import sys,math,random,binascii as ba,os
from struct import unpack as u
from struct import pack
is2 = sys.version_info[0]<3
def bt(b):
	if is2:
		return b
	return ord(b)
def b2i(b):
	return int(ba.b2a_hex(b),16)
def i2b(i):
	h='%x'%i
	if len(h)%2==1:
		h ='0'+h
	if not is2:
		h=h.encode('utf-8')
	return ba.a2b_hex(h)
def rs(a,o):
	if a[o]==bt(pack('B',0x81)):
		return(u('B',a[o+1])[0],2+o)
	elif a[o] == bt(pack('B',0x82)):
		return(u('>H',a[o+1:o+3])[0],3+o)
def ri(b,o):
	i,o =rs(b,o)
	return(b[o:o+i],o+i)
def b2me(b):
	if b[0]!=bt(pack('B',0x30)):
		return(None,None)
	_,o=rs(b,1)
	if b[o]!=bt(pack('B',2)):
		return(None,None)
	(m,o)=ri(b,o+1)
	if b[o]!=bt(pack('B',2)):
		return(None,None)
	e=b[o+2:]
	return(b2i(m),b2i(e))
def der2me(d):
	if d[0]!=bt(pack('B',0x30)):
		return(None,None)
	_,o=rs(d,1)
	while o<len(d):
		if d[o]==bt(pack('B',0x30)):
			o+=u('B',d[o+1:o+2])[0]
		elif d[o]==bt(pack('B',0x05)):
			o+=2
		elif d[o]==bt(pack('B',0x03)):
			_,o=rs(d,o+1)
			return b2me(d[o+1:])
		else:
			return(None,None)
def rsa_enc(der,msg):
	m,e=der2me(der)
	h=pack('BB',0,2)
	d=pack('B',0)
	l=256-len(h)-len(msg)-len(d)
	p=os.urandom(512).replace(pack('B',0),pack(''))
	return i2b(pow(b2i(h+p[:l]+d+msg),e,m))