Encryption and Decryption algorithms are known.Three important characteristic of this problem enable us to use brute-force cryptoanalysis. In a similar way “A” is the plaintext then Ciphertext will be – “E”.įor each plaintext (P), Ciphertext (C) is. Suppose “M” is the plaintext and the key is given as 4, then you get the Ciphertext as the letter “Q”. The Caesar Cipher involves replacing each letter of the alphabet with the letter – standing places down or up according to the key given. Substitution Method is where letters of plaintext are replaced by other letters or by numbers or symbols or if plaintext is viewed as a sequence of bits, then substitution involves replacing plaintext bit patterns with Ciphertext bit patterns. We are discussing here, the Caesar Cipher that comes under the Substitution Method. Single-key or private / two-key or public ( Symmetric or Asymmetric) Substitution Method or Transposition Method You can characterize cryptographic systems by checking out the below points. We call it Cryptography – That actually makes the operation to transfer the plaintext into the Ciphertext. If you don’t have the same key, there is no other way you can get the plaintext. Here, it goes via a decryption algorithm which also needs the same shared key that is there on the sender side. to encrypt the plaintext – Ciphertext, the Ciphertext gets transmitted to the receiver. Now, when these three things (plaintext, encryption algorithm and the key) complete their individual work i.e.

Now, this key is actually shared between sender and receiver, and no other entity other than sender or receiver must get the key. It will first go to the Encryption algorithm where a secret key is also taking part with algorithm. Here, you can see that a plaintext is ready to be sent to the receiver. The below image will help you understand the Symmetric Cipher Model. At the receiver part, this Ciphertext gets decrypted by some decryption algorithm, so that the receiver can read the message. It has a plaintext that is to be encrypted in Ciphertext via some encryption algorithm, and sent via a secure channel to the receiver. We are taking here about the Symmetric Cipher Model which really is very easy to understand. The key part can be a public or private key depending upon which model you are working on – Symmetric or Asymmetric Model.

cryptology - field of both cryptography and cryptanalysisįor any secure communication, there is a need for three things - Encryption Algorithm, Decryption Algorithm, and a Key.

cryptanalysis - (code-breaking) study of principles/ methods of deciphering ciphertext without knowing key.

cryptography - study of encryption principles/methods.decipher - (decrypt) recovering ciphertext from plaintext.encipher - (encrypt) converting plaintext to ciphertext.key - info used in cipher known only to sender/receiver.cipher - algorithm for transforming plaintext to ciphertext.So, it is necessary to understand the basic terminology that we will be using in our article. To understand the mess of Information Security is beyond the scope of my article, but I can give you a partial understanding by taking a resourceful model of information security.

Polyalphabetic cipher decryption tool