Encrypting a message using secret key in python

Question

I need to encrypt a message using a secret key and return the message. I tried this and I got the correct output.

def my_encryption(some_string):
    character_set= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 "
    secret_key="    Dd18Abz2EqNPW hYTOjBvtVlpXaH6msFUICg4o0KZwJeryQx3f9kSinRu5L7cGM"
    m=some_string
    k=m.translate({ord(x): y for (x, y) in zip(character_set,secret_key )})
    return m

print(my_encryption("Lets meet at the usual place at 9 am"))

The output I got is

oABjMWAABMDBMB2AMvjvDPMYPD1AMDBMGMDWB

and this is correct. I would like to know, will there be any other way to do this with out using translate?. I am curious to know the alternate ways. I will be glad to know. Thank you.

Answer 1

you can use a simple dictionary

def my_encryption(some_string):
    character_set= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 "
    secret_key=    "Dd18Abz2EqNPW hYTOjBvtVlpXaH6msFUICg4o0KZwJeryQx3f9kSinRu5L7cGM"
    table = {x: y for (x, y) in zip(character_set,secret_key )}
    return "".join( map(lambda x:table.get(x,x),some_string) )

the get method can receive 2 arguments, the first is the key to search and the second is a value to return in case that the key is not present, in this case assign that as x to leave that unchanged

here a test

>>> my_encryption("Lets meet at the usual place at 9 am")
'oABjMWAABMDBMB2AMvjvDPMYPD1AMDBMGMDW'
>>> 

this is usually the first thing that come to my mind when I want to do this simple substitution cipher.

and the inverse is as simple as invert key-value

def my_decription(some_string):
    character_set= "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789 "
    secret_key=    "Dd18Abz2EqNPW hYTOjBvtVlpXaH6msFUICg4o0KZwJeryQx3f9kSinRu5L7cGM"
    table = {x: y for (x, y) in zip(character_set,secret_key )}
    return "".join( map(lambda x:table.get(x,x),some_string) )

>>> my_decription('oABjMWAABMDBMB2AMvjvDPMYPD1AMDBMGMDW')
'Lets meet at the usual place at 9 am'
>>> 

Answer 2

A simple solution I use when making things less plain text is base64 module. This is not encryption by any means. Just makes the text a little harder to read:

>>> import base64
>>> base64.b64encode(b'This is a secret.')
b'VGhpcyBpcyBhIHNlY3JldC4='
>>> base64.b64decode(b'VGhpcyBpcyBhIHNlY3JldC4=').decode('utf-8')
'This is a secret.'