘ciphertext’, which means jumbled or puzzled data.

CIPHER: In simple terms, a cipher is a code or a set of instructions. More accurately put, it’s an algorithm that contains precise instructions for encrypting and decrypting data. In the world of encryption, there are two main types of ciphers; the transposition cipher and the substitution cipher. The two work in completely different ways. The former rearranges characters in a file, making them look illogical e.g. the word ‘COMPUTER’ might look like ‘UEORCPTM’ after encryption.The second method completely changes the content to corresponding values, and then reconstitutes it upon decryption, e.g. The word ‘COMPUTER’ might look like ‘YGBLWDJI’. In this example, the letters in both words correspond to each other sequentially starting from the first (A=W,B=X, C=Y, etc).

ALGORITHM: In the field of mathematics, an algorithm is a predefined set of precise instructions for a task to be accomplished successfully, from the initial stage right to the output. For instance, when you try switching on your computer and it doesn’t come on, you check the connections. If connections aren’t ok, you fix them and if they are, you look for a fault somewhere else, ruling out different possibilities at each step. It is an ‘if-then’ principle.

KEYSTREAM: A keystream is a collection or a stream of alphanumeric and special characters combined with the actual message. These characters are either randomly placed or appear to be random in nature.

BRUTE FORCE ATTACK: A brute force attack is an intensive trial-and-error procedure by which a person can try to crack the key or password of a file by trying different combinations of alphanumeric or special characters until the perfect match is found.

Many times other takes your data from your computer without your permission via USB drives.This is a security threat. If you want that no one can copy your data without your permission,You can do so by editing registry values. To prevent access of usb drives at lest you need windows xp service pack 2.To start registry editor you need to log in through a user account that have administrator rights.

1.Open the start menu and click on run

2.In the text box type 'regedit' and press Enter. Registry Editor will Open.

3. open 'HEKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\StorageDevicePolicies' Key

4.If it does not exist , create it with ' Edit|New | Key' and rename it 'StorageDevicePolicies' and select it.

5.Now create a registry value by Right clicking on right side of window and select 'New| DWORD' and rename it with ' WriteProtect'

6.Now right click on it and select 'Modify' and set the value 1

now close the registry editor and restart the computer.

Now ,Your data is protected. NO one can copy you data by USB DRIVES.

When you wants allow the pen drive, change the value 0 from 1 nd restart computer.

Pen-drives will allow to copy data.

Have a FUN!!!!!!!!!!!!!!

 

Windows XP has a special feater that allows the user to use computer after forgetting password. It creates a password reset disk to reactivate your user account and reset the forgotten password. CREATE A PASSWORD RESET DISK : To create password reset disk follow these steps 1.Open the CONTROL PANEL 2.Click on USER ACCOUNTS to open it. 3.When it open choose an account with Administrator rights and click on it. 4.Plug a removable media like as a] pen-drive etc. 5.Click at the 'Prevent a forgotten password' in the 'Related Tasks' box at the top-left corner of window. 6.A wizard will come.Click on the next. 7.Again click on Next. 8.Enter the current password and click on next. 9.After few seconds password reset disk is cerated.Click on Next and then click on Finish. Now your password reset disk is ready for use. USING THE DISK: Boot you computer.When it asked for password press ENTER.A massage will appear 'Click hare to use the password reset disk' . Now Click on it. A wizard will come . click on next and insert the disk.You will have define new password or repeat it blank and click on next and then Finish. Now you log on in your computer. Have a fun!!!!!!!!!!!!!!!!!!!!!!!!!