HostKeyFile Not support ED25519

[fcharlie]

When I use ssh.HostKeyFile add a /etc/ssh/ssh_host_ed25519_key, Start ssh server error, Report: unsupported key type 'OPENSSH PRIVATE KEY'

In fact, when i use ssh.ParsePrivateKey(x/crypto/ssh), it can support ed25519

func AddHostKeyFile(filepath string, srv *ssh.Server) {
	pemBytes, err := ioutil.ReadFile(filepath)
	if err != nil {
		log.Printf("AddHostKeyFile: %s", err)
		return
	}
	hostKey, err := gossh.ParsePrivateKey(pemBytes)
	if err != nil {
		log.Printf("Fatal to parse host key: %s, %s", filepath, err)
		return
	}
	srv.AddHostKey(hostKey)
	return
}

Bug in:

ssh/util.go

Line 14 in 4a4de39

func signerFromBlock(block *pem.Block) (ssh.Signer, error) {

func signerFromBlock(block *pem.Block) (ssh.Signer, error) {
	var key interface{}
	var err error
	switch block.Type {
	case "RSA PRIVATE KEY":
		key, err = x509.ParsePKCS1PrivateKey(block.Bytes)
	case "EC PRIVATE KEY":
		key, err = x509.ParseECPrivateKey(block.Bytes)
	case "DSA PRIVATE KEY":
		key, err = ssh.ParseDSAPrivateKey(block.Bytes)
	default:// NOT parse ed25519
		return nil, fmt.Errorf("unsupported key type %q", block.Type)
	}
	if err != nil {
		return nil, err
	}
	signer, err := ssh.NewSignerFromKey(key)
	if err != nil {
		return nil, err
	}
	return signer, nil
}

[progrium]

Yep, easy fix is to use ssh.ParsePrivateKey from x/crypto/ssh. I don't believe it existed at the time. Would love a PR.

[belak]

It looks like signerFromBlock is pretty close to a direct copy from ParseRawPrivateKey. The main downside to ssh.ParsePrivateKey is that it only supports a single private key block, while the code here supports adding multiple keys from a single file.

[progrium]

I don't think it's very common for an SSH key to have more than key in a file, right? I'd love to optimize for less code to maintain here.

[belak]

Not that I'm aware of. It would be a trivial fix to rip out the custom code and move to gossh.ParsePrivateKey as long as we're aware it would break this specific case.

[progrium]

I'm down, now is the time to break stuff pre-1.0 still.

[progrium]

@fcharlie can you pull master and let us know if this is still an issue?

[fcharlie]

OK, it work !