23-06-2012, 12:29 PM
CRYPTOGRAPHY
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Everyone has secrets; some have more than others. When it becomes necessary to transmit those secrets from one point to another, it's important to protect the information while it's in transit. Cryptography presents various methods for taking legible, readable data, and transforming it into unreadable data for the purpose of secure transmission, and then using a key to transform it back into readable data when it reaches its destination.
Basic Idea
The goal of cryptography is to make it possible that two people to exchange a message in such a way that other people cannot understand.
There is no end that number of ways this can be done, but here we will be concerned with the methods of altering the text in such a way that the recipient can undo the alteration and discover the original text.
INTRODUCTION TO CRYPTOGRAPHY
Predating computers by thousands of years, cryptography has its roots in basic transposition ciphers, which assigns each letter of the alphabet a particular value. A simple example is to assign each letter a progressively higher number, where A=1, B=2, and so forth. Using this formula for example, the word "wiseGEEK", once encrypted, would read "23 9 19 5 7 5 5 11".
Encryption and decryption
The method of disguising plaintext in such a way as to hide its
substance is called encryption. Encrypting plaintext results in unreadable gibberish called cipher text.
SECURE SOCKET LAYER
The Secure Sockets Layer (SSL) is a common encryption protocol used in e-commerce. When you make a purchase over the Internet, this is the technology the merchant uses to make sure you can safely transmit your credit card information.
Using this protocol, your computer and the online merchant's computer agree to create a type of private "tunnel" through the public Internet. This process is called the "handshake." When you see a URL in your Web browser that starts with "https" instead of "http", it is a secure connection that is using SSL.
SECRET KEY
Some methods of cryptography used a "secret key" to allow the recipient to decrypt the message. The most common secret key cryptosystem is the Data Encryption Standard (DES), or the more secure Triple-DES which encrypts the data three times.
[attachment=25214]
Everyone has secrets; some have more than others. When it becomes necessary to transmit those secrets from one point to another, it's important to protect the information while it's in transit. Cryptography presents various methods for taking legible, readable data, and transforming it into unreadable data for the purpose of secure transmission, and then using a key to transform it back into readable data when it reaches its destination.
Basic Idea
The goal of cryptography is to make it possible that two people to exchange a message in such a way that other people cannot understand.
There is no end that number of ways this can be done, but here we will be concerned with the methods of altering the text in such a way that the recipient can undo the alteration and discover the original text.
INTRODUCTION TO CRYPTOGRAPHY
Predating computers by thousands of years, cryptography has its roots in basic transposition ciphers, which assigns each letter of the alphabet a particular value. A simple example is to assign each letter a progressively higher number, where A=1, B=2, and so forth. Using this formula for example, the word "wiseGEEK", once encrypted, would read "23 9 19 5 7 5 5 11".
Encryption and decryption
The method of disguising plaintext in such a way as to hide its
substance is called encryption. Encrypting plaintext results in unreadable gibberish called cipher text.
SECURE SOCKET LAYER
The Secure Sockets Layer (SSL) is a common encryption protocol used in e-commerce. When you make a purchase over the Internet, this is the technology the merchant uses to make sure you can safely transmit your credit card information.
Using this protocol, your computer and the online merchant's computer agree to create a type of private "tunnel" through the public Internet. This process is called the "handshake." When you see a URL in your Web browser that starts with "https" instead of "http", it is a secure connection that is using SSL.
SECRET KEY
Some methods of cryptography used a "secret key" to allow the recipient to decrypt the message. The most common secret key cryptosystem is the Data Encryption Standard (DES), or the more secure Triple-DES which encrypts the data three times.