From ea4049863f8cd9231646d366e36ddfe5c2c47f30 Mon Sep 17 00:00:00 2001
From: "flyingscorpio@pinebookpro" <tfranken@protonmail.com>
Date: Tue, 25 Jan 2022 10:52:19 +0100
Subject: [PATCH] =?UTF-8?q?Add=20d=C3=A9chiffrement=20to=20chiffrement=5Fa?=
 =?UTF-8?q?ffine?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 algebre-non-lineaire/chiffrement_affine.py | 44 ++++++++++++++++++----
 1 file changed, 37 insertions(+), 7 deletions(-)

diff --git a/algebre-non-lineaire/chiffrement_affine.py b/algebre-non-lineaire/chiffrement_affine.py
index 2f0c151..2820908 100755
--- a/algebre-non-lineaire/chiffrement_affine.py
+++ b/algebre-non-lineaire/chiffrement_affine.py
@@ -2,24 +2,41 @@
 
 """Chiffrement affine"""
 
+import sys
+
 from inverse import inverser
+from oppose import opposer
 
 
 def main():
+    if len(sys.argv) == 2:
+        if sys.argv[1] == "chiffrer":
+            action = "chiffrer"
+        elif sys.argv[1] == "déchiffrer":
+            action = "déchiffrer"
+    else:
+        action = input("Chiffrer ou déchiffrer ? ")
+
     alphabet = input("Alphabet pour le chiffrement affine, terminez par Entrée : ")
-    kc = input(
+    a, b = input(
         "Clé de chiffrement (deux nombres séparés par un espace, exemple: 2 4) "
     ).split(" ")[:2]
-    kc = tuple(int(i) for i in kc)
-    a, b = kc
+    kc = (int(a), int(b))
     inv_a = inverser(a)
+    if not inv_a:
+        print(f"{a} doit être inversible")
+        return
     op_b = opposer(b)
     kd = (inv_a, (inv_a * op_b) % n)
 
-    message = input("Message à chiffrer : ")
-
-    c = chiffrer(message, alphabet, kc)
-    print(c)
+    if action == "chiffrer":
+        message = input("Message à chiffrer : ")
+        c = chiffrer(message, alphabet, kc)
+        print(c)
+    elif action == "déchiffrer":
+        message = input("Message à déchiffrer : ")
+        m = dechiffrer(message, alphabet, kd)
+        print(m)
 
 
 def chiffrer(message: str, alphabet: str, cle: tuple[int, int]):
@@ -34,5 +51,18 @@ def chiffrer(message: str, alphabet: str, cle: tuple[int, int]):
     return output
 
 
+def dechiffrer(message: str, alphabet: str, cle: tuple[int, int]):
+    n = len(alphabet)
+    a, b = cle
+    output = ""
+    for symbol in message:
+        c = list(alphabet).index(symbol)
+        m = (a * c + a * b) % n
+        output += alphabet[m]
+
+    return output
+
+
+
 if __name__ == "__main__":
     main()