Decode a base64 encoded JSON string generated from JavaScript in Python

Question

Take this base64-encoded JSON string generated from JavaScript using JSON.stringify and btoa:

btoa(JSON.stringify({"é": "è"}))
"eyLpIjoi6CJ9"

I'm trying to decode it from Python. I'm doing:

>>> import base64
>>> import json
>>> json.loads(base64.b64decode("eyLpIjoi6CJ9"))

I'm getting a UnicodeDecodeError:

UnicodeDecodeError: 'utf-8' codec can't decode byte 0xe9 in position 2: invalid continuation byte

What is the right way to properly decode this in Python?

Note: I'm using base64 encoding so this can be safely passed as an URL query string parameter.

Thanks!

staylor · Accepted Answer · 2020-11-30 10:55:03Z

1

You can also do in JavaScript

    btoa(unescape(encodeURIComponent(JSON.stringify({"é": "è"}))))
    base64 output: eyLDqSI6IsOoIn0=

though I think btoa works on just the extended ascii table, not all unicode characters.

Then in Python

    json.loads(base64.b64decode("eyLDqSI6IsOoIn0=")
    prints: {'é': 'è'}

answered Nov 30, 2020 at 10:55

staylor

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