aes128gcm content encoding / MS Edge support

[ghys]

Hi,
I tested sending a notification to MS Edge - already working in Chrome and Firefox - without success: the push server (https://db5.notify.windows.com/w/?token=...) returns 400 Bad Request with no body.

After a quick check and according to https://github.com/web-push-libs/web-push-php/releases/tag/v4.0.0 it appears to be because it requires the aes128gcm content encoding, aesgcm won't work (I have not confirmed this).

Are there any plans to add support for aes128gcm? Thanks!

[martijndwars]

There were no plans, but I'd be happy to port this to the Java version once I find some time.

[ghys]

After some further investigation, I managed to make Edge receive notifications. The Microsoft push server does in fact support aesgcm,

I'll leave my troubleshooting steps here for reference:

• the 400 Bad Request was my fault (I had replaced Apache HTTP Client by JAX-RS and was sending headers wrong, but not wrong enough to make Chrome and Firefox fail ;)), after fixing this there was a 401 Unauthorized error. The detailed error description can actually be found in the push response's header (WWW-Authenticate: Bearer error="invalid_request",error_description="Malformed Crypto-Key Value")
• the trick was to remove the keyid=p256dh; part from the Encryption and Crypto-Key headers:
  

  webpush-java/src/main/java/nl/martijndwars/webpush/PushService.java

  Lines 171 to 172 in f5601e5

  	headers.put("Encryption", "keyid=p256dh;salt=" + base64url.omitPadding().encode(salt));
  	headers.put("Crypto-Key", "keyid=p256dh;dh=" + base64url.encode(dh));

Not sure if I should close this issue, supporting aes128gcm is still desirable since aesgcm will eventually be deprecated (see https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/SX9_nZ1NHy8). I'll leave it up to you :)

Thanks.

[martijndwars]

Let's leave the issue open, aes128gcm should be supported at some point.

the trick was to remove the keyid=p256dh; part from the Encryption and Crypto-Key headers:

Are you saying Edge supports aesgcm, but only when you remove keyid=p256dh;? This sounds like something that needs fixing as well..

The detailed error description can actually be found in the push response's header (WWW-Authenticate: Bearer error="invalid_request",error_description="Malformed Crypto-Key Value")

This is new to me, but sounds super useful. Thanks for sharing!

[ghys]

Are you saying Edge supports aesgcm, but only when you remove keyid=p256dh;?

Correct. I found out the notifications sent by the node library didn't include those and worked, and it was the only difference. I have also confirmed Google and Mozilla's servers are fine without it as well.

[fatjoem]

We noticed a sudden increase of this 401 Unauthorized error from microsoft endpoints yesterday. I assume that something changed that made the webpush feature available to a wider range of Edge users.

[fatjoem]

Is there any update on fixing this problem?

[martijndwars]

Not from my side, sorry. I haven't had time to look into this yet.

[fatjoem]

Is there a known downside to the fix described by @ghys ?

[oxc]

See web-push-libs/web-push#234 for removal from the Node.js library.

[maxpiepenbrink]

Thanks for this, I ran into this today and this Github link is what saved me. I wish we had a better explanation as to why microsoft's endpoint seems to care about this value.