tailieunhanh - Open Source Security Tools : Practical Guide to Security Applications part 32

Open Source Security Tools : Practical Guide to Security Applications part 32. Few frontline system administrators can afford to spend all day worrying about security. But in this age of widespread virus infections, worms, and digital attacks, no one can afford to neglect network defenses. Written with the harried IT manager in mind, Open Source Security Tools is a practical, hands-on introduction to open source security tools. | Page 289 Thursday June 24 2004 11 12 PM Types of Encryption 289 Caution If you implement PGP improperly it can provide little or no protection at all. You can also irrevocably lose your data if you are not careful with your decryption keys see the sidebar Don t Lose Your Keys . PGP is considered a hybrid cryptosystem which means that it uses a combination of symmetric and asymmetric encryption to accomplish its function. Public key encryption takes a lot more processing power than shared secret encryption because public key encryption typically uses complex math involving prime numbers. PGP uses only public key encryption to create a session key which is then used to encrypt the whole message using traditional symmetric cryptography. Most public key cryptosystems use this method to improve performance. Rather than type in your whole private key each time you use PGP which would take quite some time and be very prone to error your private key is stored on your hard drive in encrypted form. To unlock your key you type in a pass-phrase each time you use PGP. This is like a password only generally it is longer and made up of several words preferably with numbers and letters. This pass-phrase is very important to remember because if you ever lose or forget it you won t be able to recover the data you encrypted with PGP. Installing PGP and Generating Your Public Private Key Pair 1. First download the PGP program file from the Web site. 2. Click on this self-extracting zip file and it will automatically begin the installation process. 3. You have the option of purchasing a full license or evaluating the product. Click on Purchase Now if you want to get a full version authorized for commercial use. Otherwise click on Later to use the freeware version. 4. The install program then guides you through the process of generating your public private key pair. This process is very important as it is the heart of the protection that PGP provides. 5. The program .