From 09e25071f40c564af08a1386c39c4f2d8eb484b6 Mon Sep 17 00:00:00 2001 From: Andrew Chow Date: Fri, 28 Feb 2020 16:55:24 -0500 Subject: Cache parent xpub inside of BIP32PubkeyProvider Optimize Expand by having BIP32PubkeyProvider also cache the parent (or only) xpub within itself. Since Expand does not provide a read cache, it is useful to internally cache this xpub to avoid re-deriving the same xpub. --- src/script/descriptor.cpp | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) (limited to 'src/script') diff --git a/src/script/descriptor.cpp b/src/script/descriptor.cpp index 588e583339..83dc046ca1 100644 --- a/src/script/descriptor.cpp +++ b/src/script/descriptor.cpp @@ -165,7 +165,7 @@ public: * write_cache is the cache to write keys to (if not nullptr) * Caches are not exclusive but this is not tested. Currently we use them exclusively */ - virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) const = 0; + virtual bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) = 0; /** Whether this represent multiple public keys at different positions. */ virtual bool IsRange() const = 0; @@ -195,7 +195,7 @@ class OriginPubkeyProvider final : public PubkeyProvider public: OriginPubkeyProvider(uint32_t exp_index, KeyOriginInfo info, std::unique_ptr provider) : PubkeyProvider(exp_index), m_origin(std::move(info)), m_provider(std::move(provider)) {} - bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) const override + bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) override { if (!m_provider->GetPubKey(pos, arg, key, info, read_cache, write_cache)) return false; std::copy(std::begin(m_origin.fingerprint), std::end(m_origin.fingerprint), info.fingerprint); @@ -225,7 +225,7 @@ class ConstPubkeyProvider final : public PubkeyProvider public: ConstPubkeyProvider(uint32_t exp_index, const CPubKey& pubkey) : PubkeyProvider(exp_index), m_pubkey(pubkey) {} - bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) const override + bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key, KeyOriginInfo& info, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) override { key = m_pubkey; info.path.clear(); @@ -262,6 +262,9 @@ class BIP32PubkeyProvider final : public PubkeyProvider CExtPubKey m_root_extkey; KeyPath m_path; DeriveType m_derive; + // Cache of the parent of the final derived pubkeys. + // Primarily useful for situations when no read_cache is provided + CExtPubKey m_cached_xpub; bool GetExtKey(const SigningProvider& arg, CExtKey& ret) const { @@ -298,7 +301,7 @@ public: BIP32PubkeyProvider(uint32_t exp_index, const CExtPubKey& extkey, KeyPath path, DeriveType derive) : PubkeyProvider(exp_index), m_root_extkey(extkey), m_path(std::move(path)), m_derive(derive) {} bool IsRange() const override { return m_derive != DeriveType::NO; } size_t GetSize() const override { return 33; } - bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key_out, KeyOriginInfo& final_info_out, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) const override + bool GetPubKey(int pos, const SigningProvider& arg, CPubKey& key_out, KeyOriginInfo& final_info_out, const DescriptorCache* read_cache = nullptr, DescriptorCache* write_cache = nullptr) override { // Info of parent of the to be derived pubkey KeyOriginInfo parent_info; @@ -323,6 +326,9 @@ public: final_extkey = parent_extkey; if (m_derive == DeriveType::UNHARDENED) der = parent_extkey.Derive(final_extkey, pos); } + } else if (m_cached_xpub.pubkey.IsValid() && m_derive != DeriveType::HARDENED) { + parent_extkey = final_extkey = m_cached_xpub; + if (m_derive == DeriveType::UNHARDENED) der = parent_extkey.Derive(final_extkey, pos); } else if (IsHardened()) { CExtKey xprv; if (!GetDerivedExtKey(arg, xprv)) return false; @@ -344,6 +350,11 @@ public: final_info_out = final_info_out_tmp; key_out = final_extkey.pubkey; + // We rely on the consumer to check that m_derive isn't HARDENED as above + // But we can't have already cached something in case we read something from the cache + // and parent_extkey isn't actually the parent. + if (!m_cached_xpub.pubkey.IsValid()) m_cached_xpub = parent_extkey; + if (write_cache) { // Only cache parent if there is any unhardened derivation if (m_derive != DeriveType::HARDENED) { -- cgit v1.2.3