In the present context, with the advent of computers in every aspect of daily routines of individuals and organizations in the 21st century, large amounts of information have to stored in or transmitted through unsafe media. It becomes essential that such information is not accessible to those who are not privy to it. Thus, to this effect of lending exclusivity to information stored or transmitted, the science of cryptography today has pervaded all areas of information technology today.
Towards these ends three types of cryptographic schemes are generally used today. The algorithms utilized in these schemes are described by the number of keys used to encrypt and decrypt data and additionally by their applications.
Public Key Cryptography (PKC) - These are asymmetric algorithms that use two keys - one key to encrypt and another to decrypt. One key is called the public key which may be advertised to all and sundry while the other is called the private key and this is only available to privy entities. It does not matter which key is used to encrypt or decrypt but the end-effect is the encryption allows the information to remain exclusive.
Hash Function (One-Way Cryptography) - These algorithms have no key and they allow the plaintext to be encrypted once into ciphertext that is not recoverable. ...