Field of cryptology

Cryptography consists of the following 3 fields:

  1. Symmetric Algorithms

  2. Asymmetric Algorithms

  3. Cryptographic Protocols

  4. Symmetric Cryptography

[Keywords] (a) key: key space, symmetric key, secret key, single key (b) plaintext, cleartext: (c) ciphertext (d) encryption, decryption (e) substitution, (f) attack: Brute-Force, Letter Frequency Analysis

[key] : literally the key to encrypt/decrypt messages : transmitting and storing a key secretly => transmitting a message securely

[plaintext] : the original message : it is also called "cleartext"

[ciphertext] : the encrypted message

[substitution cipher] : substitute each alphabet with another alphabe according to the substitution table (the key here) : one of the simplest methods to encrypt messages : it is also called "replacement cipher" : NOT SECURE AT ALL: Brute-Force Attack, Letter Frequency Analysis

[Brute-Force Attack] : : if an attacker steals the ciphertext by eavesdropping on the channel,