Remove Vigenere additions and document Playfair codec

Author: Copilot

README.md

@@ -285,12 +285,12 @@ This category also contains `ascii85`, `adobe`, `[x]btoa`, `zeromq` with the `ba
 - [X] `bacon`: aka Baconian Cipher
 - [X] `barbie-N`: aka Barbie Typewriter (*N* belongs to [1, 4])
 - [X] `citrix`: aka Citrix CTX1 password encoding
+- [X] `playfair`: aka Playfair Cipher
 - [X] `polybius`: aka Polybius Square Cipher
 - [X] `railfence`: aka Rail Fence Cipher
 - [X] `rotN`: aka Caesar cipher (*N* belongs to [1,25])
 - [X] `scytaleN`: encrypts using the number of letters on the rod (*N* belongs to [1,[)
 - [X] `shiftN`: shift ordinals (*N* belongs to [1,255])
-- [X] `vigenere`: aka Vigenere Cipher
 - [X] `xorN`: XOR with a single byte (*N* belongs to [1,255])
 
 > :warning: Crypto functions are of course definitely **NOT** encoding functions ; they are implemented for leveraging the `.encode(...)` API from `codecs`.

docs/pages/enc/crypto.md

@@ -202,20 +202,21 @@ This is a dynamic encoding, that is, it can be called with an integer to define
 
 -----
 
-### Vigenere Cipher
+### Playfair Cipher
 
-This is a dynamic encoding, that is, it holds the key. There is no default key, meaning that `vigenere` as the encoding scheme throws a `LookupError` indicating that the _key must be a non-empty alphabetic string_.
+The Playfair cipher is a symmetric encryption method using polygram substitution with bigrams (pairs of letters), invented in 1854 by Charles Wheatstone, but popularized by Lord Playfair.
 
 **Codec** | **Conversions** | **Aliases** | **Comment**
 :---: | :---: | --- | ---
-`vigenere` | text <-> Vigenere ciphertext | `vigenere-abcdef`, `vigenere_MySuperSecret` | key only consists of characters, not digits
+`playfair` | text <-> Playfair ciphertext | `playfair`, `playfair-playfairexample`, `playfair-keyword` | Dynamic key parameter ; letters only ; `J` is normalized to `I`
 
 ```python
->>> codext.encode("This is a test !", "vigenere-abababa")
-'Tiit it a tfsu !'
->>> codext.encode("This is a test !", "vigenere_MySuperSecret")
-'Ffam xw r liuk !'
->>> codext.decode("Tiit it a tfsu !", "vigenere-abababa")
+>>> codext.encode("HIDETHEGOLDINTHETREESTUMP", "playfair-playfairexample")
+'BMODZBXDNABEKUDMUIXMMOUVIF'
+>>> codext.decode("BMODZBXDNABEKUDMUIXMMOUVIF", "playfair-playfairexample")
+'HIDETHEGOLDINTHETREXESTUMP'
+>>> codext.decode(codext.encode("INSTRUMENT", "playfair-keyword"), "playfair-keyword")
+'INSTRUMENT'
 ```
 
 -----
@@ -238,4 +239,3 @@ This is a dynamic encoding, that is, it can be called with an integer to define
 >>> codext.encode("~bcy*cy*k*~oy~", "xor-10")
 'this is a test'
 ```
-

src/codext/crypto/__init__.py

@@ -10,6 +10,4 @@
 from .rot import *
 from .scytale import *
 from .shift import *
-from .vigenere import *
 from .xor import *
-