fixup! Reduce ID length for new credentials

src/credential.rs

@@ -233,8 +233,8 @@ pub struct CredentialData {
     // newer app versions, we strip unnecessary fields to generate a shorter credential ID.  To
     // make sure that the credential ID does not change for an existing credential, this field is
     // used as a marker for new credentials.
-    #[serde(default)]
-    use_short_id: bool,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    use_short_id: Option<bool>,
 }
 
 // TODO: figure out sizes
@@ -342,7 +342,7 @@ impl FullCredential {
             hmac_secret,
             cred_protect,
 
-            use_short_id: true,
+            use_short_id: Some(true),
         };
 
         FullCredential {
@@ -379,7 +379,7 @@ impl FullCredential {
                 .to_bytes()
                 .map_err(|_| Error::Other)?
         };
-        if self.use_short_id {
+        if self.use_short_id.unwrap_or_default() {
             StrippedCredential::from(self).id(trussed, key_encryption_key, &rp_id_hash)
         } else {
             let stripped_credential = self.strip();
@@ -509,7 +509,7 @@ mod test {
             key: Key::WrappedKey(Bytes::from_slice(&[1, 2, 3]).unwrap()),
             hmac_secret: Some(false),
             cred_protect: None,
-            use_short_id: true,
+            use_short_id: Some(true),
         }
     }
 
@@ -589,7 +589,7 @@ mod test {
             key: Key::WrappedKey(random_bytes()),
             hmac_secret: Some(false),
             cred_protect: None,
-            use_short_id: true,
+            use_short_id: Some(true),
         }
     }