feat(wallet): add Platform key provider, data records and DIP-15 friendship keychain seams

configure.ac

@@ -2077,7 +2077,9 @@ CPPFLAGS="$CPPFLAGS_TEMP"
 if test -n "$use_sanitizers"; then
   export SECP_CFLAGS="$SECP_CFLAGS $SANITIZER_CFLAGS"
 fi
-ac_configure_args="${ac_configure_args} --disable-shared --with-pic --enable-benchmark=no --enable-module-recovery --disable-module-ecdh --disable-openssl-tests"
+dnl The ECDH module is required by the wallet's Platform key provider
+dnl (DashPay contact request encryption, wallet/platformkeys.cpp).
+ac_configure_args="${ac_configure_args} --disable-shared --with-pic --enable-benchmark=no --enable-module-recovery --enable-module-ecdh --disable-openssl-tests"
 AC_CONFIG_SUBDIRS([src/dashbls src/secp256k1])
 
 AC_OUTPUT

src/Makefile.am

@@ -478,6 +478,8 @@ BITCOIN_CORE_H = \
   wallet/hdchain.h \
   wallet/ismine.h \
   wallet/load.h \
+  wallet/platformkeys.h \
+  wallet/platformtypes.h \
   wallet/receive.h \
   wallet/rpc/util.h \
   wallet/rpc/wallet.h \
@@ -709,6 +711,7 @@ libbitcoin_wallet_a_SOURCES = \
   wallet/hdchain.cpp \
   wallet/interfaces.cpp \
   wallet/load.cpp \
+  wallet/platformkeys.cpp \
   wallet/receive.cpp \
   wallet/rpc/addresses.cpp \
   wallet/rpc/backup.cpp \

src/Makefile.test.include

@@ -224,6 +224,7 @@ if ENABLE_WALLET
 BITCOIN_TESTS += \
   wallet/test/bip39_tests.cpp \
   wallet/test/coinjoin_tests.cpp \
+  wallet/test/platformkeys_tests.cpp \
   wallet/test/psbt_wallet_tests.cpp \
   wallet/test/spend_tests.cpp \
   wallet/test/wallet_tests.cpp \

src/interfaces/wallet.h

@@ -15,6 +15,7 @@
 #include <util/message.h>
 #include <util/result.h>
 #include <util/ui_change_type.h>
+#include <wallet/platformtypes.h>
 
 #include <cstdint>
 #include <functional>
@@ -142,6 +143,26 @@ class Wallet
     //! Sign special transaction payload
     virtual bool signSpecialTxPayload(const uint256& hash, const CKeyID& keyid, std::vector<unsigned char>& vchSig) = 0;
 
+    //! Derive and return a public Platform key. The mnemonic-owning key
+    //! manager performs derivation without exposing the wallet's root seed.
+    virtual wallet::PlatformKeyResult<CPubKey> getPlatformPubKey(const wallet::PlatformKeyRequest& request) = 0;
+
+    //! Sign a 32-byte digest with a platform key (compact/recoverable ECDSA,
+    //! as used by Platform state transitions).
+    virtual wallet::PlatformKeyResult<std::vector<unsigned char>> signPlatformDigest(const wallet::PlatformKeyRequest& request,
+                                                                                     const uint256& digest) = 0;
+
+    //! ECDH shared secret between the identity authentication key
+    //! and a counterparty public key, using the libsecp256k1 ECDH KDF.
+    virtual wallet::PlatformKeyResult<SecureVector> platformECDHSecret(const wallet::IdentityAuthKey& key,
+                                                                       const CPubKey& counterparty) = 0;
+
+    //! Ensure our private DIP-15 receiving chain is imported as a ranged
+    //! descriptor and return the corresponding public chain. Derivation,
+    //! descriptor update and result publication are one wallet-locked action.
+    virtual wallet::PlatformKeyResult<wallet::FriendshipXpub> ensureFriendshipReceivingKeychain(
+        const wallet::FriendshipKeychainRequest& request) = 0;
+
     //! Return whether wallet has private key.
     virtual bool isSpendable(const CScript& script) = 0;
     virtual bool isSpendable(const CTxDestination& dest) = 0;
@@ -170,6 +191,14 @@ class Wallet
     //! Save or remove receive request.
     virtual bool setAddressReceiveRequest(const CTxDestination& dest, const std::string& id, const std::string& value) = 0;
 
+    //! Write (or, with an empty value, erase) a generic Platform data
+    //! record. Records are persisted in the wallet database and travel with
+    //! backups; they are opaque to the wallet itself.
+    virtual bool writePlatformData(const std::string& key, const std::vector<unsigned char>& value) = 0;
+
+    //! All Platform data records whose key starts with prefix.
+    virtual std::map<std::string, std::vector<unsigned char>> getPlatformData(const std::string& prefix) = 0;
+
     //! Display address on external signer
     virtual bool displayAddress(const CTxDestination& dest) = 0;
 

src/script/descriptor.cpp

@@ -187,6 +187,12 @@ struct PubkeyProvider
 
     /** Derive a private key, if private data is available in arg. */
     virtual bool GetPrivKey(int pos, const SigningProvider& arg, CKey& key) const = 0;
+
+    /** Return this key expression's root extended public key, if any. */
+    virtual bool GetRootExtPubKey(CExtPubKey& key) const { return false; }
+
+    /** Return this key expression's root extended private key, if available. */
+    virtual bool GetRootExtKey(const SigningProvider& arg, CExtKey& key) const { return false; }
 };
 
 class OriginPubkeyProvider final : public PubkeyProvider
@@ -238,6 +244,14 @@ class OriginPubkeyProvider final : public PubkeyProvider
     {
         return m_provider->GetPrivKey(pos, arg, key);
     }
+    bool GetRootExtPubKey(CExtPubKey& key) const override
+    {
+        return m_provider->GetRootExtPubKey(key);
+    }
+    bool GetRootExtKey(const SigningProvider& arg, CExtKey& key) const override
+    {
+        return m_provider->GetRootExtKey(arg, key);
+    }
 };
 
 /** An object representing a parsed constant public key in a descriptor. */
@@ -488,6 +502,15 @@ class BIP32PubkeyProvider final : public PubkeyProvider
         key = extkey.key;
         return true;
     }
+    bool GetRootExtPubKey(CExtPubKey& key) const override
+    {
+        key = m_root_extkey;
+        return true;
+    }
+    bool GetRootExtKey(const SigningProvider& arg, CExtKey& key) const override
+    {
+        return GetExtKey(arg, key);
+    }
 };
 
 /** Base class for all Descriptor implementations. */
@@ -597,6 +620,28 @@ class DescriptorImpl : public Descriptor
         return AddChecksum(ret);
     }
 
+    bool GetRootExtPubKey(CExtPubKey& out) const final
+    {
+        if (m_pubkey_args.size() == 1 && m_subdescriptor_args.empty()) {
+            return m_pubkey_args.front()->GetRootExtPubKey(out);
+        }
+        if (m_pubkey_args.empty() && m_subdescriptor_args.size() == 1) {
+            return m_subdescriptor_args.front()->GetRootExtPubKey(out);
+        }
+        return false;
+    }
+
+    bool GetRootExtKey(const SigningProvider& provider, CExtKey& out) const final
+    {
+        if (m_pubkey_args.size() == 1 && m_subdescriptor_args.empty()) {
+            return m_pubkey_args.front()->GetRootExtKey(provider, out);
+        }
+        if (m_pubkey_args.empty() && m_subdescriptor_args.size() == 1) {
+            return m_subdescriptor_args.front()->GetRootExtKey(provider, out);
+        }
+        return false;
+    }
+
     bool ToPrivateString(const SigningProvider& arg, std::string& out) const override
     {
         bool ret = ToStringHelper(&arg, out, StringType::PRIVATE);

src/script/descriptor.h

@@ -108,6 +108,14 @@ struct Descriptor {
     /** Convert the descriptor back to a string, undoing parsing. */
     virtual std::string ToString() const = 0;
 
+    /** Return the single extended public key at the root of this descriptor's
+     * key expression, if it has one. */
+    virtual bool GetRootExtPubKey(CExtPubKey& out) const { return false; }
+
+    /** Return the corresponding single extended private key when it is
+     * available from `provider`. */
+    virtual bool GetRootExtKey(const SigningProvider& provider, CExtKey& out) const { return false; }
+
     /** Whether this descriptor will return one scriptPubKey or multiple (aka is or is not combo) */
     virtual bool IsSingleType() const = 0;
 

src/test/descriptor_tests.cpp

@@ -2,6 +2,7 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+#include <key_io.h>
 #include <pubkey.h>
 #include <script/descriptor.h>
 #include <script/sign.h>
@@ -11,6 +12,7 @@
 
 #include <boost/test/unit_test.hpp>
 
+#include <array>
 #include <optional>
 #include <string>
 #include <vector>
@@ -280,6 +282,33 @@ void Check(const std::string& prv, const std::string& pub, const std::string& no
 
 BOOST_FIXTURE_TEST_SUITE(descriptor_tests, BasicTestingSetup)
 
+BOOST_AUTO_TEST_CASE(descriptor_root_extended_key)
+{
+    const std::array<std::byte, 32> seed{std::byte{1}};
+    CExtKey root;
+    root.SetSeed(seed);
+
+    FlatSigningProvider keys;
+    std::string error;
+    auto descriptor{Parse("sh(pkh(" + EncodeExtKey(root) + "/0/*))", keys, error)};
+    BOOST_REQUIRE_MESSAGE(descriptor, error);
+
+    CExtPubKey root_pub;
+    BOOST_REQUIRE(descriptor->GetRootExtPubKey(root_pub));
+    BOOST_CHECK(root_pub == root.Neuter());
+
+    CExtKey root_priv;
+    BOOST_CHECK(!descriptor->GetRootExtKey(DUMMY_SIGNING_PROVIDER, root_priv));
+    BOOST_REQUIRE(descriptor->GetRootExtKey(keys, root_priv));
+    BOOST_CHECK(root_priv == root);
+
+    FlatSigningProvider constant_keys;
+    auto constant{Parse("pk(" + HexStr(root.key.GetPubKey()) + ")", constant_keys, error)};
+    BOOST_REQUIRE_MESSAGE(constant, error);
+    BOOST_CHECK(!constant->GetRootExtPubKey(root_pub));
+    BOOST_CHECK(!constant->GetRootExtKey(keys, root_priv));
+}
+
 BOOST_AUTO_TEST_CASE(descriptor_test)
 {
     // Basic single-key compressed

src/wallet/interfaces.cpp

@@ -5,6 +5,7 @@
 #include <interfaces/wallet.h>
 
 #include <chain.h>
+#include <chainparams.h>
 #include <coinjoin/client.h>
 #include <consensus/amount.h>
 #include <interfaces/chain.h>
@@ -33,6 +34,7 @@
 #include <wallet/wallet.h>
 #include <wallet/hdchain.h>
 #include <wallet/scriptpubkeyman.h>
+#include <wallet/walletutil.h>
 #include <evo/deterministicmns.h>
 #include <masternode/sync.h>
 #include <txdb.h>
@@ -239,6 +241,25 @@ class WalletImpl : public Wallet
     {
         return m_wallet->SignSpecialTxPayload(hash, keyid, vchSig);
     }
+    wallet::PlatformKeyResult<CPubKey> getPlatformPubKey(const wallet::PlatformKeyRequest& request) override
+    {
+        return m_wallet->GetPlatformPubKey(request);
+    }
+    wallet::PlatformKeyResult<std::vector<unsigned char>> signPlatformDigest(const wallet::PlatformKeyRequest& request,
+                                                                             const uint256& digest) override
+    {
+        return m_wallet->SignPlatformDigest(request, digest);
+    }
+    wallet::PlatformKeyResult<SecureVector> platformECDHSecret(const wallet::IdentityAuthKey& key,
+                                                               const CPubKey& counterparty) override
+    {
+        return m_wallet->PlatformECDHSecret(key, counterparty);
+    }
+    wallet::PlatformKeyResult<wallet::FriendshipXpub> ensureFriendshipReceivingKeychain(
+        const wallet::FriendshipKeychainRequest& request) override
+    {
+        return m_wallet->EnsureFriendshipReceivingKeychain(request);
+    }
     bool isSpendable(const CScript& script) override
     {
         LOCK(m_wallet->cs_wallet);
@@ -316,6 +337,16 @@ class WalletImpl : public Wallet
         return value.empty() ? m_wallet->EraseAddressReceiveRequest(batch, dest, id)
                              : m_wallet->SetAddressReceiveRequest(batch, dest, id, value);
     }
+    bool writePlatformData(const std::string& key, const std::vector<unsigned char>& value) override
+    {
+        LOCK(m_wallet->cs_wallet);
+        return m_wallet->WritePlatformData(key, value);
+    }
+    std::map<std::string, std::vector<unsigned char>> getPlatformData(const std::string& prefix) override
+    {
+        LOCK(m_wallet->cs_wallet);
+        return m_wallet->GetPlatformData(prefix);
+    }
     bool displayAddress(const CTxDestination& dest) override
     {
         LOCK(m_wallet->cs_wallet);