so, i tried to do it. Hope in future it'll be easier to do cryptographic alghorithms

rsa-mini.py

def GCD(a,b):
    g = [max(a,b),min(a,b)]
    mass = [[max(a,b),min(a,b)]]
    while g[0] != 0 and g[1] != 0:
        g[0], g[1] = g[1], g[0] % g[1]
        mass.append([g[0],g[1]])
    return mass, g[0]

def euclid_ext(a, b):
    if b == 0:  
        return a, 1, 0
    else:
        d, x, y = euclid_ext(b, a % b)
        return d, y, x - y * (a // b)

def endcrypt(m,ed,N):
    return m**ed % N

p,q = map(int,input("Please, enter prime numbers p and q: ").split())
N, phiN = p * q, (p-1) * (q-1) 

print(f"Your N = {N}, your phi(N) = {phiN}.")

print("Now you need to choose open key e which satisfies the condiction 1 < e < phi(N) and e should be coprime with phi(GCD = 1)")
e = int(input())
if GCD(e,phiN)[1] != 1:
    e = int(input("Open key e isn't satisfie the condiction, choose new: "))

_,_,c = euclid_ext(phiN,e)
if c > 0:
    d = c
else:
    d = phiN + c
print(d)
message = int(input("Enter message u wanna encode(only numbers now):"))
em = endcrypt(message,e,N)
dem = endcrypt(em,d,N)
print("Encrypted message: " + str(em))

print("Decrypted message: " + str(dem))
a = input()