Uses Of Encryption Algorithms Encrypted string generations Encrypting drives, files, passwords, credit card numbers, and message send of networks.

Whole Drive(Full Disk) Encryption Entire disk is encrypted. At next System boot up, you enter a decryption key and the entire drive is decrypted. While decrypted (and connected to an intranet/internet) the disk is vulnerable to being read.

Trusted Platform Module (TPM) Add-in chip added to some processor-motherboard. Generate Encryption keys and stores them on the hardware (not the disk drive) and the disk drive can only be decrypted by the hardware on your computer. This prevents someone steeling you hard-drive (or memory stick) and using it on another computer.

Filesystem Level Encryption Example: Windows Encrypting File System (EFS)

Secure files on a web server You have a folder www.facebook.com/secretStuff/ This folder is available to the general public You want to put a file in this folder that no one can read by the intended person www.facebook.com/secretStuff/jimStuff.pdf Anyone who guesses the file name jimStuff.pdf and know the folder secretStuff can go looking for it, and read it.

Encrypt the file…send public key We can encrypt the file with a private key, then put the public key in a session variable for a properly logged in user to view the file. This would require all files to be encrypted with the same private key for that user for that login session. There for dynamic encryption of files needs to be done. When a user requests a file, the file gets encrypted at that moment, appears in a web page as a link and the decryption key is given to the user in a session variable so only that user can see the file.

Files in Private and public folders Public folders content is available publicly Private folders content is not We can copy a file over to the public folder temporally Might be good to have a cryptic name www.facebook.com/publicStuff/eRF_98eGSVres!.pdf

Creating encrypted file names(php) $fileName = ‘somewhatPrivateFile.pdf’; $date = date(‘m’); // get current month $salt = “facebook file encryption salt”; $encryptedFileName = encrypt($fileName,$date,salt) copy(private/$fileName, public/ $encryptedFileName ); - Since we know the names of files we can simply regenerate all encrypted file names and delete them after a reasonable amount of time.

Encrypted data sent over internet HTTP – hypertext transport protocol HTTPS – secure HTTP Messages are sent from client (you) to the server (facebook) in encrypted format. Then entire message is sent over the network as encrypted data. So no one along the path can read the data.

Recording encrypted data in a database

Encrypted Credit Card Number Visa may provide Amazon with a public Key to encrypt credit card numbers with and store in Amazon’s database. When a purchase is made, Amazon sends the encrypted CC number to Visa who uses the Amazon private key to decrypt the credit card number and process the purchase. This prevents employees of Amazon or system hackers to expose <customer CC number> pairs. Amazon can maintain credit number even so repeat customers don’t have to repeatedly type in the credit card number.