# 01 What is Rotation?

A rotation is a substitution of letters within an alphabet by shifting them a defined number of places. The shift is cyclic, i.e. when the boundary is crossed upwards, the shift continues at the beginning.

In geocaching the following rotations are common:

• ROT-13: Shifting of letters by 13 digits: ABC → NOP
• ROT-5: Shifting of digits by 5 digits: 012 → 567
• ROT-18: Combination of ROT-13 and ROT-5
• ROT-47: Shifts characters by 47 digits over all ASCII characters from 33 – 126: A → p, L → {, a → 2

GC Wizard allows rotation by arbitrary digits in addition to these standard rotations.

## Note – important – differentiation between rotation and Caesar

Rotation is not identical to Caesar – even if it looks like it at first glance!

We move ABC with ROT14 to OPQ. It is noticeable that if you treat the coded text with ROT14 again, it obviously does not become ABC, but rather CDE, correct?

So to get back to ABC, you have to go backwards, i.e. do ROT minus 14. However, ROT-14 is the same as ROT12 (since 26 minus 14 = 12 and the rotation in the alphabet is cyclical). It doesn’t matter whether I go 14 steps backwards or 12 steps forwards. The correct decoding of ROT14 is therefore ROT12.

It is clear that Caesar spits out the correct result: Caesar is a defined encryption type with its own key. And it is clearly defined for this algorithm that you get a key, in this case the key 14, and therefore go back 14 steps when decrypting.