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elgamal.py

 from typing import Tuple
 from random import randint
 from sys import argv
-from math import sqrt
+from math import sqrt, gcd
 
 INPUT_NAME="fichier.txt"
 SIGNATURE_NAME="fichier.signed.txt"
@@ -113,12 +113,31 @@ def get_random_generator(p: int) -> int:
     return generators[1]
 
 def generate_key_pair() -> Tuple[Privkey, Pubkey]:
-    p = get_random_prime(1000, 10_000)
-    g = get_random_generator(p)
-    a = randint(0, p - 1)
+    # p = get_random_prime(1000, 10_000)
+    # g = get_random_generator(p)
+    # a = randint(0, p - 1)
+    p = 7297
+    g = 14
+    a = 7057
     A = pow(g, a, p)
     return Privkey(p, g, a), Pubkey(p, g, A)
 
+def xgcd(a,b):
+    prevx , x = 1 , 0 
+    prevy , y = 0 , 1 
+    while b:
+        q = a//b
+        x, prevx = prevx - q*x, x 
+        y, prevy = prevy - q*y, y
+        a, b = b, a % b
+    return a, prevx, prevy
+
+def generate_k(p: int) -> int:
+    k = randint(1, p - 2)
+    while gcd(k, p - 1) != 1:
+        k = randint(1, p - 2)
+    return k
+
 def main(mode):
     if mode == 0:
         # open the fichier.txt file and read its content into a string
@@ -128,7 +147,8 @@ def main(mode):
 
         # algorithm
         privkey, pubkey = generate_key_pair()
-        signature = sign(hash(m), 5, privkey)
+        k = generate_k(privkey.p)
+        signature = sign(hash(m), k, privkey)
 
         # write our files
         pubkey.write(PUBKEY_FILE)

fichier.signed.txt

-1117 2077
+3621 5011
 Il faut pas respirer la compote, ça fait tousser.
\ No newline at end of file

privkey.txt

-6659 6 337
+7297 14 7057
\ No newline at end of file

pubkey.txt

-6659 6 1575
+7297 14 1356
\ No newline at end of file