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cours/crypto/algo.py
2025-03-18 15:38:06 +01:00

63 lines
1.5 KiB
Python

def est_premier(n):
"""Vérifie si un nombre est premier."""
if n < 2:
return False
for i in range(2, int(n**0.5) + 1):
if n % i == 0:
return False
return True
def liste_premier_inf(n):
return [i for i in range(2, n+1) if est_premier(i)]
def pgcd(a, b):
while b:
a, b = b, a % b
return a
def cle_publique_possible(a, b):
n = a * b
return [i for i in range(1, n) if pgcd(i, n) == 1]
def inverse(e, n):
t, newt = 0, 1
r, newr = n, e
while newr != 0:
quotient = r // newr
t, newt = newt, t - quotient * newt
r, newr = newr, r - quotient * newr
if r > 1:
raise ValueError("L'inverse modulaire n'existe pas.")
if t < 0:
t += n
return t
def chaine_en_liste(chaine):
return [ord(c) for c in chaine]
def chiffre(e, N, liste):
return [pow(x, e, N) for x in liste]
def dechiffre(d, N, liste):
return [pow(x, d, N) for x in liste]
def liste_en_chaine(liste):
return ''.join(chr(x) for x in liste)
cle = 17873
a, b = 61, 53
N = a * b
phi = (a - 1) * (b - 1)
e = 18607
print(N)
d = inverse(e, phi)
message = "「有時,沒有人期待能做出什麼的人,卻完成了沒有人能想像的事。」"
message_code = chaine_en_liste(message)
message_chiffre = chiffre(e, N, message_code)
message_dechiffre = dechiffre(d, N, message_chiffre)
message_final = liste_en_chaine(message_dechiffre)
print("Message initial:", message)
print("Message chiffré:", message_chiffre)
print("Message déchiffré:", message_final)