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. These algorithms are usually used to provide a digital fingerprint of data and act as proof that the data has not been altered by unauthorized entities including viruses. Often, these algorithms that primarily prove the integrity of the information encrypt passwords. (Kessler, Gary C., 1998)
It should be noted that the above schema have been treated rudimentarily. There are numerous examples of each type of algorithm that are being used regularly in the information technology world but these too have been kept beyond the purview of this paper.
Cryptography also serves some security requirements specific to application-to-application communications in the information technology world.
It serves to authenticate the users' identity. It should be noted in this context that the most widely used network in use today in the world - the Internet - has very weak host-to-host authentication in the forms of name or address based identity.
It serves to maintain privacy and confidentiality by ensuring that only intended users have access to the relevant information. Both the sender and the receiver are reassured of these.
It serves to non-repudiate - it authenticates that the sender really sent the message. (Kessler, Gary C., 1998)
Cryptography is such a vast science today that if this paper was to treat to any extent all the concepts inherent within it this paper would take the semblance of a mere glossary of terms. Thus, to avoid such low