This library contains some basic tools for working with elliptic curve SSH keys.
Private keys's can be created using PHPECC, and serialized using it's DER/PEM private key serializer. There is also the EncryptedPrivateKeySerializer, used to create older SSH formatted keys. PKCS#8 encoding is on the wishlist.
There is also an SshPublicKeySerializer, which encodes the curve/public key in the SSH format. This is the encoding used for authentication (authorized_keys, Github, etc).