veyron/security: make loadPEMKey support nil encrypted passwords.
Backward compatibility for nil encrypted passwords from old loadPEMKey
function.
Change-Id: Ic0eb4fb082dea33cc1b408ce5b2233668f101da7
diff --git a/security/principal.go b/security/principal.go
index ab23b09..2b1f211 100644
--- a/security/principal.go
+++ b/security/principal.go
@@ -47,8 +47,7 @@
// LoadPersistentPrincipal reads state for a principal (private key, BlessingRoots, BlessingStore)
// from the provided directory 'dir' and commits all state changes to the same directory.
// If private key file does not exist then an error 'err' is returned such that os.IsNotExist(err) is true.
-// If private key file exists then 'passphrase' must be non-nil if the contents of the file are encrypted,
-// otherwise a MissingPassphraseErr is returned.
+// If private key file exists then 'passphrase' must be correct, otherwise PassphraseErr will be returned.
func LoadPersistentPrincipal(dir string, passphrase []byte) (security.Principal, error) {
key, err := loadKeyFromDir(dir, passphrase)
if err != nil {
