Error : Web push send from python backend to fire base using VAPI keys. Unhashable type:'slice'

[ishwara-bhat]

I have trouble getting pywebpush work for my python backend on gcp.

VAPI PUBLIC KEY and PVT KEY obtained from firebase dash board thourhg manual creation

#subscriptionObject comes from Angular front end. It used the VAPI PUBLIC KEY to receive the object.
I used the package versions specified in requirement.txt.
The call happens from a Flask app route.

webpush(subscription_info = subscriptionObject, data=notificationMessageObject, vapid_private_key=VAPID_PRIVATE_KEY, vapid_claims={"sub": "mailto:[email protected]"})
Error
Traceback (most recent call last): File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 2292, in wsgi_app response = self.full_dispatch_request() File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1815, in full_dispatch_request rv = self.handle_user_exception(e) File "/usr/local/lib/python3.7/site-packages/flask_cors/extension.py", line 110, in wrapped_function return cors_after_request(app.make_response(f(*args, **kwargs))) File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1718, in handle_user_exception reraise(exc_type, exc_value, tb) File "/usr/local/lib/python3.7/site-packages/flask/_compat.py", line 35, in reraise raise value File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1813, in full_dispatch_request rv = self.dispatch_request() File "/usr/local/lib/python3.7/site-packages/flask/app.py", line 1799, in dispatch_request return self.view_functionsrule.endpoint File "/app/main.py", line 428, in notify_one_device webpush(subscription_info = subsObject, data=notificationMessageObject, vapid_private_key=VAPID_PRIVATE_KEY, vapid_claims={"sub": "mailto:[email protected]"}) File "/usr/local/lib/python3.7/site-packages/pywebpush/init.py", line 485, in webpush timeout=timeout, File "/usr/local/lib/python3.7/site-packages/pywebpush/init.py", line 305, in send encoded = self.encode(data, content_encoding) File "/usr/local/lib/python3.7/site-packages/pywebpush/init.py", line 219, in encode version=content_encoding) File "/usr/local/lib/python3.7/site-packages/http_ece/init.py", line 394, in encrypt content[i:i + chunk_size], TypeError: unhashable type: 'slice'

Please guide how I should approach this.

[cmesas]

@ishwara-bhat I have the same problem, how could you solve it?

[jrconlin]

Reading the dump, it appears that the problem is that http_ece can't encrypt content.
content comes from data in self.encode(data, content_encoding)

from a very quick view, I'm going to guess that the data being passed in is not a byte array. You may need to serialize the object content into a string or byte array before passing it to webpush.encode

[ishwara-bhat]

For web push alone, I went for nodejs service. Rest of my back end is in python.

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[cmesas]

Reading the dump, it appears that the problem is that http_ece can't encrypt content. content comes from data in self.encode(data, content_encoding)

from a very quick view, I'm going to guess that the data being passed in is not a byte array. You may need to serialize the object content into a string or byte array before passing it to webpush.encode

An example of a key pair that I am using are the following. I am using string strings directly.

{
"subject": "mailto: [email protected]",
"publicKey": "BLR4PgElXtaeu16JlFEfVuOZkyub-Y36w1XRDYvl7-gNOKUpW-YadhR0Yv6vnrz5h4HhJG5jq0arBRuIrJdWXtQ",
"privateKey": "LqUduWL7V0F7pOrYep5oTgZJaCXLl7eRvMZMpAE6DCA"
}

Is it necessary to use PEM certificates or can I use string keys?

[jrconlin]

String keys can be in either raw or DER format: https://github.com/web-push-libs/vapid/blob/main/python/py_vapid/__init__.py#L134-L147. If you provide a path, py_vapid will try to read the file as either PEM or DER formatted https://github.com/web-push-libs/vapid/blob/main/python/py_vapid/__init__.py#L134-L147

[cmesas]

Las claves de cadena pueden estar en formato raw o DER: https://github.com/web-push-libs/vapid/blob/main/python/py_vapid/__init__.py#L134-L147 . Si proporciona una ruta, py_vapid intentará leer el archivo con formato PEM o DER https://github.com/web-push-libs/vapid/blob/main/python/py_vapid/__init__.py#L134-L147

Ok, I will try to work with the private key in PEM format from the file directly.

[treygilliland]

Just ran into this same issue. Make sure your data payload is JSON string encoded and not just a raw python dictionary.