BKU-CTF

Crypto0.py

e = 0x10001
n = 55089599753625499150129246679078411260946554356961748980861372828434789664694269460953507615455541204658984798121874916511031276020889949113155608279765385693784204971246654484161179832345357692487854383961212865469152326807704510472371156179457167612793412416133943976901478047318514990960333355366785001217
q = 7422236843002619998657542152935407597465626963556444983366482781089760759017266051147512413638949173306397011800331344424158682304439958652982994939276427
c = 33062272351573218250384115704487361063970465004033740168733959927707721053321054975845636421337650298670338055101957913137486876401007806540788449215177115739842456860057795240129932234489439409388612936981938930876353938688227847808194010536300529961489751250254640618262254364661940751727869020817391566773

p = n/q
phi = (p-1)*(q-1)

def egcd(a, b):
	if a == 0:
		return (b, 0, 1)
	g, y, x = egcd(b%a,a)
	return (g, x - (b//a) * y, y)

def modinv(a, m):
	g, x, y = egcd(a, m)
	if g != 1:
		raise Exception('No modular inverse')
	return x%m

d = modinv(e,phi)
m = pow(c,d,n)
print hex(m)[2:-1].decode('hex')
# WELCOME_TO_THE_KINGDOM_OF_CRYPTOGRAPHY!!!