Python 3 and base64 encoding of a binary file

Question

I'm new to Python and I do have an issue that is bothering me.

I use the following code to get a base64 string representation of my zip file.

with open( "C:\\Users\\Mario\\Downloads\\exportTest1.zip",'rb' ) as file:
    zipContents = file.read()
    encodedZip = base64.encodestring(zipContents)

Now, if I output the string it is contained inside a b'' representation. This for me is not necessary and I would like to avoid it. Also it adds a newlines character every 76 characters which is another issue. Is there a way to get the binary content and represent it without the newline characters and trailing and leading b''?

Just for comparison, if I do the following in PowerShell:

$fileName = "C:\Users\Mario\Downloads\exportTest1.zip"
$fileContentBytes = [System.IO.File]::ReadAllBytes($fileName)
$fileContentEncoded = [System.Convert]::ToBase64String($fileContentBytes)

I do get the exact string I'm looking for, no b'' and no \n every 76 chars.

@PadraicCunningham thus? Isn't that what is suggested to be done while managing binary files? Do you have an example on how to correctly encode a binary file and represent it as base64 string? — Mario Majcica
– Mario Majcica, Commented Jun 21, 2016 at 12:47
docs.python.org/3.5/library/base64.html#base64.encodebytes, if you don't want bytes you will have to decode — Padraic Cunningham
– Padraic Cunningham, Commented Jun 21, 2016 at 12:55

Community · Accepted Answer · 2020-06-20 09:12:55Z

35

From the base64 package doc:

base64.encodestring:

"Encode the bytes-like object s, which can contain arbitrary binary data, and return bytes containing the base64-encoded data, with newlines (b"\n") inserted after every 76 bytes of output, and ensuring that there is a trailing newline, as per RFC 2045 (MIME)."

You want to use

base64.b64encode:

"Encode the bytes-like object s using Base64 and return the encoded bytes."

Example:

import base64

with open("test.zip", "rb") as f:
    encodedZip = base64.b64encode(f.read())
    print(encodedZip.decode())

The decode() will convert the binary string to text.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Jun 21, 2016 at 12:54

Simon Kirsten

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1 Comment

Mario Majcica Over a year ago

This solves the problem with \n but I still do see the leading b' character. Should I just remove it manually with [:-1] or there is a cleaner way?

gre_gor · Accepted Answer · 2016-09-20 14:43:44Z

17

Use b64encode to encode without the newlines and then decode the resulting binary string with .decode('ascii') to get a normal string.

encodedZip = base64.b64encode(zipContents).decode('ascii')

edited Sep 20, 2016 at 14:43

answered Jun 21, 2016 at 12:55

gre_gor

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