Unable to verify Firebase token

Question

I am making an app in flutter which uses Google sign-in. I also have a Django backend linked to the app and I want to verify the user in the Django backend. I found many solutions on the internet but none is working. Probably I am messing up somewhere.

I tried using python-jose for verification and here is the code:

from jose import jwt
import urllib.request, json
token = '<token recieved using await user.getIdToken in flutter>'
target_audience = "<tried projectid/appid>"
certificate_url = 'https://www.googleapis.com/robot/v1/metadata/x509/[email protected]'
response = urllib.request.urlopen(certificate_url)
certs = response.read()
certs = json.loads(certs)
print(certs)
user = jwt.decode(token, certs, algorithms='RS256', 
audience=target_audience)

I also tried oauth2client, the code is here:

from oauth2client import crypt
import urllib.request, json
certificate_url = 'https://www.googleapis.com/robot/v1/metadata/x509/[email protected]'
target_audience = 'tried projectid/appid'
response = urllib.request.urlopen(certificate_url)
certs = response.read()
certs = json.loads(certs)
print(certs)
crypt.MAX_TOKEN_LIFETIME_SECS = 30 * 86400
idtoken = 'token received from await user.getIdToken()'
crypt.verify_signed_jwt_with_certs(idtoken, certs, target_audience)

I also tried firebase_admin for python:

import firebase_admin
from firebase_admin import credentials
from firebase_admin import auth
cred = credentials.Certificate('<firebase service accounts private key>')
default_app = firebase_admin.initialize_app(cred)
token = 'token from flutter'
verifyied =auth.verify_id_token(id_token=token)

Just to check whether the firebase_admin library itself is working or not, I passed the userid to server from the app and tried deleting the user using firebase_admin and I could do that. But for some reason I am unable to verify the token.

Thanks for the help.

alter123 alter123 · Accepted Answer · 2019-08-22T10:14:25

I have also faced the same issue.

Case:

Initially: I was printing auth token in vscode console and was verifying in terminal.

It gave me the error: token length cannot be 1 more than % 4.

I tried verifying the token from jwt.io and it was seemingly correct.

Actual Reason for the issue:

The console output of vscode (in my case windows 7 and 64 bit). Is limited to 1064 characters for a line.

Although the actual length of token is supposed to be 1170 characters.

Workaround Solution:

Print the substring in the vscode console and the join them in python shell to verify.

Unable to verify Firebase token

2 Answers