Rot 13 Encryption
Encryption is an ancient practice of trying to conceal information by scrambling it. Modern encryption techniques are incredibly strong and mathematically sound. But in the past, simpler and more primitive methods were used.
Let's implement a form of encryption known as a Caesar Cipher,
sometimes also known as Rot-13 encryption.
(Rot for rotation, and 13 for one amount that you might rotate.)
Here is how it works. Given a String
and an amount to rotate, we replace each character in the String
with
a new character determined by rotating the original character in a given array.
For example, given the String
array "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz ",
"ABC" rotated 3 would be "DEF", and rotated -1 would be " AB". (Note the space at the end of the character array.)
Declare and implement a function called encrypt
that, given a String
and an Int
amount, returns the passed
String
"encrypted" by rotating it the given amount. ("Encrypted" is in scare quotes because this is not by any
means a strong method of encryption!) If the passed String
is null
you should return null
.
Note that rotation may be negative, which will require some additional care.