5th_python.py

p = 11
q = 13
n = p * q
phi_n = (p-1) * (q-1)

e = 7

d = 0
mod = 0
while True:
    d += 1
    mod = (e * d) % phi_n
    if mod == 1:
        break

print(d)

#encryption
# C = P^e mod n

plain = "Hello world"
plain_list = [ord(x) for x in plain]

print(plain_list)

cipher = []
for i in plain_list:
    x = (i ** e) % n
    cipher.append(int(x))

print(cipher)

#decryption
# P = C*d mod n

decryted = []
for i in cipher:
    x = (i ** d) % n
    decryted.append(int(x))

print('plain text', plain_list)
print('cipher text', cipher)
print('decryted text', decryted)

print([chr(x) for x in decryted])
decryted_text = ([chr(x) for x in decryted])
print(decryted_text)