Hexahexacontadecimal

Hexahexacontadecimal is the most compact way to encode a number into a URL.

Hexahexacontadecimal is a compact format to express a number in a URL. It uses all characters allowed in a URL without escaping -- the unreserved characters -- making it the shortest possible way to express an integer in a URL.

Usage

from hexahexacontadecimal import hexahexacontadecimal_encode_int, hexahexacontadecimal_decode_int

print hexahexacontadecimal_encode_int(302231454903657293676544)  # 'iFsGUkO.0tsxw'
print hexahexacontadecimal_decode_int('iFsGUkO.0tsxw')           # 302231454903657293676544L

Note that urllib.quote escapes the tilde character (~), which is not necessary as of RFC3986.

On the command line

With pyle you can easily use hexahexacontadecimal on the command line.

$ wc -c LICENSE MANIFEST setup.py | pyle -m hexahexacontadecimal -e "'%-10s Hexhexconta bytes:' % words[1], hexahexacontadecimal.hexahexacontadecimal_encode_int(int(words[0]))"
LICENSE    Hexhexconta bytes: MV
MANIFEST   Hexhexconta bytes: 1z
setup.py   Hexhexconta bytes: GI
total      Hexhexconta bytes: ei

Hexahexacontadecimal vs Base 64 in URLs

>>> n = 292231454903657293676544
>>> import base64
>>> urlquote(base64.urlsafe_b64encode(long_to_binary(n)))
'PeHmHzZFTcAAAA%3D%3D'
>>> urlquote(hexahexacontadecimal_encode_int(n))
'gpE4Xoy7fw5AO'

Worst case scenario for plain Base 64:

>>> n = 64 ** 5 + 1
>>> urlquote(base64.urlsafe_b64encode(long_to_binary(n)))
'QAAAAQ%3D%3D'
>>> urlquote(hexahexacontadecimal_encode_int(n))
'ucrDZ'

Worst case for hexahexacontadecimal:

>>> n = 66 ** 5 + 1
>>> urlquote(base64.urlsafe_b64encode(long_to_binary(n)))
'SqUUIQ%3D%3D'
>>> urlquote(hexahexacontadecimal_encode_int(n))
'100001'

That big SHA-512 you always wanted to write in a URL:

>>> n = 2 ** 512
>>> urlquote(base64.urlsafe_b64encode(long_to_binary(n)))
'AQAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA%3D'
>>> urlquote(hexahexacontadecimal_encode_int(n))
'JK84xqGD9FMXPNubPghADlRhBUzlqRscC2h~8xmi99PvuQsUCIB2CHGhMUQR8FLm72.Hbbctkqi89xspay~y4'

Massive savings.

Are the savings really significant?

If you're currently doing your BASE64 encoding the naive way, then yes:

>>> sum(len(urlquote(base64.urlsafe_b64encode(long_to_binary(n)))) for n in xrange(10 ** 5))
531584
>>> sum(len(urlquote(hexahexacontadecimal_encode_int(n))) for n in xrange(10 ** 5))
295578

But what if I use Base64 without padding?

Then the savings are not as significant. But it's still an improvement. Using the code from this StackOverFlow question:

>>> from hexahexacontadecimal.num_encode_base64 import num_encode as num_encode_base64
>>> n = 64 ** 5 + 1
>>> urlquote(num_encode_base64(n))
'BAAAAB'
>>> urlquote(hexahexacontadecimal_encode_int(n))
'ucrDZ'
>>> n = 66 ** 5 + 1
>>> urlquote(num_encode_base64(n))
'BKpRQh'
>>> urlquote(hexahexacontadecimal_encode_int(n))
'100001'
>>> n = 2 ** 512
>>> urlquote(num_encode_base64(n))
'EAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA'
>>> urlquote(hexahexacontadecimal_encode_int(n))
'JK84xqGD9FMXPNubPghADlRhBUzlqRscC2h~8xmi99PvuQsUCIB2CHGhMUQR8FLm72.Hbbctkqi89xspay~y4'
>>> sum(len(urlquote(num_encode_base64(n))) for n in xrange(10 ** 5))
295840
>>> sum(len(urlquote(hexahexacontadecimal_encode_int(n))) for n in xrange(10 ** 5))
295578

Why settle for less than perfect?

Installation

pip install hexahexacontadecimal

Documentation

This file and docstrings.

License

Free to use and modify under the terms of the BSD open source license.

Author

Alexander Ljungberg