What is... Cryptography?|
A Basic Introduction
Page 1: Introduction
by: John Holstein
The Study of Encryption: Cryptography
Symmetric and Asymmetric? Huh? Well, there are two basic classes of cryptography,
symmetric and asymmetric. These two classes are categorized by their use of
the "keying" material, or the code that is compared to text in order to "encrypt"
or "decrypt" the information. Symmetric crypto use the same (secret) key to encode
and decode a message or file, asymmetric crypto use's one (public) key to encode
a message/file and a different (private) key to decode it. Assymetric crypto is
otherwise known as public key crypto.
You can see from the above example that Symmetric Crypto has a little problem. How
do you get the single secret key to the location where the data will be decoded? You
would need to either 1) physically take the key to the site (a logistical nightmare
when dealing with big business and government) or 2) encrypt the new secret key with another key the target site already has, in this case, why encrypt the message with
a new key at all? Why not use the one they have?...see what I am getting at?
With Asymmetric, you do not have this problem, hence the popularity of PGP Crypto
Software. Asymmetric allows the use of a "Public" Key, which in the name, implies that
the public has access to this key. Anyone can encrypt data using this key, but only
the private key held by the target can decrypt it. A much more suitable situation for communication securely over great distances where the transfer of single keys becomes a problem.
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Comments? Questions? Bugs? John Holstein
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