From c758c9547059d81940463c87be11a82a9fcf93ff Mon Sep 17 00:00:00 2001
From: Robin Krahl <robin@nitrokey.com>
Date: Tue, 5 Dec 2023 23:10:02 +0100
Subject: [PATCH] Fix field order in CredentialData

large_blob_key has to be added in the end so that index-based
deserialization still works for existing data.
---
 src/credential.rs | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/credential.rs b/src/credential.rs
index 9b17cdd..7612313 100644
--- a/src/credential.rs
+++ b/src/credential.rs
@@ -226,8 +226,6 @@ pub struct CredentialData {
     pub hmac_secret: Option<bool>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub cred_protect: Option<CredentialProtectionPolicy>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub large_blob_key: Option<Bytes<32>>,
     // TODO: add `sig_counter: Option<CounterId>`,
     // and grant RKs a per-credential sig-counter.
 
@@ -237,6 +235,10 @@ pub struct CredentialData {
     // used as a marker for new credentials.
     #[serde(skip_serializing_if = "Option::is_none")]
     use_short_id: Option<bool>,
+
+    // extensions (cont. -- we can only append new options due to index-based deserialization)
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub large_blob_key: Option<Bytes<32>>,
 }
 
 // TODO: figure out sizes
@@ -521,6 +523,7 @@ mod test {
             hmac_secret: Some(false),
             cred_protect: None,
             use_short_id: Some(true),
+            large_blob_key: Some(Bytes::from_slice(&[0xff; 32]).unwrap()),
         }
     }
 
@@ -599,6 +602,7 @@ mod test {
             hmac_secret: Some(false),
             cred_protect: None,
             use_short_id: Some(true),
+            large_blob_key: Some(random_bytes()),
         }
     }
 
@@ -680,6 +684,7 @@ mod test {
             nonce: Bytes::from_slice(&[u8::MAX; 12]).unwrap(),
             hmac_secret: Some(true),
             cred_protect: Some(CredentialProtectionPolicy::Required),
+            large_blob_key: Some(Bytes::from_slice(&[0xff; 32]).unwrap()),
         };
         trussed::virt::with_ram_client("fido", |mut client| {
             let kek = syscall!(client.generate_chacha8poly1305_key(Location::Internal)).key;
@@ -688,7 +693,7 @@ mod test {
                 .to_bytes()
                 .unwrap();
             let id = credential.id(&mut client, kek, &rp_id_hash).unwrap();
-            assert_eq!(id.0.len(), 204);
+            assert_eq!(id.0.len(), 239);
         });
     }