update godoc

crypto/keyring/doc.go

@@ -33,6 +33,8 @@
 //		https://github.com/KDE/kwallet
 //	pass	This backend uses the pass command line utility to store and retrieve keys:
 //		https://www.passwordstore.org/
+//	keyctl  This backend leverages the Linux's kernel security key management system
+//		to store cryptographic keys securely in memory. This is available on Linux only.
 //	test	This backend stores keys insecurely to disk. It does not prompt for a password to
 //		be unlocked and it should be used only for testing purposes.
 //	memory	Same instance as returned by NewInMemory. This backend uses a transient storage. Keys

crypto/keyring/keyring_linux.go

@@ -11,6 +11,7 @@ import (
 	"github.com/cosmos/cosmos-sdk/codec"
 )
 
+// Linux-only backend options.
 const BackendKeyctl = "keyctl"
 
 func newKeyctlBackendConfig(appName, _ string, _ io.Reader) keyring.Config {
@@ -24,7 +25,7 @@ func newKeyctlBackendConfig(appName, _ string, _ io.Reader) keyring.Config {
 
 // New creates a new instance of a keyring.
 // Keyring options can be applied when generating the new instance.
-// Available backends are "os", "file", "kwallet", "memory", "pass", "test".
+// Available backends are "os", "file", "kwallet", "memory", "pass", "test", "keyctl".
 func New(
 	appName, backend, rootDir string, userInput io.Reader, cdc codec.Codec, opts ...Option,
 ) (Keyring, error) {