WIP: allow for two binary formats

Fraunhofer-AISEC · Sep 2, 2024 · 76dff01 · 76dff01
1 parent 0480313
commit 76dff01
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Showing 3 changed files with 19 additions and 10 deletions.
diff --git a/src/hss/mod.rs b/src/hss/mod.rs
@@ -380,8 +380,7 @@ mod tests {
 
         for index in 0..keypair_lifetime {
             assert_eq!(
-                signing_key.as_slice()[REF_IMPL_SSTS_EXT_SIZE
-                    ..HSS_COMPRESSED_USED_LEAFS_SIZE + REF_IMPL_SSTS_EXT_SIZE],
+                signing_key.as_slice()[..HSS_COMPRESSED_USED_LEAFS_SIZE],
                 index.to_be_bytes(),
             );
             assert_eq!(
@@ -410,7 +409,9 @@ mod tests {
             );
         }
         assert_eq!(
-            signing_key.as_slice()[(REF_IMPL_MAX_PRIVATE_KEY_SIZE - H::OUTPUT_SIZE as usize)..],
+            signing_key.as_slice()[(REF_IMPL_MAX_PRIVATE_KEY_SIZE
+                - REF_IMPL_SSTS_EXT_SIZE
+                - H::OUTPUT_SIZE as usize)..],
             [0u8; H::OUTPUT_SIZE as usize],
         );
     }

diff --git a/src/hss/reference_impl_private_key.rs b/src/hss/reference_impl_private_key.rs
@@ -133,8 +133,10 @@ impl<H: HashChain> ReferenceImplPrivateKey<H> {
     pub fn to_binary_representation(&self) -> ArrayVec<[u8; REF_IMPL_MAX_PRIVATE_KEY_SIZE]> {
         let mut result = ArrayVec::new();
 
-        result.extend_from_slice(&self.sst_ext.signing_entity_idx.to_be_bytes());
-        result.extend_from_slice(&self.sst_ext.l0_top_div.to_be_bytes());
+        if self.sst_ext != SstExtension::default() {
+            result.extend_from_slice(&self.sst_ext.signing_entity_idx.to_be_bytes());
+            result.extend_from_slice(&self.sst_ext.l0_top_div.to_be_bytes());
+        }
         result.extend_from_slice(&self.compressed_used_leafs_indexes.count.to_be_bytes());
         result.extend_from_slice(&self.compressed_parameter.0);
         result.extend_from_slice(self.seed.as_slice());
@@ -143,16 +145,22 @@ impl<H: HashChain> ReferenceImplPrivateKey<H> {
     }
 
     pub fn from_binary_representation(data: &[u8]) -> Result<Self, ()> {
-        if data.len() != REF_IMPL_MAX_PRIVATE_KEY_SIZE - MAX_SEED_LEN + H::OUTPUT_SIZE as usize {
+        if data.len() != REF_IMPL_MAX_PRIVATE_KEY_SIZE - MAX_SEED_LEN + H::OUTPUT_SIZE as usize
+            && data.len()
+                != REF_IMPL_MAX_PRIVATE_KEY_SIZE - MAX_SEED_LEN + H::OUTPUT_SIZE as usize
+                    - REF_IMPL_SSTS_EXT_SIZE
+        {
             // TODO/Review: why don't we just use REF_IMPL_MAX_PRIVATE_KEY_SIZE? (as in "SigningKey")?
             return Err(());
         }
 
         let mut result = Self::default();
         let mut index = 0;
 
-        let ssts_ext = read_and_advance(data, REF_IMPL_SSTS_EXT_SIZE, &mut index);
-        result.sst_ext = SstExtension::from_slice(ssts_ext)?;
+        if data.len() == REF_IMPL_MAX_PRIVATE_KEY_SIZE - MAX_SEED_LEN + H::OUTPUT_SIZE as usize {
+            let ssts_ext = read_and_advance(data, REF_IMPL_SSTS_EXT_SIZE, &mut index);
+            result.sst_ext = SstExtension::from_slice(ssts_ext)?;
+        }
 
         let compressed_used_leafs_indexes =
             read_and_advance(data, HSS_COMPRESSED_USED_LEAFS_SIZE, &mut index);

diff --git a/tests/reference_implementation.rs b/tests/reference_implementation.rs
@@ -126,8 +126,8 @@ fn should_produce_same_private_key() {
     let ref_signing_key = read_private_key(path);
     let ref_verifying_key = read_public_key(path);
 
-    assert!(ref_signing_key == sk.as_slice());
-    assert!(ref_verifying_key == vk.as_slice());
+    assert_eq!(ref_signing_key, sk.as_slice());
+    assert_eq!(ref_verifying_key, vk.as_slice());
 }
 
 fn read_private_key(path: &Path) -> Vec<u8> {