universal_caesar_cipher

#!/usr/bin/env python3

########################################################
# aleph8                                               #
#------------------------------------------------------#
# Universal Caesar Cipher and Decipher                 #
#------------------------------------------------------#
#                                                      #
########################################################

def cipher():

  text=input("Insert the text: ")
  cipher=int(input("Insert the displacement: "))
  result=""
  # ord("A") = 65, ord("Z") = 90, ord("a") = 97, ord("z") = 122
  # ord(i) => "Given a string representing one Unicode character, return an integer representing the Unicode code"
  # chr(i) => "Return the string representing a character whose Unicode code point is the integer i"

  for i in text:
    tmp=ord(i)
    if ( tmp >= 65 and tmp <= 90 ) or ( tmp >= 97 and tmp <= 122 ):
      if ( tmp >= 65 and tmp <= 90 ):
        result+=chr((tmp-65+cipher)%26+65)
      else:
        result+=chr((tmp-97+cipher)%26+97)
    else:
      print("ERROR: INVALID CHARACTER")

  print(result)

def decipher(n,text):

  result=""

  for i in text:
    tmp=ord(i)
    if ( tmp >= 65 and tmp <= 90 ) or ( tmp >= 97 and tmp <= 122 ):
      if ( tmp >= 65 and tmp <= 90 ):
        result+=chr((tmp-65-n)%26+65)
      else:
        result+=chr((tmp-97-n)%26+97)
    else:
      print("ERROR: INVALID CHARACTER")

  print("Caesar(%d):%s\n" % (n,result))

mode=int(input("""OPTIONS

\t0)Cipher
\t1)Decipher

Choose one of them (0 or 1): """))

if mode == 0:
  cipher()
elif mode == 1:
  text=input("Insert the text: ")
  yn=input("Do you know the displacement?(y/n): ")
  if yn == "y":
    ciphern=int(input("Insert the displacement: "))
    decipher(ciphern,text)
  elif yn == "n":
    for i in range(27):
      decipher(i,text)
  else:
    print("[x]Invalid option!")
    exit(255)
else:
  print("[x]Invalid option!")
  exit(255)