# Many Applications And Information

Today, many applications and information are shared on internet and networks; the need to secure this information is crucial part in transmission. Encryption provides data confidentiality by changing the original format and content of a data into a scramble format that cannot be read, thus hiding the content of the data. Symmetric key encryption uses one key for the encryption and decryption. for an encryption to take place, a key and an algorithm is needed.

The algorithm are the steps used to thoroughly mix the plaintext with the key to produce encrypted data called ciphertext. This paper describes some algorithms used for symmetric key encryption.Information security has become a necessary aspect of life as Everyday millions of internet-dependent applications are used. Applications for financial, medical, military, educational purpose are highly sensitive and require some form of protection before being transmitted on the internet.

Encryption provides data confidentiality by hiding the meaning and content of information transmitted over an insecure network from any unauthorized party. The process of Encryption transforms plaintext (ordinary or readable data) into ciphertext (unreadable format). The reverse transformation is called Decryption. If encryption is done properly only the intended recipient can decipher the message using an algorithm and key.

The security of encrypted data depends mostly on the key thought other criteria are involved in keeping the encryption system secure.[1, 2, 4, 5].Many encryption algorithms are widely available and used to secure information. They are categorized into two: the symmetric key encryption and the asymmetric key encryption. The symmetric key encryption uses one key for encryption and decryption. It is also called private or secret key encryption. For encryption/decryption to work, the sender and the recipient must have a copy of the key before transmission and the shared key must be kept secret at all times.

Symmetric encryption is simple and fast so it is used to encrypt bulk data. The main difficult associated with it is key distribution or key exchange [1, 30]. For secure transmission to take place in the first place, the keys have to be exchange in a secure manner. So sharing the keys to both parties especially if they are not in close proximity can be difficult.

DES, IDEA, RC5, CAST, GOST, AES, and many more are examples of Symmetric encryption.Asymmetric (also called Public) key encryption solves the problem of key distribution. For encryption/decryption transformation, asymmetric algorithm makes use of key pair (ie 2 keys): the public key and its corresponding private key. The public key is usually used for encryption while the private key is for decryption. A message encrypted with a particular public key can only be decrypted by its corresponding private key.

The private key is kept secure or hidden while the public key is openly distributed so there is no need for key exchange before encryption can take place. Asymmetric key encryption is based on complex mathematical functions which are computationally intensive. This makes it up to 1000 times slower than symmetric techniques because it requires more computer resources [30].

RSA, ECC etc are examples of public key encryption.The concept of encryption are used in internet applications like Ecommerce, online banking, social network, visa card number protection, military communications, passport protection etc.

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