ssh: RFC5208 support PKCS#8 key

Change-Id: I3d0ea816843c88930af3aa1f613978e0e90fa389
Reviewed-on: https://go-review.googlesource.com/127779
Reviewed-by: Han-Wen Nienhuys <hanwen@google.com>

ssh/keys.go

diff --git a/ssh/keys.go b/ssh/keys.go
index 73697de..34d9582 100644
--- a/ssh/keys.go
+++ b/ssh/keys.go
@@ -803,7 +803,7 @@
 }
 
 // ParseRawPrivateKey returns a private key from a PEM encoded private key. It
-// supports RSA (PKCS#1), DSA (OpenSSL), and ECDSA private keys.
+// supports RSA (PKCS#1), PKCS#8, DSA (OpenSSL), and ECDSA private keys.
 func ParseRawPrivateKey(pemBytes []byte) (interface{}, error) {
 	block, _ := pem.Decode(pemBytes)
 	if block == nil {
@@ -817,6 +817,9 @@
 	switch block.Type {
 	case "RSA PRIVATE KEY":
 		return x509.ParsePKCS1PrivateKey(block.Bytes)
+	// RFC5208 - https://tools.ietf.org/html/rfc5208
+	case "PRIVATE KEY":
+		return x509.ParsePKCS8PrivateKey(block.Bytes)
 	case "EC PRIVATE KEY":
 		return x509.ParseECPrivateKey(block.Bytes)
 	case "DSA PRIVATE KEY":

ssh/testdata/keys.go

diff --git a/ssh/testdata/keys.go b/ssh/testdata/keys.go
index 521b6be..bdaa9cb 100644
--- a/ssh/testdata/keys.go
+++ b/ssh/testdata/keys.go
@@ -61,6 +61,35 @@
 KCXFGd+SQ5GdUcEMe9isUH6DYj/6/yCDoFrXXmpQb+M=
 -----END RSA PRIVATE KEY-----
 `),
+	"pkcs8": []byte(`-----BEGIN PRIVATE KEY-----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+-----END PRIVATE KEY-----
+`),
 	"ed25519": []byte(`-----BEGIN OPENSSH PRIVATE KEY-----
 b3BlbnNzaC1rZXktdjEAAAAABG5vbmUAAAAEbm9uZQAAAAAAAAABAAAAMwAAAAtzc2gtZW
 QyNTUxOQAAACA+3f7hS7g5UWwXOGVTrMfhmxyrjqz7Sxxbx7I1j8DvvwAAAJhAFfkOQBX5