Cryptography is way you can keep information
secure. A person who does not know the
method used to change the information to
keep it secure cannot copy the method used or reverse the change. The basic
components of cryptographic systems are used to encipher (scramble) information
so that it is difficult to determine the meaning without the appropriate
key or key(s) to decipher (unscramble) the information. The components
include cryptographic algorithms (mathematical functions) for enciphering
or deciphering information and keys.
Symmetric and asymmetric are two examples
of cryptographic systems. Symmetric systems use the same key to encipher
and decipher. Asymmetric systems
generate and use different keys to encipher
and decipher a secure key pair. With this key pair, consisting of a public
key and a private key, only one key can decipher what the other enciphers.
Merely knowing one key does not make it
very likely that someone will be able to figure out the other key. Asymmetric
key pairs are used in creating digital signatures and transporting symmetric
In the past, most encryption systems only
used symmetric cryptography. The problem with symmetric cryptography though,
is the difficulty encountered in distributing keys to certain people. Since
symmetric cryptography uses the same key for enciphering and deciphering,
a person has to use creative and difficult means to prevent someone from
intercepting the key. If a third party were to intercept the key, they
could use it to decipher anything it was used to encipher.
A solution to this problem is public key
cryptography which uses asymmetric cryptography to transport symmetric
keys. In such a system, a recipient's public key is used to encipher a
symmetric key. Once enciphered, the symmetric key can only be easily deciphered
using the corresponding private key.
Keys can be of varying length, typically
from 128-bits to over 2000-bits. Obviously, the larger the key, the more
secure the information you’re encrypting.