UserAgent: Mozilla/5.0 (X11; CrOS x86_64 11210.0.0) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3593.0 Safari/537.36
Platform: 11210.0.0 (Official Build) dev-channel cave

Steps to reproduce the problem:
1. Load a ed25519 key on the authentication slot of a smartcard (Nitrokey Start)
2. Start Secure Shell App with --ssh-agent=gsc under ssh relay options and allow said app in Smart Card Connector app

What is the expected behavior?
Authenticate successfully on remote ssh host.

What went wrong?
After doing some debugging, I see that in the nassh.agent.backends.GSC.SmartCardManager.prototype.fetchPublicKeyBlob() method, the publicKeyTemplate takes the following value:

nassh.agent.backends.GSC.DataObject {tagClass: 1, tagClassDescription: "application", isConstructed: true, tagNumber: 73, tag: 18815, …}
children: Array(1)
0: nassh.agent.backends.GSC.DataObject
isConstructed: false
tag: 134
tagClass: 2
tagClassDescription: "context-specific"
tagDescription: "<unimplemented tag: 134>"
tagNumber: 6
value: Uint8Array(32) [xxx]
valueLength: 32
__proto__: Object
length: 1
__proto__: Array(0)
isConstructed: true
tag: 18815
tagClass: 1
tagClassDescription: "application"
tagDescription: "<unimplemented tag: 18815>"
tagNumber: 73
valueLength: 34
__proto__: Object

Background: I am on Chrome OS, and trying out the Secure Shell app together with the Smart Card Connector app with a Nitrokey Start. The key on the authentication slot is a ed25519 one, which was saved to the card after executing

$ gpg-connect-agent "SCD SETATTR KEY-ATTR --force 3 22 ed25519" /bye

per [1].

I am able to authenticate properly on a regular desktop with gpg --enable-ssh-support. However on Chrome OS, I followed the instructions on [2] with `--ssh-agent=gsc`, and even with -vvv in ssh options, could not figure out why my (public) key was not being advertised by Secure Shell.

WebStore page: Secure Shell App

Did this work before? N/A 

Chrome version: 72.0.3593.0  Channel: n/a
OS Version: 11210.0.0
Flash Version: