> For the complete documentation index, see [llms.txt](https://wiki.zacheller.dev/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.zacheller.dev/network-security/courses/isci-cnss-course/fundamentals-of-encryption/the-history-of-encryption.md).

# The History of Encryption

### The Caesar Cipher

A substitution cipher. Either you can shift to the right or to left by any number of spaces you like.

### ROT 13

Single alphabet substitution cipher.

### Multi-Alphabet Substitution

In this scheme, you select multiple numbers by which to shift letters (that is, multiple substitution alphabets).

### Rail Fence

A type of transposition cipher.

```
A      tc      a      dw

      ta      k      ta      n
```

Becomes: **atcadwtaktan**

### **Vigenère**

Vigenère is a polyalphabetic cipher and uses multiple substitutions in order to disrupt letter and word frequency.

### **Enigma**

The Enigma is a sort of mechanical polyalphabetic cipher. The operator of the Enigma machine would be given a message in plaintext and then type that message into Enigma. For each letter that was typed in, Enigma would provide a different ciphertext based on a different substitution alphabet. The recipient would type in the ciphertext, getting out the plaintext, provided both Enigma machines had the same rotor settings.