Application And Principles For Encryption Computer Science Essay

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Nowadays where much of business, news, formal, informal and private information and financial transactions are processed and carried out over the Internet, data encryption is very important considering computer security. HTTP, e-mail, FTP, and Microsoft Windows file-sharing can be accessed easily by internet hacker or network sniffer (John Mallery, Jason Zann, Patrick Kelly, Wesley Noonan, Eric seagren, Paul Love, Rob Kraft, and Mark O'Neill, P. 258).

As Jan L. Harrington states "Encryption is the best technique for ensuring the privacy of a message". According to Barry Dorrans "ASP.NET introduced a framework such as Authentication and Authorization using data encryption to determines the identity of authorized user and prevents unauthorized user to access the content". Data encryption defines a mathematical calculations and algorithmic schemes which convert plaintext into cyphertext which is non-readable to unauthorized parties.

Application for encryption

Nowadays in all electronic communication there are a number of participants involved such as sender, receiver, carriers' service provider etc. Data Encryption prevents hackers from listening in on private communications. Even if anyone success to capture the message, they can only see scrambled text because of encryption (SpamLaws. No date).

Encryption provides Secure Sockets Layer (SSL) which enables secure communications and user authentication over open and unsecured Internet such as financial transaction. Nowadays an international wireless security standard called Wi-Fi

Protected Access (WPA2) is being used to encrypt data transfer over wireless networks.

Digital television provides manage their subscriber access by encrypting video and audio signals (Parliamentary Office of Science and Technology, 2006). Encryption is also very essential for national security of any country. Military communications use data encryption so that terrorists and anti social elements cannot tapped message.

Principles of Encryption

Encryption always requires a key which determines the output of the algorithm. This key is usually piece of information, used as a parameter in encryption algorithm. Encryption schemes come in two categories: symmetric and asymmetric (Barry Dorrans, P.124).

Symmetric Encryption also known as single-key encryption is a type of encryption where a secret key is being shared to encrypt and decrypt information. A secret key can be a word, a character, or just a string of random letters. The sender and receiver both should know the secret key in order to retrieve or send information. Popular symmetric-key encryption algorithms are Blowfish, RC2, RC4, AES, and IDEA etc. Most of these operations are based on replacement and scrambling which means some bytes is replaced with other bytes according to algorithm rules (Encryption and Decryption, no date). The .NET framework provides various symmetric algorithms that share a common characteristic - they are all block ciphers which encrypts data by breaking it down into blocks (commonly 64 bits).

As Barry Dorrans states "Asymmetric Encryption was developed to eliminate the sharing of key between sender and receiver. Asymmetric Encryption use two keys - one for encrypting (known as the public key) and one for decrypting (known as the private key)". In .NET framework, there is a 'RSACryptoServiceProvider' class which supports this type of encryption. The key size of this class is 1024 bits. When a user wants to forward a file, they just encrypt the information adding recipient's public key. Once the recipient receives the file they retrieve the information by using the private key (Larryjf, 2004). Asymmetric Encryption works with digital signatures which allows recipient to validate the incoming data source.

Comparison between

Symmetric encryption and Asymmetric encryption

Symmetric encryption is very efficient algorithm in hardware and software implementation where Asymmetric encryption is on the order of 100-1000 times slower than symmetric encryption.

The shared key must be exchanged securely between each pair of communicating entities in symmetric encryption. Knowledge of the public key of an entity is sufficient to communicate securely in asymmetric encryption.

In asymmetric encryption each entity needs to protect the secrecy of its own private key where the secrecy of the key must be protected in symmetric encryption as each key is being shared at both entities (Christos Douligeris, Dimitrios N. Serpanos, and 2007 P.472).


Symmetric encryption and Asymmetric encryption

To maximize the advantage of both types of encryption scheme is to create a random symmetric key which will encrypt the data. Then it will encrypt the key asymmetrically. After that it can be added to the encrypted message. After the receiver receives the key, decrypts it using the private key, and then uses it to decrypt the message. This type of encryption is known as hybrid encryption. There are many protocols that uses hybrid manner by combining asymmetric and symmetric algorithms. Such as IPSec which provides integrity, privacy services for data diagram and web authentication (Peter Thorsteinson, G. Gnana Arun Ganesh, P.107).


Due to internet's open nature and the risk of web surfing, applying data encryption to the communication medium such as instant messaging and emailing is becoming very popular nowadays. Without this encryption mechanism, anyone can easily capture and view the information, being transferred over the internet. Especially data encryption is well worth pursuing when considering crimes like identity theft are on the rise.