From eb3e2dd7a0103860b03ba8740fcf721ae7f4a17c Mon Sep 17 00:00:00 2001
From: Kevin Heifner <heifnerk@objectcomputing.com>
Date: Wed, 27 Mar 2024 09:47:04 -0500
Subject: [PATCH] GH-2286 Use const members, clean up construction

---
 .../include/fc/crypto/bls_public_key.hpp      |  9 ++--
 libraries/libfc/src/crypto/bls_public_key.cpp | 46 ++++++++++++-------
 2 files changed, 34 insertions(+), 21 deletions(-)

diff --git a/libraries/libfc/include/fc/crypto/bls_public_key.hpp b/libraries/libfc/include/fc/crypto/bls_public_key.hpp
index 63c3467a2a..f7e86b4717 100644
--- a/libraries/libfc/include/fc/crypto/bls_public_key.hpp
+++ b/libraries/libfc/include/fc/crypto/bls_public_key.hpp
@@ -22,8 +22,9 @@ namespace fc::crypto::blslib {
       bls_public_key() = default;
       bls_public_key(bls_public_key&&) = default;
       bls_public_key(const bls_public_key&) = default;
-      bls_public_key& operator=(const bls_public_key&) = default;
-      bls_public_key& operator=(bls_public_key&&) = default;
+
+      // Would prefer to not have this to enforce immutablity. Needed so keys can be copied around.
+      bls_public_key& operator=(const bls_public_key& rhs);
 
       // throws if unable to convert to valid bls12_381::g1
       explicit bls_public_key(std::span<const uint8_t, 96> affine_non_montgomery_le);
@@ -54,8 +55,8 @@ namespace fc::crypto::blslib {
       friend struct fc::has_reflector_init<bls_public_key>;
       void reflector_init();
 
-      std::array<uint8_t, 96> _affine_non_montgomery_le{};
-      bls12_381::g1           _jacobian_montgomery_le; // cached g1
+      const std::array<uint8_t, 96> _affine_non_montgomery_le{};
+      const bls12_381::g1           _jacobian_montgomery_le; // cached g1
    };
 
 }  // fc::crypto::blslib
diff --git a/libraries/libfc/src/crypto/bls_public_key.cpp b/libraries/libfc/src/crypto/bls_public_key.cpp
index 884ca5baa6..4baee03b36 100644
--- a/libraries/libfc/src/crypto/bls_public_key.cpp
+++ b/libraries/libfc/src/crypto/bls_public_key.cpp
@@ -5,33 +5,44 @@
 
 namespace fc::crypto::blslib {
 
-   bls_public_key::bls_public_key(std::span<const uint8_t, 96> affine_non_montgomery_le) {
-      std::ranges::copy(affine_non_montgomery_le, _affine_non_montgomery_le.begin());
-      constexpr bool check = true;  // verify
-      constexpr bool raw   = false; // to montgomery
-      auto           g1    = bls12_381::g1::fromAffineBytesLE(affine_non_montgomery_le, check, raw);
-      FC_ASSERT(g1, "Invalid bls_public_key");
-      _jacobian_montgomery_le = *g1;
-   }
-
-   static std::tuple<bls12_381::g1, std::array<uint8_t, 96>> pub_parse_base64url(const std::string& base64urlstr) {
+   inline std::array<uint8_t, 96> deserialize_base64url(const std::string& base64urlstr) {
       auto res = std::mismatch(config::bls_public_key_prefix.begin(), config::bls_public_key_prefix.end(),
                                base64urlstr.begin());
       FC_ASSERT(res.first == config::bls_public_key_prefix.end(), "BLS Public Key has invalid format : ${str}", ("str", base64urlstr));
 
       auto data_str = base64urlstr.substr(config::bls_public_key_prefix.size());
 
-      std::array<uint8_t, 96> bytes = fc::crypto::blslib::deserialize_base64url<std::array<uint8_t, 96>>(data_str);
-      
+      return fc::crypto::blslib::deserialize_base64url<std::array<uint8_t, 96>>(data_str);
+   }
+
+   inline bls12_381::g1 from_affine_bytes_le(const std::array<uint8_t, 96>& affine_non_montgomery_le) {
       constexpr bool check = true; // check if base64urlstr is invalid
       constexpr bool raw = false;  // non-montgomery
-      std::optional<bls12_381::g1> g1 = bls12_381::g1::fromAffineBytesLE(bytes, check, raw);
+      std::optional<bls12_381::g1> g1 = bls12_381::g1::fromAffineBytesLE(affine_non_montgomery_le, check, raw);
       FC_ASSERT(g1);
-      return {*g1, bytes};
+      return *g1;
+   }
+
+   inline std::array<uint8_t, 96> from_span(std::span<const uint8_t, 96> affine_non_montgomery_le) {
+      std::array<uint8_t, 96> r;
+      std::ranges::copy(affine_non_montgomery_le, r.begin());
+      return r;
+   }
+
+   bls_public_key::bls_public_key(std::span<const uint8_t, 96> affine_non_montgomery_le)
+      : _affine_non_montgomery_le(from_span(affine_non_montgomery_le))
+      , _jacobian_montgomery_le(from_affine_bytes_le(_affine_non_montgomery_le)) {
+   }
+
+   bls_public_key::bls_public_key(const std::string& base64urlstr)
+      : _affine_non_montgomery_le(deserialize_base64url(base64urlstr))
+      , _jacobian_montgomery_le(from_affine_bytes_le(_affine_non_montgomery_le)) {
    }
 
-   bls_public_key::bls_public_key(const std::string& base64urlstr) {
-      std::tie(_jacobian_montgomery_le, _affine_non_montgomery_le) = pub_parse_base64url(base64urlstr);
+   bls_public_key& bls_public_key::operator=(const bls_public_key& rhs) {
+      const_cast<std::array<uint8_t, 96>&>(_affine_non_montgomery_le) = rhs._affine_non_montgomery_le;
+      const_cast<bls12_381::g1&>(_jacobian_montgomery_le) = rhs._jacobian_montgomery_le;
+      return *this;
    }
 
    std::string bls_public_key::to_string() const {
@@ -45,7 +56,8 @@ namespace fc::crypto::blslib {
                     "FC unpack needs to call reflector_init otherwise unpacked_trx will not be initialized");
       std::optional<bls12_381::g1> g1 = bls12_381::g1::fromAffineBytesLE(_affine_non_montgomery_le);
       FC_ASSERT(g1, "Invalid bls public key ${k}", ("k", _affine_non_montgomery_le));
-      _jacobian_montgomery_le = *g1;
+      // reflector_init is private and only called during construction
+      const_cast<bls12_381::g1&>(_jacobian_montgomery_le) = *g1;
    }
 
 } // fc::crypto::blslib