Cryptography lecture/tutorial: Substitution techniques for transforming plain text to cipher text

In cryptography, there are two technique to convert plain text to cipher text for semester exams with notes 1 Substitution 2 transformation Substitution Cryptography technique methods 1 Caesar cipher cryptography substitution technique in this cryptography technique, the character of a plain text message is replaced by other characters like an alphabet three places down the line 2. Modified version of Caesar cipher substitution technique this is the more advanced version with the modification that letter of plain text can be changed to any number of the alphabet but after selecting the number it will remain constant 3. Monoalphabetic cipher cryptography technique In this substitution cryptography technique, now alphabet of plain text can be replaced by any other alphabet except itself 4. Homophonic substitution cipher cryptography technique this substitution cryptography technique is similar to monoalphabetic cipher except each word can be replaced by a set of alphabets 5. Polygram substitution cipher cryptography technique In this substitution technique group of words are replaced with another block of letters (no single letter is transferred group is transferred)