Could not deserialize key data on decoding JWT python

Question

I am using pyjwt library for decoding the JWT token. I got this error when I am decoding. The code was given in the documantation.

import jwt

encoded_jwt=\'         


        

Answer 1

If you get this error double check your public key is exactly right, new lines are important.

key = '''-----BEGIN PUBLIC KEY-----
<main key here>
-----END PUBLIC KEY-----'''

Answer 2

MacOS Catalina 10.15.4 Python 2.7.16.

This solved the problem in my case

pip install cryptography==2.3

Answer 3

Use the authlib library, I never managed to decode keycloak tokens with pyjwt. You need a public_key, I assume you have it.

from authlib.jose import jwt
key = '-----BEGIN PUBLIC KEY-----\n' + public_key + '\n-----END PUBLIC KEY-----'
key_binary = key.encode('ascii')

try:
    claims = jwt.decode(encoded,key_binary)
    claims.validate()
    #do some logic here
    #...

ProTip: you may grab the public key easily from your auth server (in my case Keycloak) at some endpoint:

url = 'http://localhost:8080/auth/realms/your_realm'
with  urllib.request.urlopen(url) as r:
    response = r.read()
    public_key = json.loads(response)['public_key']

Answer 4

Its a good idea to use your RSA keys with OpenSSL:

openssl genrsa -out jwt-key 4096
openssl rsa -in jwt-key -pubout > jwt-key.pub

Reference: link

Answer 5

There are some issues in the pyjwt library. and you must get the public key from the certificate.

I used openssl x509 -pubkey -noout -in cert.pem > pubkey.pem

then from the public key I could easily decode it using authlib library.

from authlib.specs.rfc7519 import jwt

encoded_jwt='''eyJ0eXAiOiJ....'''
secret=b'''-----BEGIN PUBLIC KEY-----
......
-----END PUBLIC KEY-----'''
claims = jwt.decode(encoded_jwt, secret)
print(claims)

Answer 6

How did you encode your jwt? Use one of the approaches below

Encoding & Decoding Tokens with RS256 (RSA)

encoded = jwt.encode({'some': 'payload'}, private_key, algorithm='RS256')
decoded = jwt.decode(encoded, public_key, algorithms='RS256')

Reading the Claimset without Validation

jwt.decode(encoded, verify=False)
{u'some': u'payload'}

Or use same secret to encode and decode the jwt, one of the approach should work. In my case I used jwt.decode(token, verify=False) because my server has already did the signature validation for me, I only need to get the claimset.