1 files changed, 13 insertions, 2 deletions
diff --git a/nitrocli/src/commands.rs b/nitrocli/src/commands.rs
index eac8549..a65f070 100644
--- a/nitrocli/src/commands.rs
+++ b/nitrocli/src/commands.rs
@@ -646,7 +646,7 @@ fn prepare_base32_secret(secret: &str) -> Result<String> {
 /// Configure a one-time password slot on the Nitrokey device.
 pub fn otp_set(
   ctx: &mut args::ExecCtx<'_>,
-  data: nitrokey::OtpSlotData,
+  mut data: nitrokey::OtpSlotData,
   algorithm: args::OtpAlgorithm,
   counter: u64,
   time_window: u16,
@@ -656,7 +656,18 @@ pub fn otp_set(
     let secret = match secret_format {
       args::OtpSecretFormat::Ascii => prepare_ascii_secret(&data.secret)?,
       args::OtpSecretFormat::Base32 => prepare_base32_secret(&data.secret)?,
-      args::OtpSecretFormat::Hex => data.secret,
+      args::OtpSecretFormat::Hex => {
+        // We need to ensure to provide a string with an even number of
+        // characters in it, just because that's what libnitrokey
+        // expects. So prepend a '0' if that is not the case.
+        // TODO: This code can be removed once upstream issue #164
+        //       (https://github.com/Nitrokey/libnitrokey/issues/164) is
+        //       addressed.
+        if data.secret.len() % 2 != 0 {
+          data.secret.insert(0, '0')
+        }
+        data.secret
+      }
     };
     let data = nitrokey::OtpSlotData { secret, ..data };
     let device = authenticate_admin(ctx, device)?;