COMPUTER FUNDAMENTALS

Detailed explanation-1: -In substitution cipher we replace each letter of the plaintext with another letter, symbol, or number; for the decryption, the reverse substitution has to be performed.

Detailed explanation-2: -A simple substitution is one in which each letter of the plaintext is always replaced by the same ciphertext symbol. In other words, there is a 1-1 relationship between the letters of the plaintext and the ciphertext alphabets.

Detailed explanation-3: -In cryptography, a substitution cipher is a method of encrypting in which units of plaintext are replaced with the ciphertext, in a defined manner, with the help of a key; the “units” may be single letters (the most common), pairs of letters, triplets of letters, mixtures of the above, and so forth.

Detailed explanation-4: -A substitution cipher takes each character (sometimes groups of characters) in a message and replaces it with a different character according to fixed rules. Every occurrence of one character will be substituted with the same replacement character.