Security is the concept of keeping information secret by protecting it from unauthorized users. In order to keep a data secured it must be hidden from unauthorized access (confidentiality), prevented from modifications (integrity) and available to authorized persons when needed (availability). Confidentiality, integrity and availability are thus, the three security goals (Forouzan, 2007, ). Security goals can be implemented using several techniques among which cryptography is the most general and widely prevalent one. Cryptography is a term of Greek origin meaning secret writing. In earlier days, cryptography referred only to the process of encryption and decryption, but today cryptography involves more complex processes and procedures. Any cryptographic system is usually characterized by three main dimensions, viz., the operations involved in the transformation of plain text to cipher text, the number of secret keys used and the method of processing the plain text (Stallings, 2011). Based on this, there are two broad classifications of cryptosystems. One is the symmetric-key cryptosystem (or shared-key cryptosystem) and the other is the asymmetric-key cryptosystem (or public-key cryptosystem). In symmetric key cryptosystem, encryption and decryption are done using the same key whereas in a public-key cryptosystem, encryption and decryption are done using two different keys. Among the two keys, one key is private and the other is public. Generally encryption is done using public key and decryption is done using private key but some schemes do the vice versa. In public-key cryptosystems, finding the private key from the public key is computationally infeasible. A public-key cryptosystem has six components e 1) Plain text; 2) Encryption algorithm; 3) Public Key; 4) Private Key; 5) Decryption algorithm; 6) Cipher text. The entire cryptosystem evolves around these key components. Public-key cryptosystems can be used for encryption/decryption, to create digital signatures and for key exchange. Among the public-key cryptosystems, the most popular one is the RSA cryptosystem developed by Rivest et al. (1978) at MIT. The RSA algorithm can be described as follows.