Chapter 08 - Linux Networking and Security Chapter 8 Making...

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Linux Networking and Security Chapter 8 Making Data Secure
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Making Data Secure Explain commonly used cryptographic systems Understand digital certificates and certificate authorities Use the PGP and GPG data-encryption utilities Describe different ways in which cryptography is applied to make computer systems more secure
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Cryptography and Computer Security Computer security is about making certain that the only people accessing resources or data are those whom should have access Cryptography is the science of encoding data so that it cannot be read without special knowledge or tools; it is a key part of network applications and normally hidden from view Network connections can be tapped to allow for viewing of transmitted data - called sniffing the network, and encryption can block this
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Cryptography and Computer Security
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Basic Encoding Techniques The process of cryptography is as follows: Begin with the message to transmit - called the plaintext Apply a technique or rule called a cipher to change the plaintext The result is ciphertext, an encrypted message The most elementary example of encryption is letter- substitution where a different letter of the alphabet is substituted for each letter in the message
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Key Systems Rules, known as algorithms, allow letter-substitution to convert plaintext to ciphertext The level of complexity of an algorithm can be increased by using a key, a code necessary to encrypt or decrypt a message correctly using the algorithm Knowing the algorithm (the cipher) should not enable readability; good security assumes an eavesdropper knows the cipher, but the key must be kept secret
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DES The Data Encryption Standard (DES) was developed in the 1970s and uses a 56-bit key to encrypt data using various algorithms 56 bits provide for 2 56 possible keys It now takes 20 hours to break a DES key DES is being phased out, but it is still widely used since relatively few people have the equipment to break the key, 20 hours is still a relatively long time in the Internet age, and it was a widely implemented U.S. standard
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Chapter 08 - Linux Networking and Security Chapter 8 Making...

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