From f2c4c39971f25adaecde377ad325856ea785b9ac Mon Sep 17 00:00:00 2001
From: moneromooo-monero <moneromooo-monero@users.noreply.github.com>
Date: Sat, 10 Feb 2018 10:38:33 +0000
Subject: wallet2: speed up subaddress generation (by about a third)

---
 src/cryptonote_basic/cryptonote_format_utils.cpp | 39 ++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

(limited to 'src/cryptonote_basic/cryptonote_format_utils.cpp')

diff --git a/src/cryptonote_basic/cryptonote_format_utils.cpp b/src/cryptonote_basic/cryptonote_format_utils.cpp
index aab4f380c..c668ceae5 100644
--- a/src/cryptonote_basic/cryptonote_format_utils.cpp
+++ b/src/cryptonote_basic/cryptonote_format_utils.cpp
@@ -172,6 +172,45 @@ namespace cryptonote
     return m;
   }
   //---------------------------------------------------------------
+  std::vector<crypto::public_key> get_subaddress_spend_public_keys(const cryptonote::account_keys &keys, uint32_t account, uint32_t begin, uint32_t end)
+  {
+    CHECK_AND_ASSERT_THROW_MES(begin <= end, "begin > end");
+
+    std::vector<crypto::public_key> pkeys;
+    pkeys.reserve(end - begin);
+    cryptonote::subaddress_index index = {account, begin};
+
+    ge_p3 p3;
+    ge_cached cached;
+    CHECK_AND_ASSERT_THROW_MES(ge_frombytes_vartime(&p3, (const unsigned char*)keys.m_account_address.m_spend_public_key.data) == 0,
+        "ge_frombytes_vartime failed to convert spend public key");
+    ge_p3_to_cached(&cached, &p3);
+
+    for (uint32_t idx = begin; idx < end; ++idx)
+    {
+      index.minor = idx;
+      if (index.is_zero())
+      {
+        pkeys.push_back(keys.m_account_address.m_spend_public_key);
+        continue;
+      }
+      const crypto::secret_key m = cryptonote::get_subaddress_secret_key(keys.m_view_secret_key, index);
+
+      // M = m*G
+      ge_scalarmult_base(&p3, (const unsigned char*)m.data);
+
+      // D = B + M
+      crypto::public_key D;
+      ge_p1p1 p1p1;
+      ge_add(&p1p1, &p3, &cached);
+      ge_p1p1_to_p3(&p3, &p1p1);
+      ge_p3_tobytes((unsigned char*)D.data, &p3);
+
+      pkeys.push_back(D);
+    }
+    return pkeys;
+  }
+  //---------------------------------------------------------------
   bool generate_key_image_helper(const account_keys& ack, const std::unordered_map<crypto::public_key, subaddress_index>& subaddresses, const crypto::public_key& out_key, const crypto::public_key& tx_public_key, const std::vector<crypto::public_key>& additional_tx_public_keys, size_t real_output_index, keypair& in_ephemeral, crypto::key_image& ki)
   {
     crypto::key_derivation recv_derivation = AUTO_VAL_INIT(recv_derivation);
-- 
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