Why does base64 encode return bytes instead of string directly?

Question

import base64
base64.b64encode(b'bytes required')

>>>b'Ynl0ZXMgcmVxdWlyZWQ='

If I understand correctly, base64 is a bytes <----> string notation. Then why doesn't it give me string 'Ynl0ZXMgcmVxdWlyZWQ=' directly?

Or does it expect me to do some decoding furthermore?

Like b'Ynl0ZXMgcmVxdWlyZWQ='.decode('ascii') or
b'Ynl0ZXMgcmVxdWlyZWQ='.decode('utf-8') ? But they result in the same thing.

codes of `ascii` symbols are same in `utf-8`, that's why result is same. — Olvin Roght, Aug 15 '19 at 07:42
@OlvinRoght Yes and base64 uses only `ascii` characters, why doesn't it gives me string directly? Why would I need the binary result? I wonder :( — Rick, Aug 15 '19 at 07:43

AlanSTACK · Accepted Answer · 2023-02-04T19:03:32.357

2

You are correct that base64 is meant to be a textual representation of binary data.

However, you are neglecting constraints on the actual implementation side of things.

import sys

>>> sys.getsizeof("Hello World")
60
>>> sys.getsizeof("Hello World".encode("utf-8"))
44

str objects simply take up more system resources than bytes. This overhead can lead to non-trivial degradation in performance when working with larger bodies of base64 encoded data.

I also suspect that since the original python module was ported from python2.7 (which did not distinguish between str and bytes), that this might also just be a legacy part of the language.

edited Feb 04 '23 at 19:03

answered Aug 15 '19 at 07:50

AlanSTACK

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I thought utf-8 was the default encoding? – xrisk Aug 15 '19 at 07:51
Thanks. I didn't know that "str objects simply take up more system resources than bytes". Good to know it :) – Rick Aug 15 '19 at 08:09

Why does base64 encode return bytes instead of string directly?

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