diff --git a/src/register.rs b/src/register.rs
index c6dd248..6fdac3e 100644
--- a/src/register.rs
+++ b/src/register.rs
@@ -71,6 +71,8 @@ impl Command for CommandImpl {
                     println!("{}", serde_json::to_string_pretty(&data).unwrap());
                 } else {
                     success!("Device info: {}", data.device_info);
+                    success!("Register challenge: {}", u2fv2_challenge_str);
+                    success!("Register challenge base64: {}", base64::encode(&u2fv2_challenge_str));
                     if let Some(cert) = data.attestation_cert_pem {
                         success!("Certificate: {}", cert);
                     }
diff --git a/src/sign.rs b/src/sign.rs
index 827af3f..0f43d15 100644
--- a/src/sign.rs
+++ b/src/sign.rs
@@ -77,6 +77,8 @@ impl Command for CommandImpl {
         let (_, handle_used, sign_data, device_info) = sign_result.expect("Sign failed");
 
         success!("Device info: {}", &device_info);
+        success!("Sign challenge: {}", u2fv2_challenge_str);
+        success!("Sign challenge base64: {}", base64::encode(&u2fv2_challenge_str));
         success!("Sign result: {}", base64::encode(&sign_data));
         success!("Key handle used: {}", base64::encode(&handle_used));
         success!("Key handle used: {}", hex::encode(&handle_used));