Identify non-standard received legacy enotes (#43)

---------

Co-authored-by: SNeedlewoods <sneedlewoods_1@protonmail.com>

src/ringct/rctTypes.h

@@ -53,6 +53,7 @@ extern "C" {
 #include "serialization/debug_archive.h"
 #include "serialization/binary_archive.h"
 #include "serialization/json_archive.h"
+#include "common/variant.h"
 
 
 //Define this flag when debugging to get additional info on the console
@@ -89,6 +90,7 @@ namespace rct {
     };
     typedef std::vector<key> keyV; //vector of keys
     typedef std::vector<keyV> keyM; //matrix of keys (indexed by column first)
+    using key_keyV_variant = tools::variant<key, keyV>;
 
     //containers For CT operations
     //if it's  representing a private ctkey then "dest" contains the secret key of the address

src/seraphis_core/legacy_core_utils.cpp

@@ -373,8 +373,8 @@ bool try_append_legacy_enote_ephemeral_pubkeys_to_tx_extra(const std::vector<rct
 }
 //-------------------------------------------------------------------------------------------------------------------
 void extract_legacy_enote_ephemeral_pubkeys_from_tx_extra(const TxExtra &tx_extra,
-    crypto::public_key &legacy_main_enote_ephemeral_pubkey_out,
-    std::vector<crypto::public_key> &legacy_additional_enote_ephemeral_pubkeys)
+    rct::key_keyV_variant &legacy_main_enote_ephemeral_pubkeys_out,
+    std::vector<crypto::public_key> &legacy_additional_enote_ephemeral_pubkeys_out)
 {
     // 1. parse field
     std::vector<cryptonote::tx_extra_field> tx_extra_fields;
@@ -385,17 +385,29 @@ void extract_legacy_enote_ephemeral_pubkeys_from_tx_extra(const TxExtra &tx_extr
     //       main enote ephemeral pubkey for key derivations
     cryptonote::tx_extra_pub_key pub_key_field;
 
-    if (cryptonote::find_tx_extra_field_by_type(tx_extra_fields, pub_key_field))
-        legacy_main_enote_ephemeral_pubkey_out = pub_key_field.pub_key;
-    else
-        legacy_main_enote_ephemeral_pubkey_out = rct::rct2pk(rct::I);
+    size_t pk_index = 0;
+    while (cryptonote::find_tx_extra_field_by_type(tx_extra_fields, pub_key_field, pk_index++))
+    {
+        if (pk_index == 1) // first iteration
+        {
+            legacy_main_enote_ephemeral_pubkeys_out = rct::pk2rct(pub_key_field.pub_key);
+            continue;
+        }
+        else if (pk_index == 2) // second iteration
+            legacy_main_enote_ephemeral_pubkeys_out = rct::keyV{legacy_main_enote_ephemeral_pubkeys_out.unwrap<rct::key>()};
+        legacy_main_enote_ephemeral_pubkeys_out.unwrap<rct::keyV>().push_back(rct::pk2rct(pub_key_field.pub_key));
+    }
+
+    if (legacy_main_enote_ephemeral_pubkeys_out.is_type<rct::key>() &&
+            legacy_main_enote_ephemeral_pubkeys_out.unwrap<rct::key>() == rct::key{})
+        legacy_main_enote_ephemeral_pubkeys_out = rct::I;
 
     // 3. try to get 'additional' enote ephemeral pubkeys (one per output): r_t K^v_t
     cryptonote::tx_extra_additional_pub_keys additional_pub_keys_field;
-    legacy_additional_enote_ephemeral_pubkeys.clear();
+    legacy_additional_enote_ephemeral_pubkeys_out.clear();
 
     if (cryptonote::find_tx_extra_field_by_type(tx_extra_fields, additional_pub_keys_field))
-        legacy_additional_enote_ephemeral_pubkeys = additional_pub_keys_field.data;
+        legacy_additional_enote_ephemeral_pubkeys_out = additional_pub_keys_field.data;
 }
 //-------------------------------------------------------------------------------------------------------------------
 } //namespace sp

src/seraphis_core/legacy_core_utils.h

@@ -274,12 +274,12 @@ bool try_append_legacy_enote_ephemeral_pubkeys_to_tx_extra(const std::vector<rct
 /**
 * brief: extract_legacy_enote_ephemeral_pubkeys_from_tx_extra - find legacy enote ephemeral pubkeys in a tx extra field
 * param: tx_extra - memo field (byte vector)
-* outparam: legacy_main_enote_ephemeral_pubkey_out - r G  (this should always be present, because yucky legacy tx gen code)
+* outparam: legacy_main_enote_ephemeral_pubkeys_out - r G  (this should always be present, because yucky legacy tx gen code)
 * outparam: legacy_additional_enote_ephemeral_pubkeys_out - [empty if no subaddress destinations]
 *                                                           [otherwise r_0 K^v_0, ..., r_n K^v_n]
 */
 void extract_legacy_enote_ephemeral_pubkeys_from_tx_extra(const TxExtra &tx_extra,
-    crypto::public_key &legacy_main_enote_ephemeral_pubkey_out,
+    rct::key_keyV_variant &legacy_main_enote_ephemeral_pubkeys_out,
     std::vector<crypto::public_key> &legacy_additional_enote_ephemeral_pubkeys_out);
 
 } //namespace sp

src/seraphis_main/scan_balance_recovery_utils.cpp

@@ -354,6 +354,30 @@ static std::unordered_set<rct::key> process_chunk_sp_selfsend_pass(
 }
 //-------------------------------------------------------------------------------------------------------------------
 //-------------------------------------------------------------------------------------------------------------------
+static rct::key& key_by_index_ref(rct::key_keyV_variant &variant, size_t index)
+{
+    struct visitor final : public tools::variant_static_visitor<rct::key&>
+    {
+        visitor(size_t index) : id{index} {}
+        size_t id;
+
+        using variant_static_visitor::operator();  //for blank overload
+        rct::key& operator()(rct::key &key_variant) const
+        {
+            CHECK_AND_ASSERT_THROW_MES(id == 0, "invalid index for rct::key.");
+            return key_variant;
+        }
+        rct::key& operator()(rct::keyV &key_variant) const
+        {
+            CHECK_AND_ASSERT_THROW_MES(id < key_variant.size(), "index greater than vector size.");
+            return key_variant[id];
+        }
+    };
+
+    return variant.visit(visitor{index});
+}
+//-------------------------------------------------------------------------------------------------------------------
+//-------------------------------------------------------------------------------------------------------------------
 bool try_find_legacy_enotes_in_tx(const rct::key &legacy_base_spend_pubkey,
     const std::unordered_map<rct::key, cryptonote::subaddress_index> &legacy_subaddress_map,
     const crypto::secret_key &legacy_view_privkey,
@@ -371,25 +395,22 @@ bool try_find_legacy_enotes_in_tx(const rct::key &legacy_base_spend_pubkey,
     basic_records_in_tx_out.clear();
 
     // 1. extract enote ephemeral pubkeys from the memo
-    crypto::public_key legacy_main_enote_ephemeral_pubkey;
+    rct::key_keyV_variant legacy_main_enote_ephemeral_pubkeys = rct::key{};
     std::vector<crypto::public_key> legacy_additional_enote_ephemeral_pubkeys;
 
     extract_legacy_enote_ephemeral_pubkeys_from_tx_extra(tx_memo,
-        legacy_main_enote_ephemeral_pubkey,
+        legacy_main_enote_ephemeral_pubkeys,
         legacy_additional_enote_ephemeral_pubkeys);
 
-    // 2. check if there are a valid number of additional enote ephemeral pubkeys
-    if (legacy_additional_enote_ephemeral_pubkeys.size() > 0 &&
-        legacy_additional_enote_ephemeral_pubkeys.size() != enotes_in_tx.size())
-        return false;
-
-    // 3. scan each enote in the tx using the 'additional enote ephemeral pubkeys'
+    // 2. scan each enote in the tx using the 'additional enote ephemeral pubkeys'
     // - this step is automatically skipped if legacy_additional_enote_ephemeral_pubkeys.size() == 0
     crypto::key_derivation temp_DH_derivation;
     LegacyContextualBasicEnoteRecordV1 temp_contextual_record{};
     bool found_an_enote{false};
 
-    for (std::size_t enote_index{0}; enote_index < legacy_additional_enote_ephemeral_pubkeys.size(); ++enote_index)
+    for (std::size_t enote_index{0}; enote_index < legacy_additional_enote_ephemeral_pubkeys.size() &&
+            enote_index < enotes_in_tx.size();
+            ++enote_index)
     {
         // a. compute the DH derivation for this enote ephemeral pubkey
         hwdev.generate_key_derivation(legacy_additional_enote_ephemeral_pubkeys[enote_index],
@@ -423,41 +444,67 @@ bool try_find_legacy_enotes_in_tx(const rct::key &legacy_base_spend_pubkey,
         found_an_enote = true;
     }
 
-    // 4. check if there is a main enote ephemeral pubkey
-    if (legacy_main_enote_ephemeral_pubkey == rct::rct2pk(rct::I))
+    // 3. check if there is a main enote ephemeral pubkey
+    if (legacy_main_enote_ephemeral_pubkeys.is_type<rct::key>() &&
+            legacy_main_enote_ephemeral_pubkeys.unwrap<rct::key>() == rct::I)
         return found_an_enote;
 
-    // 5. compute the key derivation for the main enote ephemeral pubkey
-    hwdev.generate_key_derivation(legacy_main_enote_ephemeral_pubkey, legacy_view_privkey, temp_DH_derivation);
+    // 4. compute the key derivations for all main enote ephemeral pubkeys
+    rct::key_keyV_variant temp_DH_derivations = rct::key{};
+    const auto pubkeys = legacy_main_enote_ephemeral_pubkeys.try_unwrap<rct::keyV>();
+    if (pubkeys)
+    {
+        rct::keyV temp{};
+        temp.reserve(pubkeys->size());
+        for (const rct::key &enote_ephemeral_pubkey : *pubkeys) {
+            hwdev.generate_key_derivation(rct::rct2pk(enote_ephemeral_pubkey), legacy_view_privkey, temp_DH_derivation);
+            temp.emplace_back((rct::key &) temp_DH_derivation);
+        }
+        temp_DH_derivations = temp;
+    }
+    else
+    {
+        hwdev.generate_key_derivation(rct::rct2pk(legacy_main_enote_ephemeral_pubkeys.unwrap<rct::key>()), legacy_view_privkey, temp_DH_derivation);
+        temp_DH_derivations = (rct::key &) temp_DH_derivation;
+    }
 
-    // 6. scan all enotes using the main key derivation
+    // 5. scan all enotes using key derivations for every ephemeral pub key
     for (std::size_t enote_index{0}; enote_index < enotes_in_tx.size(); ++enote_index)
     {
-        // a. try to recover a contextual basic record from the enote
-        if (!try_view_scan_legacy_enote_v1(legacy_base_spend_pubkey,
-                legacy_subaddress_map,
-                block_index,
-                block_timestamp,
-                transaction_id,
-                total_enotes_before_tx,
-                enote_index,
-                unlock_time,
-                tx_memo,
-                enotes_in_tx[enote_index],
-                legacy_main_enote_ephemeral_pubkey,
-                temp_DH_derivation,
-                origin_status,
-                hwdev,
-                temp_contextual_record))
-            continue;
+        // all ephemeral pub key - DH_derivation pairs
+        for (std::size_t pk_index{0};
+                (temp_DH_derivations.is_type<rct::keyV>() && pk_index < temp_DH_derivations.unwrap<rct::keyV>().size()) ||
+                (temp_DH_derivations.is_type<rct::key>() && pk_index < 1);
+                ++pk_index)
+        {
+            crypto::public_key temp_legacy_main_enote_ephemeral_pubkey = rct2pk(key_by_index_ref(legacy_main_enote_ephemeral_pubkeys, pk_index));
+            temp_DH_derivation = (crypto::key_derivation &) key_by_index_ref(temp_DH_derivations, pk_index);
+            // a. try to recover a contextual basic record from the enote
+            if (!try_view_scan_legacy_enote_v1(legacy_base_spend_pubkey,
+                    legacy_subaddress_map,
+                    block_index,
+                    block_timestamp,
+                    transaction_id,
+                    total_enotes_before_tx,
+                    enote_index,
+                    unlock_time,
+                    tx_memo,
+                    enotes_in_tx[enote_index],
+                    temp_legacy_main_enote_ephemeral_pubkey,
+                    temp_DH_derivation,
+                    origin_status,
+                    hwdev,
+                    temp_contextual_record))
+                continue;
 
-        // b. save the contextual basic record
-        // note: it is possible for enotes with duplicate onetime addresses to be added here; it is assumed the
-        //       upstream caller will be able to handle those without problems
-        basic_records_in_tx_out.emplace_back(temp_contextual_record);
+            // b. save the contextual basic record
+            // note: it is possible for enotes with duplicate onetime addresses to be added here; it is assumed the
+            //       upstream caller will be able to handle those without problems
+            basic_records_in_tx_out.emplace_back(temp_contextual_record);
 
-        // c. record that an owned enote has been found
-        found_an_enote = true;
+            // c. record that an owned enote has been found
+            found_an_enote = true;
+        }
     }
 
     return found_an_enote;