Add autoclave (autokey) cipher codec

Co-authored-by: dhondta <9108102+dhondta@users.noreply.github.com>
Agent-Logs-Url: https://github.com/dhondta/python-codext/sessions/4af53d1f-ef97-4bc3-9dd3-c6b23cdd761d

Author: Copilot

src/codext/crypto/__init__.py

@@ -1,6 +1,7 @@
 # -*- coding: UTF-8 -*-
 from .affine import *
 from .atbash import *
+from .autoclave import *
 from .bacon import *
 from .barbie import *
 from .citrix import *

src/codext/crypto/autoclave.py

@@ -0,0 +1,84 @@
+# -*- coding: UTF-8 -*-
+"""Autoclave Cipher Codec - autoclave content encoding.
+
+The Autoclave (Autokey) cipher is a variant of the Vigenere cipher where the key
+is extended by appending the plaintext to the initial key (key+plaintext), making
+the key stream as long as the message itself.
+
+This codec:
+- en/decodes strings from str to str
+- en/decodes strings from bytes to bytes
+- decodes file content to str (read)
+- encodes file content from str to bytes (write)
+
+Reference: https://www.dcode.fr/autoclave-cipher
+"""
+from string import ascii_lowercase as LC, ascii_uppercase as UC
+
+from ..__common__ import *
+
+
+__examples__ = {
+    'enc(autoclave)':             None,
+    'enc(autoclave-queenly)':     {'ATTACKATDAWN': 'QNXEPVYTWTWP'},
+    'enc-dec(autoclave-key)':     ['hello world', 'ATTACK AT DAWN', 'Test 1234!', 'Mixed Case 123'],
+}
+__guess__ = ["autoclave-key", "autoclave-secret", "autoclave-password"]
+
+
+def __check(key):
+    key = key.lower()
+    if not key or not key.isalpha():
+        raise LookupError("Bad parameter for encoding 'autoclave': key must be a non-empty alphabetic string")
+    return key
+
+
+def autoclave_encode(key):
+    def encode(text, errors="strict"):
+        k = __check(key)
+        text_str = ensure_str(text)
+        alpha_chars = [c.lower() for c in text_str if c in LC or c in UC]
+        key_stream = k + "".join(alpha_chars)
+        result = []
+        ki = 0
+        for c in text_str:
+            if c in LC:
+                result.append(LC[(ord(c) - ord('a') + ord(key_stream[ki]) - ord('a')) % 26])
+                ki += 1
+            elif c in UC:
+                result.append(UC[(ord(c) - ord('A') + ord(key_stream[ki]) - ord('a')) % 26])
+                ki += 1
+            else:
+                result.append(c)
+        r = "".join(result)
+        return r, len(r)
+    return encode
+
+
+def autoclave_decode(key):
+    def decode(text, errors="strict"):
+        k = __check(key)
+        text_str = ensure_str(text)
+        result = []
+        key_stream = list(k)
+        ki = 0
+        for c in text_str:
+            if c in LC:
+                dec_c = LC[(ord(c) - ord('a') - (ord(key_stream[ki]) - ord('a'))) % 26]
+                result.append(dec_c)
+                key_stream.append(dec_c)
+                ki += 1
+            elif c in UC:
+                dec_c = UC[(ord(c) - ord('A') - (ord(key_stream[ki]) - ord('a'))) % 26]
+                result.append(dec_c)
+                key_stream.append(dec_c.lower())
+                ki += 1
+            else:
+                result.append(c)
+        r = "".join(result)
+        return r, len(r)
+    return decode
+
+
+add("autoclave", autoclave_encode, autoclave_decode,
+    r"auto(?:clave|key)(?:[-_]cipher)?(?:[-_]([a-zA-Z]+))?$", penalty=.1)