Encode IP address using all printable characters in Python 2.7.x

Question

I would like to encode an IP address in as short a string as possible using all the printable characters. According to https://en.wikipedia.org/wiki/ASCII#Printable_characters these are codes 20hex to 7Ehex.

For example:

shorten("172.45.1.33") --> "^.1 9" maybe.

In order to make decoding easy I also need the length of the encoding always to be the same. I also would like to avoid using the space character in order to make parsing easier in the future.

How can one do this?

I am looking for a solution that works in Python 2.7.x.

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My attempt so far to modify Eloims's answer to work in Python 2:

First I installed the ipaddress backport for Python 2 (https://pypi.python.org/pypi/ipaddress) .

#This is needed because ipaddress expects character strings and not byte strings for textual IP address representations 
from __future__ import unicode_literals
import ipaddress
import base64

#Taken from http://stackoverflow.com/a/20793663/2179021
def to_bytes(n, length, endianess='big'):
    h = '%x' % n
    s = ('0'*(len(h) % 2) + h).zfill(length*2).decode('hex')
    return s if endianess == 'big' else s[::-1]

def def encode(ip):
    ip_as_integer = int(ipaddress.IPv4Address(ip))
    ip_as_bytes = to_bytes(ip_as_integer, 4, endianess="big")
    ip_base85 = base64.a85encode(ip_as_bytes)
    return ip_base

print(encode("192.168.0.1"))

This now fails because base64 doesn't have an attribute 'a85encode'.

Answer 1

An IP stored in binary is 4 bytes.

You can encode it in 5 printable ASCII characters using Base85.

Using more printable characters won't be able to shorten the resulting string more than that.

import ipaddress
import base64

def encode(ip):
    ip_as_integer = int(ipaddress.IPv4Address(ip))
    ip_as_bytes = ip_as_integer.to_bytes(4, byteorder="big")
    ip_base85 = base64.a85encode(ip_as_bytes)
    return ip_base85

print(encode("192.168.0.1"))

Answer 2

I found this question looking for a way to use base85/ascii85 on python 2. Eventually I discovered a couple of projects available to install via pypi. I settled on one called hackercodecs because the project is specific to encoding/decoding whereas the others I found just offered the implementation as a byproduct of necessity

from __future__ import unicode_literals
import ipaddress
from hackercodecs import ascii85_encode

def encode(ip):
    return ascii85_encode(ipaddress.ip_address(ip).packed)[0]

print(encode("192.168.0.1"))

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• https://pypi.python.org/pypi/hackercodecs
• https://github.com/jdukes/hackercodecs