Encode IPv4 address into 6 or less ASCII Printable Characters

Question

Is it possible encode IPV4 into 6 or less ASCII Printable Characters to create an ultra portable ID that users can tell to each other, which really represents an IP.

You can't compress such small data. But you can represent it in another base, per example base16, hexadecimal, an IP would be like C0A80A01 — Gusman, Mar 18 '18 at 23:54
There are 95 printable characters. With 6 of them, there are about 7.3e11 possible combinations. There are only about 4.3e9 IPv4 addresses, so yes it is possible. — Dave M, Mar 19 '18 at 00:01
You could theoretically get away with only 5 printable characters, there would be about 7 billion combinations (you only need 4.3 billion) — Dave M, Mar 19 '18 at 00:04
@DaveM You could even reduce it to 85 different characters to express all 4.3 billion combinations with just 5 character positions (as 85^5 = 4.4 billion different combinations). — ckuri, Mar 19 '18 at 00:30
isnt it obvious im just using compress as a way to get my idea across? I explain in the body — DOSLuke, Mar 19 '18 at 00:31

TheGeneral · Accepted Answer · 2018-03-20T02:32:54.230

You could try this base95 implementation it will get it down to 5 printable characters

public static class Base95Extension
{
   private const string PrintableChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ !?\"'`^#$%@&*+=/.,:;|\\_<>[]{}()~-";

   private const int Length = 95;

   public static uint ToUInt32(this IPAddress ip)
   {
      return BitConverter.ToUInt32(ip.GetAddressBytes(), 0);
   }

   public static IPAddress ToIpAddress(this uint source)
   {
      return new IPAddress(BitConverter.GetBytes(source));
   }

   public static string ToBase95(this IPAddress ip)
   {
      var num = ip.ToUInt32();
      var result = string.Empty;
      uint index = 0;

      while (num >= Math.Pow(Length, index))
      {
         index++;
      }

      while (index-- > 0)
      {
         var pow = (uint)Math.Pow(Length, index);
         var div = num / pow;
         result += PrintableChars[(int)div];
         num -= pow * div;
      }

      return result;
   }

   public static IPAddress ToIpAddress(this string s)
   {
      uint result = 0;

      var chars = s.Reverse()
                   .ToArray();

      for (var i = 0; i < chars.Length; i++)
      {
         var pow = Math.Pow(Length, i);
         var ind = PrintableChars.IndexOf(chars[i]);
         result += (uint)(pow * ind);
      }

      return new IPAddress(BitConverter.GetBytes(result));
   }

}

Usage

var ip = "255.255.255.255";
var ipAddress = IPAddress.Parse(ip);
var result = ipAddress.ToBase95();
Console.WriteLine(ip);
Console.WriteLine(result);
Console.WriteLine(result.ToIpAddress());

Output

255.255.255.255
Q#F 5
255.255.255.255

[Demo Here][1]

You can easily get 6 digits if you use at least 41 different characters as this allows for 41^6=4.7 billion different combinations which is sufficient to cover all 2^32=4.3 billion possible IP addresses. — ckuri, Mar 19 '18 at 00:08
Base64 would be only 6 characters, but this is easier to read and harder to mistype since it uses only the characters 0-9, A-F. — Dave S, Mar 19 '18 at 00:09
Thanks. Ive done the same thing with some similar, if not easier to read code. Ill post when i get home. — DOSLuke, Mar 19 '18 at 00:34
Also you can get rid of the == at the end as its just padding. You can add it later easily. — DOSLuke, Mar 19 '18 at 00:35

score 0 · Answer 2 · answered Mar 19 '18 at 00:08

0

You can either try:

uint iaddress = BitConverter.ToUInt32(IPAddress.Parse(address).GetAddressBytes(), 0);

or use the structure here

or use the formula:

a.b.c.d => a*2^24 + b*2^16 + c*2^8 + d (which I think is faster)

see a similar question with reasonable answers

answered Mar 19 '18 at 00:08

I actually used that im my solution to the problem. After getting the int, i turn it into a byte array and then into base 64 – DOSLuke Mar 19 '18 at 00:39

DOSLuke · Answer 3 · 2018-03-19T03:44:55.373

So I have figured something out. it accomplishes the same thing as Michael Randall's answer, in essence. His is probably more efficient, and uses less dependencies. this is just what I came up with. the main upside I see with mine is less special chars are included in the encoded string, so its easy for people to verbally communicate.

public static string Base64EncodeIP(string ip)
{
    UInt32 ipasint = BitConverter.ToUInt32(IPAddress.Parse(ip).GetAddressBytes(), 0);
    byte[] ipasbytes = BitConverter.GetBytes(ipasint);
    string encodedip = Convert.ToBase64String(ipasbytes);
    return encodedip.Replace("=", "");
}

public static string Base64DecodeIP(string encodedIP)
{
    //re-add however much padding is needed, to make the length a multiple of 4
    if (encodedIP.Length % 4 != 0)
        encodedIP += new string('=', 4 - encodedIP.Length % 4);

    byte[] ipasbytes = Convert.FromBase64String(encodedIP);
    UInt32 ipasint = BitConverter.ToUInt32(ipasbytes, 0);
    return new IPAddress(BitConverter.GetBytes(ipasint)).ToString();
}

EDIT

Links for some code I used:
How to convert an IPv4 address into a integer in C#?
Remove trailing "=" when base64 encoding

side note, if anyone wants to do a speed comparison, plz post the results :) — DOSLuke, Mar 19 '18 at 03:35
you are trying to decode it twice. typo? i think line 36 should use the encode function? it runs perfectly after changing it to the encode function. — DOSLuke, Mar 20 '18 at 02:30

Encode IPv4 address into 6 or less ASCII Printable Characters

3 Answers3

EDIT