Merge pull request #139 from str4d/135-better-mgmt-key-auth-error

Provide a better error message when management key authentication fails

i18n/en-US/age_plugin_yubikey.ftl

@@ -187,8 +187,12 @@ plugin-err-pin-required     = A PIN is required for {-yubikey} with serial {$yub
 
 ## Errors
 
+err-mgmt-key-auth = Failed to authenticate with the PIN-protected management key.
+rec-mgmt-key-auth =
+    Check whether your management key is using the TDES algorithm.
+    AES is not supported yet: {$aes_url}
 err-custom-mgmt-key = Custom unprotected non-TDES management keys are not supported.
-rec-custom-mgmt-key =
+rec-change-mgmt-key =
     You can use the {-yubikey} Manager CLI to change to a protected management key:
     {"  "}{$cmd}
 

src/error.rs

@@ -21,6 +21,7 @@ pub enum Error {
     InvalidSlot(u8),
     InvalidTouchPolicy(String),
     Io(io::Error),
+    ManagementKeyAuth,
     MultipleCommands,
     MultipleYubiKeys,
     NoEmptySlots(Serial),
@@ -50,12 +51,19 @@ impl From<yubikey::Error> for Error {
 // manually to provide the error output we want.
 impl fmt::Debug for Error {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        const CHANGE_MGMT_KEY_CMD: &str =
+            "ykman piv access change-management-key -a TDES --protect";
+        const CHANGE_MGMT_KEY_URL: &str = "https://developers.yubico.com/yubikey-manager/";
+
         match self {
             Error::CustomManagementKey => {
                 wlnfl!(f, "err-custom-mgmt-key")?;
-                let cmd = "ykman piv access change-management-key --protect";
+                wlnfl!(
-                let url = "https://developers.yubico.com/yubikey-manager/";
+                    f,
-                wlnfl!(f, "rec-custom-mgmt-key", cmd = cmd, url = url)?;
+                    "rec-change-mgmt-key",
+                    cmd = CHANGE_MGMT_KEY_CMD,
+                    url = CHANGE_MGMT_KEY_URL
+                )?;
             }
             Error::InvalidFlagCommand(flag, command) => wlnfl!(
                 f,
@@ -78,6 +86,17 @@ impl fmt::Debug for Error {
                 expected = "always, cached, never",
             )?,
             Error::Io(e) => wlnfl!(f, "err-io", err = e.to_string())?,
+            Error::ManagementKeyAuth => {
+                let aes_url = "https://github.com/str4d/age-plugin-yubikey/issues/92";
+                wlnfl!(f, "err-mgmt-key-auth")?;
+                wlnfl!(f, "rec-mgmt-key-auth", aes_url = aes_url)?;
+                wlnfl!(
+                    f,
+                    "rec-change-mgmt-key",
+                    cmd = CHANGE_MGMT_KEY_CMD,
+                    url = CHANGE_MGMT_KEY_URL
+                )?;
+            }
             Error::MultipleCommands => wlnfl!(f, "err-multiple-commands")?,
             Error::MultipleYubiKeys => wlnfl!(f, "err-multiple-yubikeys")?,
             Error::NoEmptySlots(serial) => {

src/key.rs

@@ -354,9 +354,13 @@ pub(crate) fn manage(yubikey: &mut YubiKey) -> Result<(), Error> {
         yubikey.change_pin(pin.as_bytes(), new_pin.as_bytes())?;
     }
 
-    if let Ok(mgm_key) = MgmKey::get_protected(yubikey) {
+    match MgmKey::get_protected(yubikey) {
-        yubikey.authenticate(mgm_key)?;
+        Ok(mgm_key) => yubikey.authenticate(mgm_key).map_err(|e| match e {
-    } else {
+            yubikey::Error::AuthenticationError => Error::ManagementKeyAuth,
+            _ => e.into(),
+        })?,
+        Err(yubikey::Error::AuthenticationError) => Err(Error::ManagementKeyAuth)?,
+        _ => {
             // Try to authenticate with the default management key.
             yubikey
                 .authenticate(MgmKey::default())
@@ -379,6 +383,7 @@ pub(crate) fn manage(yubikey: &mut YubiKey) -> Result<(), Error> {
             })?;
             eprintln!("{}", fl!("mgr-changing-mgmt-key-success"));
         }
+    }
 
     Ok(())
 }