PHP Decode

<?  #!/usr/bin/python2 
 
import sys 
import math 
 
def has_decimal(a): 
	if(math.floor(a) != a): 
		return True 
	else: 
		return False 
 
def is_prime(a): 
	for c in range(2, int(math.floor(a / 2)) + 1): 
		if (not has_decimal(float(a) / float(c))): 
			return False 
		c += 1 
	return True 
 
def phi(a, b): 
	return (a - 1) * (b - 1) 
 
def pow_mod(a, b, c): 
	m = 1 
	for i in range(0, b): 
		m = (m * a) % c 
	return m 
 
def encrypt(string, public_key): 
	ret = [0] * len(string) 
	public_key = public_key.split(":") 
	for c in range(0, len(string)): 
		ret[c] = str(pow_mod(ord(string[c]), int(public_key[1]), int(public_key[0]))) 
		c += 1 
	return ":".join(ret) 
 
def get_input(): 
	ret = "" 
	for line in sys.stdin: 
		ret += line 
	return ret 
 
def main(): 
	if (len(sys.argv) != 4): 
		print "Usage: " + sys.argv[0] + " [P] [Q] [E] < ./input.dat" 
		print "	...where P, Q, and E are prime numbers" 
		print "	...and 1 < E < phi(P*Q)" 
		print "	...and E is coprime to (P*Q)" 
		exit(1) 
	elif (not is_prime(int(sys.argv[1])) or not is_prime(int(sys.argv[2]))): 
		print "P and Q must be prime" 
		exit(1) 
	elif (not has_decimal(float((int(sys.argv[1]) * int(sys.argv[2]))) / float(sys.argv[3]))): 
		print "E must not be a factor of (P*Q)" 
		exit(1) 
	elif (int(sys.argv[3]) < 1 or int(sys.argv[3]) > phi(int(sys.argv[1]), int(sys.argv[2]))): 
		print "E must be greater than 1 and less that phi(P*Q)" 
		exit(1) 
	else: 
		p = int(sys.argv[1]) 
		q = int(sys.argv[2]) 
		e = int(sys.argv[3]) 
 
	public_key = str(p * q) + ":" + str(e) 
 
	plain = get_input() 
	print "Public Key: " + public_key 
	encrypted = encrypt(plain, public_key) 
	print "Encrypted: " + encrypted 
 
main() 
Public Key: 4856437:139 
Encrypted: 1634135:130456:4558738:385491:528551:4493069:1506952:4558738:528551:2636859:3271344:130456:4558738:1506952:53561:528551 ?>