Science of changing plain text into cipher text by substituting or transposing characters
        Uses algorithms (mathematical formulas) and keys to create cipher text
          Earliest cryptography relied on human effort to create, break codes; today computers are used
Earliest Methods of Cryptography
          Substitution ciphers
          Maps each letter to another letter
          Prone to frequency analysis
          Vigenere cipher
        Polyalphabetic substitution
          Substitutes cipher letters according to keyword
          Assigns number values to letters (a=0)
          Adds value of each letter in keyword to letter values in plain text in order
        If you know length of key, can break cipher text into multiple simple substitution ciphers

Encryption with Vigenere Cipher
Breaking Vigenere Cipher Text Into
Simple Substitution Ciphers

Earliest Methods of Cryptography
          One-time pad
        Pad of paper with random selection of numbers (two copies)
        To encrypt, first letter of plain text shifted by first number on pad, second letter by second pad number, etc.
          Historic ciphers
        Enigma: WWII German machine creating complex substitutions
        Purple: WWII Japanese machine modeled after Enigma
Cryptographic Primitives
          Primitives: Four main areas of cryptography
        Random number generation
        Symmetric encryption
        Asymmetric encryption
        Hash functions
          Goals of cryptography: Confidentiality, integrity, authentication (CIA)
Random Number Generation
          Computer-generated random numbers are pseudorandom
        Computers cannot create fully random numbers
          Goal is unpredictability
          Depth concern: Algorithms cycle, repeat
          Two cryptographically secure pseudorandom number generators
        Blum-Blum-Shub pseudorandom number generator
RSA pseudorandom number generator

Symmetric Encryption
          Single-key encryption
        Same key used to encrypt, decrypt
          Used for confidentiality
          May provide integrity depending on mode used
          Analogy is lockbox
        Single key required
        Key is set of random bits
          Encryption strength depends on algorithm or cipher used
        Computationally secure: Time needed to compute all combinations is so large, can’t be done in reasonable amount of time

Stream Ciphers
          Type of symmetric encryption
          Stream of data: Each byte processed with preceding bytes; order is important
          Stream Cipher
        Uses single key to encrypt message or stream of data, e.g. one-time pad
        Does not require padding
        Provides integrity: If first bytes changed, errors propagated through message
Stream Cipher

Block Ciphers
          Type of symmetric encryption
          Blocks of message processed independently
          Must safeguard against:
        Identification of repeated blocks
        Changing of block order

Sharing Keys
          Keys: Must be known by both parties before algorithm can be used
          Sharing options
        “Pre-shared secret”
        Trusted third party
        Key agreement protocol
          E.g. Diffie-Hellman key exchange
          Prone to man-in-middle attack
Man-in-the-Middle Attack

 Asymmetric Encryption
          Requires use of two keys
        Private key known only by owner
        Public key available to users
          Public key used to encrypt data that only recipient with private key can read
          Because asymmetric encryption very slow, often used just to encrypt symmetric encryption key
          Digital signature:  Encrypts small attachment to message with private key to verify ownership
Digital Signature of Hash

Hash Functions
          Take messages and compute smaller, fixed-size message (digest, or hash)
          Provide better performance
          Provide integrity: Message always hashes to same digest
          Used in authentication blocks
          Used to create pseudorandom data
          Useful for storing passwords: However, passwords should be salted with pseudorandom values
          Keyed hash functions are designed to require keys


Internet Options Dialog Box

sampai sini ja sempat explore ! 
Penah jugak jumpa benda neh ? kalau yang guna server yang ada security msti ada. try cari .
HAHA . crytography neh sangat best ! 
sebarang penambahan buleh ja .silakannnn ..


Neh yang mana dilla taw ja .
selalu buad dekat windows XP .
tapi neh saja saja try kat windows 7 !
Menjadi (:
tapi pastikan la komputer tuu tada virus dulu ya!
sebab ! Kalau re-image .dia akan copy *sebijik sebijik yang asal .
ik0d jugak model laptop atau pc .

jum ! mula (:

Klik Start ---> all program

Accessories---> Maintenance----> Backup and Restore

Klik Back up computer

Okeys. dah habeh tuu .kita create a system image pulak !

Pilh la kat mana kita nak simpan !

hahhaha ! DAH SIAP kot ! try laaaaaaaaaaaaaaaaa (:
nak taw yang lagi banyak . tanya MR.gooooooogle okeys !


salam semua ! jum share (:
Format of recovery !
What is format?
Prepare a storage medium, usually a disk, for reading and writing. When you format a disk, the operating system erases all bookkeeping information on the disk, tests the disk to make sure all sectors are reliable, marks bad sectors (that is, those that are scratched), and creates internal address tables that it later uses to locate information. You must format a disk before you can use it.
Note that reformatting a disk does not erase the data on the disk, only the data on the address tables. Do not be panic, however, if you accidentally reformat a disk that has useful data. A computer specialist should be able to recover most, if not all of the information on the disk. You can also buy programs that enable you to recover a disk yourself.
The previous discussion, however, applies only to high-level formats, the type of formats that most users execute. In addition, hard disks have a low-level format, which sets certain properties of the disk such as the interleave factor.
Almost all hard disks that you purchase have already had a low-level format. It is not necessary, therefore, to perform a low-level format yourself unless you want to change the interleave factor or make the disk accessible by a different type of disk controller. Performing a low-level format erases all data on the disk.
The Format commands are typically run to prepare a new logical drives for use after disked hard drive - enabling the installation of an operating system, application programs & eventual user data. The format command has been around for a long time, formerly they were stand alone DOS programs before being integrated into Windows.

Where previously the computer would boot and be usable, systems that have been Formatted often report the following errors: (these errors are frequently displayed on a black screen with white text.)
·         Operating System not found
·         Invalid or corrupt FAT
·         Cannot find file or program
·         Invalid
·         Primary/Secondary Hard disk failure
·         Non system disk
·         Disk error
Or when a partition has been formatted, the all data would disappear.
To unformat files from formatted drives, please follow this procedure:
1.Download Ease US Data Recovery Wizard, install it and launch it. Click the Complate recovery button on the main window of Data Recovery Wizard. (If you cannot boot the computer, please use data recovery bootable disk or connect the hard drive to another computer as slave to recover lost data.)
Note: If the hard disk has mistakenly deleted volumes, hidden volumes, drives with failed operation/file system, you should use "Partition Recovery "

2. Select the file types you want to recover. Tick 'Search all lost files automatically' to find all lost file types. Tick 'Ignore bad sectors' to skip bad sectors when scanning.

3. The second screen on the "Complete Recovery" tool will display a list of volumes found on the drives found in your system. If the volume does not have a drive letter, then the volume will be listed at the hindmost and the drive letter will be instead by "*".
4. You should choose the volume that was formatted and click "NEXT" to start searching on this volume.

5. The Intelligent Searching module will scan on the selected volume, collect and analyse every byte on the volume, then show you a list of volumes which are possible on it.
6. After this scanning is finished, Data Recovery Wizard will permit you choosing 4 volumes at best to recover the data. And then, press "NEXT" button. The Data Recovery Wizard will launch the "Building directory" procedure to searching the files. You will see file/folder tree very soon.
7. Select the file or directory that you want to recover and press the "Next" button.
8. Select a directory and press the "NEXT" button to save the data .

  • YEAHHH !