How to Code a Substitution Cipher in C. Posted: June 16, 2025 | Last updated: June 16, 2025. Learn how to build a multivariate linear regression model step by step—no libraries, just pure C++ logic!

So, for example, if you read an entire paragraph and notice that the letter D appears more often than any other, odds are that it used a Caesar cipher with a shift of 1 (making E a D in the code).

Some ciphers have simple keys, others, complex ones. The key for a cipher used by Augustus Caesar, some 2,000 years ago, was simple enough: The receiver just had to shift the alphabet one position.

The intriguing world of cryptography has its roots in non-standard hieroglyphics, which were discovered on the walls of an Egyptian tomb in 1900 BC. In India, around 400 BC, “substitution cipher ...