Improve parsing of HSS-LMS parameters

GH #4440
randombit · Nov 21, 2024 · e33eb4a · e33eb4a
1 parent f91f829
commit e33eb4a
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Showing 2 changed files with 17 additions and 2 deletions.
diff --git a/src/lib/pubkey/hss_lms/hss.cpp b/src/lib/pubkey/hss_lms/hss.cpp
@@ -81,7 +81,15 @@ HSS_LMS_Params::HSS_LMS_Params(std::vector<LMS_LMOTS_Params_Pair> lm_lmots_param
 }
 
 HSS_LMS_Params::HSS_LMS_Params(std::string_view algo_params) {
-   SCAN_Name scan(fmt("HSS-LMS({})", algo_params));
+
+   const auto wrap_in_hss_lms = [&]() {
+      if(algo_params.starts_with("HSS-LMS(")) {
+         return std::string(algo_params);
+      } else {
+         return fmt("HSS-LMS({})", algo_params);
+      }
+   }();
+   SCAN_Name scan(wrap_in_hss_lms);
 
    BOTAN_ARG_CHECK(scan.arg_count() >= 2 && scan.arg_count() <= HSS_MAX_LEVELS + 1, "Invalid number of arguments");
    std::string hash = scan.arg(0);

diff --git a/src/lib/pubkey/pk_algs.cpp b/src/lib/pubkey/pk_algs.cpp
@@ -600,7 +600,14 @@ std::unique_ptr<Private_Key> create_private_key(std::string_view alg_name,
 
 #if defined(BOTAN_HAS_HSS_LMS)
    if(alg_name == "HSS-LMS") {
-      return std::make_unique<HSS_LMS_PrivateKey>(rng, params);
+      const auto hss_params = [&]() -> std::string {
+         if(params.empty()) {
+            return "SHA-256,HW(10,1)";
+         } else {
+            return std::string(params);
+         }
+      }();
+      return std::make_unique<HSS_LMS_PrivateKey>(rng, hss_params);
    }
 #endif