What is Cryptography?

Cryptography is the art of encoding information by using specific techniques with the aim of such information can only be known and read by the right side. Cryptography is not merely technical, but also an art. This is because an attempt to break the password is also directly proportional to the effort encrypting, or even more. In its development so that any attacker (person who wants to break the cryptographic code) which called "cryptanalysis" and the cryptographers (principals cryptography) is always locked on each others creativity to each technique.

But the science of cryptography can not be separated from the engineering sciences. Particularly modern cryptography which relies heavily on mathematics. In contrast to the more classical cryptography technique modification of existing data in order not to be recognized. In this book we will be much talk about discrete mathematics which became a mainstay of "ElGamal" cryptography.

Actually there is science in addition to other cryptography to encrypt data that is stenography, which is a data encryption technique with increasing data - other data or abbreviate the data with a specific pattern. Examples of the shorthand is Digital watermarking. Explanation of stenography will be discussed in the chapter on stenography.

Cryptography itself divided by the time period Type 2, namely:

1. Classical cryptography.
2. Modern cryptography.

Meanwhile, if divided by type of cryptographic keys are used, then the cryptography is also divided by 2 is:

1) Symmetric Cryptography
2) asymmetric Cryptography

Cryptography is also divided based on 2 sharing data will be processed, namely:

1. Cryptography Chipper Block
2. Cryptography Stream