Ciphertext

Understanding Ciphertext

Ciphertext is the result of applying a cipher algorithm to plaintext in the realm of cryptography. This encryption process transforms readable text into an unreadable form.

Ciphertext contains both encrypted and encoded information. It retains the original plaintext but is incomprehensible to unauthorized individuals or computers without the proper cipher to decrypt it.

Decryption is the reverse process of converting ciphertext back into readable plaintext.

A cipher is an algorithm that converts plaintext into ciphertext. It produces an unreadable output through encryption.

It is important to note that manual cipher algorithms used in the past differ from modern algorithms executed by machines.

One type of cipher is the substitution cipher, which offers an alternative to plaintext. Another type is the polyalphabetic substitution cipher, where the plaintext is encrypted using a mixed alphabet that randomly changes to a different mixed alphabet, indicated by an uppercase letter.

The transposition cipher, also known as the rail fence cipher, is another type of cipher that rearranges the plaintext through permutation.

There is also the permutation cipher, where the positions of the plaintext are shifted according to a regular system, resulting in a ciphertext that is a permutation of the original plaintext.

In private-key cryptography, both the sender and the receiver possess a pre-shared secret key, which is kept confidential. The attacker is aware of both the plaintext and the corresponding ciphertext. This type of encryption utilizes algorithms such as DES and AES.

In public-key cryptography, two distinct keys, namely the private key and the public key, are used for the encryption and decryption processes. The sender employs the public key for encryption, while the receiver does not possess the private key.