# garbled_circuit.py
from Crypto.Random import get_random_bytes
from Crypto.Random import random
import hashlib

def sample_wirekey():
  key = b"wire key:  " 
  key += get_random_bytes(32 - len(key))
  return key

def sample_wirekey_pair(): 
  return [sample_wirekey() for _ in range(2) ]

def encrypt(k1, k2, m):
  h = hashlib.sha256()
  h.update(k1+k2)
  pad = h.digest()
  return bytes([ pad[i] ^ m[i] for i in range(len(m))])

def decrypt(k1, k2, c):
  h = hashlib.sha256()
  h.update(k1+k2)
  pad = h.digest()
  return bytes([ pad[i] ^ c[i] for i in range(len(c))])

def or_table(wire_left, wire_right, wire_out): 
  enc_table = [None]*4
  for x0 in range(2): 
    for x1 in range(2):
      y = x0 or x1
      c = encrypt( wire_left[x0], wire_right[x1], wire_out[y])
      enc_table[x0*2 + x1] = c

  r = random.randrange(4)
  shift_table = [enc_table[(i+r)%4] for i in range(4)]
  return shift_table