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Fraunhofer-AISEC · Sep 6, 2024 · ffa2dac · ffa2dac
1 parent 03e957a
commit ffa2dac
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Showing 4 changed files with 26 additions and 46 deletions.
diff --git a/src/hss/definitions.rs b/src/hss/definitions.rs
@@ -184,9 +184,7 @@ 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, |data| hss_is_aux_data_used(data));
+        let is_aux_data_used = aux_data.as_ref().map_or(false, |d| hss_is_aux_data_used(d));
 
         let mut expanded_aux_data = HssPrivateKey::get_expanded_aux_data(
             aux_data,
@@ -230,9 +228,7 @@ 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, |data| hss_is_aux_data_used(data));
+        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,

diff --git a/src/hss/reference_impl_private_key.rs b/src/hss/reference_impl_private_key.rs
@@ -205,9 +205,7 @@ impl<H: HashChain> ReferenceImplPrivateKey<H> {
         hash_preimage[TOPSEED_WHICH] = 0x02;
         hasher.update(&hash_preimage);
 
-        // The root LmsTreeIdentifier needs to be the same for all signing entities for signing and verification
-        // TODO/Rework: maybe provide the LmsTreeIdentifier as an Option-argument for this function
-        //   instead of replacing it after calling the function
+        // Root LmsTreeIdentifier needs to be equal for all signing entities for sign & verify
         let lms_tree_identifier = hasher.finalize_reset()[..ILEN].try_into().unwrap();
 
         SeedAndLmsTreeIdentifier::new(&seed, &lms_tree_identifier)
@@ -416,7 +414,7 @@ mod tests {
             SIGNING_ENTITY_IDX as u8,
         );
         let impl_private_key = ReferenceImplPrivateKey::generate(
-            ssts_parameter.get_hss_parameters(),
+            ssts_parameter.hss_parameters(),
             &seed,
             Some(ssts_parameter.sst_extension().clone()),
         )

diff --git a/src/sst/gen_key.rs b/src/sst/gen_key.rs
@@ -1,6 +1,6 @@
 use crate::signature::Error;
 use crate::{
-    constants::{LmsTreeIdentifier, MAX_HASH_SIZE, MAX_SSTS_SIGNING_ENTITIES},
+    constants::{LmsTreeIdentifier, Node, MAX_HASH_SIZE, MAX_SSTS_SIGNING_ENTITIES},
     hasher::HashChain,
     hss::{
         aux::{hss_finalize_aux_data, hss_is_aux_data_used},
@@ -11,7 +11,7 @@ use crate::{
     },
     lms::definitions::LmsPrivateKey,
     lms::helper::get_tree_element,
-    sst::{helper, helper::get_sst_root_node_idx, parameters::SstsParameter},
+    sst::{helper::get_sst_root_node_idx, parameters::SstsParameter},
 };
 
 use tinyvec::ArrayVec;
@@ -21,38 +21,23 @@ pub fn prepare_sst_keygen<H: HashChain>(
     seed: &Seed<H>,
     aux_data: Option<&mut &mut [u8]>,
     tree_identifier: &mut LmsTreeIdentifier,
-) -> Result<(SigningKey<H>, ArrayVec<[u8; MAX_HASH_SIZE]>), Error> {
-    // create two representations of private keys because we need their data elements
-    // -> ReferenceImplPrivateKey and SigningKey
-    let rfc_private_key = ReferenceImplPrivateKey::generate(
-        sst_param.get_hss_parameters(),
-        seed,
-        Some(sst_param.sst_extension().clone()),
-    )
-    .map_err(|_| Error::new())?;
-
-    // get expanded AUX data
-    let is_aux_data_used = if let Some(ref aux_data) = aux_data {
-        hss_is_aux_data_used(aux_data)
-    } else {
-        false
-    };
+) -> Result<(SigningKey<H>, Node), Error> {
+    let hss_parameters = sst_param.hss_parameters();
+    let sst_extension = sst_param.sst_extension();
+
+    let rfc_private_key =
+        ReferenceImplPrivateKey::generate(hss_parameters, seed, Some(sst_extension.clone()))
+            .map_err(|_| Error::new())?;
+
+    let is_aux_data_used = aux_data.as_ref().map_or(false, |d| hss_is_aux_data_used(d));
 
     let mut expanded_aux_data = HssPrivateKey::get_expanded_aux_data(
         aux_data,
         &rfc_private_key,
-        sst_param.get_hss_parameters()[0].get_lms_parameter(),
+        hss_parameters[0].get_lms_parameter(),
         is_aux_data_used,
     );
 
-    // calculate our intermediate node hash value; for this we have to generate a LmsPrivateKey
-
-    // TODO/Review: better option? redundant (used leafs calculation)
-    let used_leafs_index = helper::get_sst_first_leaf_idx(
-        sst_param.get_hss_parameters()[0].get_lms_parameter(),
-        sst_param.sst_extension(),
-    );
-
     // Harmonising LMS tree identifier of root tree
     let mut seed_and_lms_tree_ident = rfc_private_key.generate_root_seed_and_lms_tree_identifier();
     if tree_identifier.iter().all(|&byte| byte == 0) {
@@ -63,19 +48,20 @@ pub fn prepare_sst_keygen<H: HashChain>(
             .clone_from_slice(tree_identifier);
     }
 
-    let our_node_index = get_sst_root_node_idx(
-        sst_param.get_hss_parameters()[0].get_lms_parameter(),
-        sst_param.sst_extension(),
-    );
+    let our_node_index =
+        get_sst_root_node_idx(hss_parameters[0].get_lms_parameter(), sst_extension);
 
     let lms_private_key = LmsPrivateKey::<H>::new(
         seed_and_lms_tree_ident.seed.clone(),
         seed_and_lms_tree_ident.lms_tree_identifier,
-        used_leafs_index, // actually not used in "get_tree_element", irrelevant
-        *sst_param.get_hss_parameters()[0].get_lmots_parameter(),
-        *sst_param.get_hss_parameters()[0].get_lms_parameter(),
-        Some(sst_param.sst_extension().clone()),
+        rfc_private_key
+            .compressed_used_leafs_indexes
+            .to(hss_parameters)[0],
+        *hss_parameters[0].get_lmots_parameter(),
+        *hss_parameters[0].get_lms_parameter(),
+        Some(sst_extension.clone()),
     );
+
     let our_intermed_node_value = get_tree_element(
         our_node_index as usize,
         &lms_private_key,

diff --git a/src/sst/parameters.rs b/src/sst/parameters.rs
@@ -21,7 +21,7 @@ impl<H: HashChain> SstsParameter<H> {
         }
     }
 
-    pub fn get_hss_parameters(
+    pub fn hss_parameters(
         &self,
     ) -> &ArrayVec<[HssParameter<H>; constants::REF_IMPL_MAX_ALLOWED_HSS_LEVELS]> {
         &self.hss_parameters