In cryptographic terminology, a message is referred as clear text or plain text. The process of hiding the contents of a message from unauthorized persons is called as Encryption. The encrypted message is referred as cipher text and only authorized persons can read the encrypted message. Decryption is a process of retrieving the plain text from the cipher text. The cipher is a method of encryption and decryption. The encryption and decryption process will use a key. By using the proper key, the authorized person can decrypt a message. Nowadays, most of modern algorithms are using a key to secure the content of a message. Only few algorithms are not using a key.Generally, cryptographic algorithms can be classified into three types. We can decrypt a message only if the key used for decryption matches the key used for encryption.

1) Symmetric (or secret key) algorithm
2) Asymmetric (or public key) algorithm
– are two main classes of the key-based algorithms.

TOOLS REQUIRED:
ModelSim XE III 6.4b- is used for Simulation.
XiLinx ISE 10.1- is used for Synthesis.

LANGUAGE USED: VHDL