Crypt

script1.py

from math import *

def divide(a,b):
  return a//b,a%b

def get_bezout(a,b):
  rnm2=a
  rnm1=b
  unm2=1
  unm1=0
  vnm2=0
  vnm1=1
  
  i=0
  
  while True:
    i+=1
    
    nq,nr=divide(rnm2,rnm1)
    if nr==0:
      return rnm1,unm1,vnm1,i
    
    rnm2,rnm1=rnm1,nr
    unm2,unm1=unm1,unm2-nq*unm1
    vnm2,vnm1=vnm1,vnm2-nq*vnm1

def get_inverse(a,n):
  r,u,v,i=get_bezout(n,a)
  
  return u%n

def mod_power(a,b,n):
  bin_data=[int(i) for i in bin(b)[2:]]
  bin_data.reverse()
  
  exp=a
  v=1
  for i in range(len(bin_data)):
    if bin_data[i]:
      v*=exp
      v%=n
    exp**=2
    exp%=2
  return v

def factors(n):
  sqrtv=int(sqrt(n))

  factors=[]
  
  for i in range(1,sqrtv+1):
    if n%i==0:
      factors.append(i)
  
  r=[n//i for i in factors if not n==i**2]
  r.reverse()
  return factors+r

def prem_factors(n):
  facts=factors(n)
  
  p_facts=[]
  
  for f in facts:
    if len(factors(f))==2:
      i=0
      df=f
      while n%df==0:
        i+=1
        df*=f
      p_facts.append((f,i))
  
  return p_facts

class Key():
  def __init__(self,value,mod):
    self.value=value
    self.mod=mod
  
  def is_valid(self):
    return len(factors(self.mod))==4
  
  def get_phi(self):
    pf1,pf2=prem_factors(self.mod)
    return (pf1[0]-1)*(pf2[0]-1)
    
  def encode(self,data):
    return mod_power(data,self.value,self.mod)
  
  def get_opposite_key(self):
    return Key(get_inverse(self.value,self.get_phi()),self.mod)