It appears that ed25519 keys cannot be added to the key ring. When an attempt is made to add an ed25519 or ecdsa key, a message "Error reading response length from authentication socket." is given. The keyring accepts RSA keys, it should accept the other types of keys as well.
$ ssh-keygen -t rsa -P '' -f key_rsa
Generating public/private rsa key pair.
Your identification has been saved in key_rsa.
Your public key has been saved in key_rsa.pub.
The key fingerprint is:
bc:72:47:4e:34:5d:c1:f5:79:e8:7f:47:e9:dc:36:13 lars@gazelle9
The key's randomart image is:
+--[ RSA 2048]----+
| .oo.|
| . ...o|
| o . ..o|
| . . . . o|
| S o .E.|
| = ooo|
| . o o =*|
| o . .=|
| |
+-----------------+
$ ssh-keygen -t ed25519 -P '' -f key_ed25519
Generating public/private ed25519 key pair.
Your identification has been saved in key_ed25519.
Your public key has been saved in key_ed25519.pub.
The key fingerprint is:
f7:7e:7a:06:9b:f9:c7:c4:34:c5:73:d8:10:4a:ac:16 lars@gazelle9
The key's randomart image is:
+--[ED25519 256--+
| .. o* |
| E.....=|
| o. +|
| o ..|
| S.. o.|
| . .. o|
| .= o |
| .+ + o|
| o*.. |
+-----------------+
$ ssh-add key_rsa
Identity added: key_rsa (key_rsa)
$ ssh-add key_ed25519
Error reading response length from authentication socket.
Could not add identity: key_ed25519
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: gnome-keyring 3.10.1-1ubuntu4.1
ProcVersionSignature: Ubuntu 3.13.0-39.66-generic 3.13.11.8
Uname: Linux 3.13.0-39-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.5
Architecture: amd64
CurrentDesktop: Unity
Date: Mon Nov 17 21:32:02 2014
InstallationDate: Installed on 2014-10-26 (22 days ago)
InstallationMedia: Ubuntu 14.04.1 LTS "Trusty Tahr" - Release amd64 (20140722.2)
SourcePackage: gnome-keyring
UpgradeStatus: No upgrade log present (probably fresh install)
Appear to be a known issue in upstream gnome-keyring: https:/
Marking this report as a duplicate, as it from an Ubuntu point of view is currently being tracked in bug #771272.