Encryption for Data Security in Networks

One of the things that are important in communication using a computer to ensure the confidentiality of the data is encrypted. Encryption dalah a process to change a code of which can be understood to be a code that can not be understood (not legible). Encryption can be interpreted as a code or cipher. A coding system using a table or a dictionary that has been defined to replace the words of the information or that are part of the information sent. A cipher uses an algorithm that can encode all data streams (stream) bit of a message into an incomprehensible cryptogram (unitelligible). Because cipher technique is a system that has been prepared for the automation, then the technique used in computer and network security systems.In the next section we will discuss a variety of encryption techniques commonly used in security systems of computer systems and networks.

A. Conventional encryption.
 This encryption process can be described as follows: 

Plain text -> Encryption Algorithm -> Cipher text -> Algorithm Dekrispsi -> Plain text   

User A |                                      | User B

User B|---------------------- Lock (Key) --------------------| 

Figure 1 

Origin information that can be understood in symbolized by the Plain text, which then by the encryption algorithm translated into information that can not be to understand that symbolized the cipher text. The process of encryption consists of two algorithms and keys. Locks are usually a short string of bits that control the algorithm. Encryption algorithm will produce different results depending on which key is used. Changing the encryption key will change the output of encryption algorithms.Once the cipher text has been generated, then transmitted. In the next recipient of the cipher text received converted back to plain text and key algorithm and the same.Security of conventional encryption depends on several factors. First encryption algorithm must be sufficiently strong so that makes it very difficult to decrypt the cipher text with the basic cipher text. Furthermore the security of conventional encryption algorithms rely on the secrecy of the key is not the algorithm. That is assuming that it is very impractical to decrypt the cipher text based information and knowledge about the algorithm description / encryption. Or in other words, we do not need to maintain the secrecy of the algorithm, but enough with the secrecy of the key. 

Benefits of a conventional encryption algorithm is the ease in use widely. With the fact that this algorithm does not need to be kept secret with the intent that the makers can and are able to make an implementation in the form of chips with low price. Chips can be widely available and provided also for several types of products. With the use of conventional encryption, security principle is to maintain the security of the key. 

The model is widely used encryption is a model based on data encrytion standard (DES), taken by the Bureau of U.S. national standard in 1977. For the DES encryption of data on the 64 bit block using 56-bit key. By using this key, the 64 input data converted to a sequence of methods to 64-bit output. That the same process with the same key is used to change the encryption back.

B. Public-Key Encryption 
One of the main difficulties of the conventional encryption is the need to distribute the keys used in a safe condition. An appropriate way has been found to overcome this weakness with a model of encryption that is surprisingly not require a key to be distributed. This method is known as public-key encryption and was first introduced in 1976. 
Plain text -> Encryption Algorithm -> Cipher text -> Algorithm Dekrispsi -> Plain text                                       User A |                                           | User B

                                         Private Key B----|                                                                                         

|---------------------- Lock (Key) --------------------|

 Figure 2 

The algorithm is as depicted in the image above. For conventional encryption, the key used in encryption and decryption cent is the same. But this is not actually the required conditions. But it is possible to construct an algorithm that uses one key for encryption and her partner, a different key, for decryption. Furthermore it is possible to create an algorithm in which knowledge of the encryption key encryption algorithm plus not enough to determine the key dekrispi. So the following technique will be done:1. Each - each of the systems in the network will create a pair of keys used for encryption and decryption of information received.2. Each - each of the system will publish the encryption key (public key) to install in public registers or files, while her partner still maintained as a private key (private key).3. If A wants mengisim message to B, then A will encrypt the message with the public key of B.4. When B receives a message from A then B will use the private key to describe the message from A.As we have seen, public-key distribution because it does not solve the problem needed a key to be distributed. All participants have access to a public key (public key) and private keys generated locally by each participant, so no need to be distributed. During each control system - each private key with both the communication becomes secure communications. Each partner's private key system to change the public key will replace the old public key. The weakness of public key encryption method is compared with conventional encryption methods encryption algorithm has a more complex algorithm. So for comparison of size and price of the hardware, the public key method will result in lower performance. The following table will show the various important aspects of the conventional encryption and public key.

Conventional Encryption
Required to work:
1. The same algorithm with the same key can be used for the decryption process - the encryption.
2. The sender and receiver must share the same algorithm and key.
    What is needed for security:
1. Keys must be kept secret.
2. It is impossible or highly impractical to translate that information is encrypted.
3.Knowledge of algorithms and sample of an encrypted word is not sufficient to determient the key

 
Public Key Encryption
Required to work:
1. The algorithm used for encryption and decryption with a pair of keys, one for encryption one for                 decryption.
2. The sender and receiver must have a suitable key pair.
    What is needed for security:
1. One of the key must be kept secret.
2. It is impossible or highly impractical to translate that information is encrypted.
3. Knowledge of algorithms and sample of an encrypted word untu insufficient to determine the key.