Plaintext is
an original text / data which will be converted into a random nonsense text
called ciphertext in order to prevent the original message being read
by the people out of the recipient. The encryption process consists of an algorithm that produce a
different output depending on the specific key being used at the time and a key which value is
independent of the plaintext and shared by sender and recipient. The ciphertext
can be transformed back to the original plaintext by using a decryption
algorithm and the same key that was used for encryption. The security of
conventional encryption depends on the secrecy of the key, not the secrecy of
the algorithm. It is impractical to decrypt a message based on the ciphertext plus
knowledge of the encryption/decryption algorithm. The principal security
problem is maintaining the secrecy of the key.
Security
of conventional encryption depends on several factors:
-. The
encryption algorithm must be impractical to decrypt a message on the basis of
the ciphertext and knowledge of the encryption/decryption algorithm.
-. Secrecy
of the key
Referring
to the image above, message (X) will be encrypted using algorithm key (K) and the
encryption process will produce the ciphertext (Y).
Y = EK(X)
While
the recipient will decrypt the
ciphertext (Y) into message (X) using the same algorithm key (K) as the key
used to encrypt.
X = D K(Y)
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