In cryptography, a Caesar cipher, also known as Caesar’s cipher, the shift cipher, Caesar’s code or Caesar shift, is one of the simplest and most widely known encryption techniques.
It is a type of substitution cipher in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on. The method is named after Julius Caesar, who used it in his private correspondence.
This project is part of The Odin Project’s Ruby Programming curriculum.
• Function is called with two arguments – a string, and the desired ‘offset’
• The string is iterated over to check whether each character exists in an array of alphabet letters
• If the character is found, the offset value is added to the character’s index
• To ensure that the new index is within the index range of the array, the modulus is calculated using the modulo operator
with the length of the array. e.g. 28 % 26 = 2. This ensures that the index always ‘rotates’ around the 26 possible indexes.
• The character at the new index is added to an array of results
• If the character wasn’t found in the array, the original character is added to the results array
• The results array is returned.