Error : Web push send from python backend

[Carlos Mesas]

Hello, I'm having a problem when I try to run a notification, I think I'm following the documentation to the letter.

Information

Keys generated with vpaid (python): https://github.com/web-push-libs/vapid/tree/main/python

• The keys that I indicate are for testing...

PrivateKey [private_key.pem]
----BEGIN PRIVATE KEY-----
MIGHAgEAMBMGByqGSM49AgEGCCqGSM49AwEHBG0wawIBAQQg4zLDHdp8DtxtcAO4
MZVGeyp2JLJyVrqaMII75nGeAC+hRANCAATW1506jo86/0Ek72wj/AYgGZ6d1R3i
wabGfNb7DlMSmIrdYbrgLLI6HgnszgCGM1ORilZ95RoW9x0ER8+h8SI2
-----END PRIVATE KEY-----

ApplicationServerKey:
BNbXnTqOjzr_QSTvbCP8BiAZnp3VHeLBpsZ81vsOUxKYit1huuAssjoeCezOAIYzU5GKVn3lGhb3HQRHz6HxIjY

Subscription (chrome client: successfully generated with the ApplicationServerKey):
{"endpoint":"https://fcm.googleapis.com/fcm/send/eN9gFAJxIeA:APA91bGRifdlYB8pDgJ9wEYNxxIrVkT5Lb2cNTvtiU55-0bFmV4KGVBuIYbk67NRPjflK4FFdA5tJBPtHVaMMV0IzLrDvBtpBy1cd5VDzrKjXbBN5rJ5NWF-RurzHaFX2iBiun_ypzCT","expirationTime":null,"keys":{"p256dh":"BD9sOH3XIEbgk1x_KvtLbCLvyYEnuQ972W4LaTUnvl_-7vB_q8IzToFKGWK_QaTtUhWBj-Tb556xPuR9uXmr6-E","auth":"X0Zy2i_2WC3tkjElaK3D2g"}}

Code
webpush(
vapid_private_key="private_key.pem",
vapid_claims={"sub": "mailto:[e-mail]"},
subscription_info=subscription,
data=data
)

Error
...
return base64.urlsafe_b64decode(data + b"===="[len(data) % 4:])
File "/usr/lib/python3.8/base64.py", line 133, in urlsafe_b64decode
return b64decode(s)
File "/usr/lib/python3.8/base64.py", line 87, in b64decode
return binascii.a2b_base64(s)
binascii.Error: Incorrect padding

@jrconlin Could you tell me what I may be doing wrong?

[Carlos Mesas]

@jrconlin any ideas what I may be doing wrong? I am blocked and the only solution I would have would be to integrate in node that I have seen that I have no problem.

[JR Conlin]

Hrm,

On my system, your private key is invalid. If that was generated by vapid, I'm not sure why it made an invalid key, but you can also create one by using openssl directly:

openssl ecparam -genkey -name prime256v1 -noout -out private_key.pem

I'm also not sure why you're seeing the incorrect padding error. I tried the application string and it worked fine.

[Carlos Mesas]

Hrm,

On my system, your private key is invalid. If that was generated by vapid, I'm not sure why it made an invalid key, but you can also create one by using openssl directly:

openssl ecparam -genkey -name prime256v1 -noout -out private_key.pem

I'm also not sure why you're seeing the incorrect padding error. I tried the application string and it worked fine.

Thanks, I'll try again as you say.

[Carlos Mesas]

Hrm,
On my system, your private key is invalid. If that was generated by vapid, I'm not sure why it made an invalid key, but you can also create one by using openssl directly:
openssl ecparam -genkey -name prime256v1 -noout -out private_key.pem
I'm also not sure why you're seeing the incorrect padding error. I tried the application string and it worked fine.

Thanks, I'll try again as you say.

Thanks, finally without generating the keys through the vapid library I got it to work.

I found these commands that I think could be useful for people who want to work with DER (bas64), I'll leave it here:

openssl ecparam -genkey -name prime256v1 -noout -out private_key.pem
openssl ec -in private_key.pem -pubout -outform DER|tail -c 65|base64|tr -d '=' |tr '/+' '-' >> public.key
openssl ec -in private_key.pem -outform DER|tail -c +8|head -c 32|base64|tr -d '=' |tr '/+' '-' >> private. key

Thank @jrconlin