Convert to binary and convert back to strings

[Larry Bates]

Harlin Seritt wrote:
> Hi...
> 
> I would like to take a string like 'supercalifragilisticexpialidocius'
> and write it to a file in binary forms -- this way a user cannot read
> the string in case they were try to open in something like ascii text
> editor. I'd also like to be able to read the binary formed data back
> into string format so that it shows the original value. Is there any
> way to do this in Python?
> 
> Thanks!
> 
> Harlin
> 
I promise you that everything written to a file is done in binary.
Computers don't know how to work with anything BUT binary.  I think
what you want to do is to encrypt/obstifucate the string.  For that
you will need to encrypt the string, write it out, read it back in,
and decrypt it.  If you want it to be REALLY strong use pyCrypto
and something like AES-256.

http://www.amk.ca/python/code/crypto

If you just want to make it somewhat hard for someone to decypher
you can do something like below (sorry I can't remember where I
found this to attribute to someone):
import random
import zlib
import time

def tinycode(key, text, reverse=False):
    rand = random.Random(key).randrange
    if not reverse:
        text = zlib.compress(text)
    text = ''.join([chr(ord(elem)^rand(256)) for elem in text])
    if reverse:
        text = zlib.decompress(text)
    return text

def strToHex(aString):
    hexlist = ["%02X" % ord(x) for x in aString]
    return ''.join(hexlist)

def HexTostr(hString):
    res = ""
    for i in range(len(hString)/2):
        realIdx = i*2
        res = res + chr(int(hString[realIdx:realIdx+2],16))
    return res

if __name__ == "__main__":

    keyStr = "This is a key"
    #testStr = "which witch had which witches wrist watch abc def ghi"

    testStr=time.strftime("%Y%m%d", time.localtime())

    print "String:", testStr
    etestStr = tinycode(keyStr, testStr)
    print "Encrypted string:", etestStr
    hex=strToHex(etestStr)
    print "Hex    : ", hex
    print "Len(hex):", len(hex)
    nonhex=HexTostr(hex)
    #testStr = tinycode(keyStr, etestStr, reverse=True)
    testStr = tinycode(keyStr, nonhex, reverse=True)
    print "Decrypted string:", testStr

WARNING: THIS IS NOT A STRONG ENCRYPTION ALGORITHM.  It is just a
nuisance for someone that really wants to decrypt the string. But
it might work for your application.

-Larry