Mail extraction problem (something's wrong with split methods)

[Luka Milkovic]

On Sun, 12 Sep 2004 18:11:38 +0200, Diez B. Roggisch wrote:

> Well, you could certainly code around these special cases - however, it
> seems to me that whatever generates this mail is malfunctioning. Not on the
> transport-layer, but from the thing that produces this 
> 
> ---Code block---
> 
> thingy.

The thing that produces this Code block thingy is a /dev/random output.
I'm actually building a primitive One-time pad:) Here is the code (not
translated, but you'll understand I think):

duljina_grupe = 4                                  
dev_random = open("/dev/random")                   
P = select.poll()
P.register(dev_random.fileno(),select.POLLIN)      
grupe = []

while len(grupe) < gener:                          
  grupa = ""
  while len(grupa) < duljina_grupe:
    if P.poll(0.1):                                
      datum = ord(dev_random.read(1))
      if datum < 200:
        grupa+="%2.2d"%(datum%100)                 
    else:                                          
      print "Nedovoljna kolicina entropije u /dev/random! Pomaknite misa"
      print "Za sada generirano %d grupa"%len(grupe)
  grupe.append(int(grupa))

And overlapping it with text transfered in ASCII format:

grupe = []
for char in otv:
  grupe.append(ord(char))
f2 = open("OTpad.pad","r")                         
prvi = pickle.load(f2)
enc_txt = map(lambda x,y: (x or 0) ^ (y or 0),prvi,grupe)

This enc_txt is the thingy which is mailed... Do you see any mistakes?

> What is that actually for? It looks as if  you try to reinvent the wheel
> and produce your own encoding scheme for binary data - instead of doing
> this, I suggest you use one of the several available standards, like
> uuencode or others. These are covered by standard apis in python as well
> as in other languages. Better go for them.


>Straight-line brute forcing it:

>msg = ....     # get the message as a tuple  
>sep = "---Code block---"
>start = msg[1].index(sep)
>data = msg[1][start+1:]
>end = data.index(sep)
>data = data[:end]
>print "".join(data)[1:-1].split(", ")

Thanks Pierre, I'll try something like that later.

Luka