WIP hss/def from_with_sst

Author: aewag

src/hss/definitions.rs

@@ -4,7 +4,7 @@ use tinyvec::ArrayVec;
 
 use crate::{
     constants::{
-        LmsTreeIdentifier, MAX_ALLOWED_HSS_LEVELS, MAX_HASH_SIZE, MAX_HSS_PUBLIC_KEY_LENGTH,
+        LmsTreeIdentifier, Node, MAX_ALLOWED_HSS_LEVELS, MAX_HSS_PUBLIC_KEY_LENGTH,
         MAX_SSTS_SIGNING_ENTITIES,
     },
     hasher::HashChain,
@@ -218,7 +218,7 @@ impl<H: HashChain> HssPublicKey<H> {
     pub fn from_with_sst(
         private_key: &ReferenceImplPrivateKey<H>,
         aux_data: Option<&mut &mut [u8]>,
-        intermed_nodes: &ArrayVec<[ArrayVec<[u8; MAX_HASH_SIZE]>; MAX_SSTS_SIGNING_ENTITIES]>,
+        intermed_nodes: &ArrayVec<[Node; MAX_SSTS_SIGNING_ENTITIES]>,
         tree_identifier: &LmsTreeIdentifier,
     ) -> Result<Self, ()> {
         let sst_extension = private_key.sst_option.as_ref().ok_or(())?;
@@ -229,27 +229,26 @@ impl<H: HashChain> HssPublicKey<H> {
         let top_lms_parameter = parameters[0].get_lms_parameter();
 
         let is_aux_data_used = aux_data.as_ref().map_or(false, |d| hss_is_aux_data_used(d));
-
         let mut opt_expanded_aux_data = HssPrivateKey::get_expanded_aux_data(
             aux_data,
             private_key,
             top_lms_parameter,
             is_aux_data_used,
         );
-        if opt_expanded_aux_data.as_mut().is_none() {
-            return Err(());
-        };
 
         let mut current_seed = private_key.generate_root_seed_and_lms_tree_identifier();
         current_seed
             .lms_tree_identifier
             .copy_from_slice(tree_identifier);
 
         // Move intermed_nodes, i.e. other subtree root nodes, into aux_data
+        (intermed_nodes.len() == 2usize.pow(sst_extension.l0_top_div().into()))
+            .then_some(())
+            .ok_or(())?;
         for (se_node, se_idx) in intermed_nodes.iter().zip(1..=intermed_nodes.len() as u8) {
             let si_sst_ext = SstExtension::new(se_idx, sst_extension.l0_top_div())?;
             let node_idx = get_sst_root_node_idx(top_lms_parameter, &si_sst_ext) as usize;
-            hss_save_aux_data::<H>(opt_expanded_aux_data.as_mut().unwrap(), node_idx, se_node);
+            hss_save_aux_data::<H>(opt_expanded_aux_data.as_mut().ok_or(())?, node_idx, se_node);
         }
 
         // Calculate public key with the help of the aux_data containing other subtree root nodes
@@ -263,7 +262,7 @@ impl<H: HashChain> HssPublicKey<H> {
 
         // Finalize aux_data by updating the HMAC
         hss_finalize_aux_data::<H>(
-            opt_expanded_aux_data.as_mut().unwrap(),
+            opt_expanded_aux_data.as_mut().ok_or(())?,
             private_key.seed.as_slice(),
         );