From: Clifford Heath <no@...>
Date: 2010-08-20T10:25:05+09:00
Subject: Re: Is there any clever way to encode the uuid string with base64?

Chuck Remes wrote:
> On Aug 19, 2010, at 11:19 AM, Cyril.Liu wrote:
>> But the string is too long for me, i want to encode it with base64.
>> Is any clever way to do this?
> If anything, base64 encoding will make it *longer*. 

Not if he converts it to binary first.

Here's one I made earlier, not base64 though; this is base91.
It turns UUIDs into 20 printable ASCII bytes.
You can change the reference string to whatever you like.
I use sysuuid (gem install it), but you make get uuids elsewhere.

require 'sysuuid'

class Integer
  def base(b)
    self < b ? [self] : (self/b).base(b) + [self%b]
  end
end

# If we only used upper, lower and digits (base 62), it'd need 22 characters and be more easily copy-pastable
BASE91 = '!#$%&()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`abcdefghijklmnopqrstuvwxyz{|}~'

uuid = sysuuid.gsub(/-/,'').hex
uuid20 = uuid.base(91).map{|i| BASE91[i].chr }*''
uuid_again = uuid20.split(//).inject(0){|i,e| i*91 + BASE91.index(e[0]) }

Clifford Heath.