rpc: add getsilentpaymentblockdata

Author: Sjors

src/index/bip352.h

@@ -24,6 +24,14 @@ static constexpr bool DEFAULT_BIP352_CT_INDEX{false};
  */
 class BIP352Index final : public BaseIndex
 {
+public:
+    /**
+     * For each block hash we store and array of transactions. For each
+     * transaction we store:
+     * - the tweaked pubkey sum
+     */
+    using tweak_index_entry = std::vector<CPubKey>;
+
 protected:
     class DB;
 

src/rpc/blockchain.cpp

@@ -20,6 +20,7 @@
 #include <deploymentstatus.h>
 #include <flatfile.h>
 #include <hash.h>
+#include <index/bip352.h>
 #include <index/blockfilterindex.h>
 #include <index/coinstatsindex.h>
 #include <interfaces/mining.h>
@@ -723,6 +724,62 @@ const RPCResult getblock_vin{
     }
 };
 
+static RPCHelpMan getsilentpaymentblockdata()
+{
+    return RPCHelpMan{"getsilentpaymentblockdata",
+                "Returns an array of hex-encoded strings data for the tweaked public key sum of candidate silent transaction inputs in each transaction.\n",
+                {
+                    {"block_hash", RPCArg::Type::STR_HEX, RPCArg::Optional::NO, "The block hash"},
+                },
+                {
+                    RPCResult{
+                        RPCResult::Type::OBJ, "", "",
+                        {
+                            {RPCResult::Type::ARR, "bip352_tweaks", "The tweaked public key for each transaction that could be a silent payment",
+                                {{RPCResult::Type::STR_HEX, "tweak", "Hex-encoded data for the public key sum of candidate silent transaction inputs in the transaction"}}
+                            }
+                        }},
+                },
+                RPCExamples{
+                    HelpExampleCli("getsilentpaymentblockdata", "\"00000000000000000002cbdf64ae445b53b545ba1e960f9e83787130d1530484\"")
+            + HelpExampleRpc("getsilentpaymentblockdata", "\"00000000000000000002cbdf64ae445b53b545ba1e960f9e83787130d1530484\"")
+                },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+{
+    // TODO: add cut-through argument, check which index to use here
+    if (!g_bip352_index) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Requires bip352index");
+    }
+
+    uint256 block_hash(ParseHashV(request.params[0], "block_hash"));
+    {
+        ChainstateManager& chainman = EnsureAnyChainman(request.context);
+        const CBlockIndex* block_index;
+        LOCK(cs_main);
+        block_index = chainman.m_blockman.LookupBlockIndex(block_hash);
+        if (!block_index) {
+            throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Block not found");
+        }
+    }
+
+    BIP352Index::tweak_index_entry tweak_index_entry;
+    if (!g_bip352_index->FindSilentPayment(block_hash, tweak_index_entry)) {
+        throw JSONRPCError(RPC_INVALID_PARAMETER, "Block has not been indexed yet");
+    }
+
+    UniValue ret(UniValue::VOBJ);
+    UniValue tweaks_res(UniValue::VARR);
+
+    for (const auto& entry : tweak_index_entry) {
+        tweaks_res.push_back(HexStr(entry));
+    }
+
+    ret.pushKV("bip352_tweaks", tweaks_res);
+    return ret;
+},
+    };
+}
+
 static RPCHelpMan getblock()
 {
     return RPCHelpMan{
@@ -3433,6 +3490,7 @@ void RegisterBlockchainRPCCommands(CRPCTable& t)
         {"blockchain", &getblockfrompeer},
         {"blockchain", &getblockhash},
         {"blockchain", &getblockheader},
+        {"blockchain", &getsilentpaymentblockdata},
         {"blockchain", &getchaintips},
         {"blockchain", &getdifficulty},
         {"blockchain", &getdeploymentinfo},

src/test/fuzz/rpc.cpp

@@ -185,6 +185,7 @@ const std::vector<std::string> RPC_COMMANDS_SAFE_FOR_FUZZING{
     "waitforblock",
     "waitforblockheight",
     "waitfornewblock",
+    "getsilentpaymentblockdata"
 };
 
 std::string ConsumeScalarRPCArgument(FuzzedDataProvider& fuzzed_data_provider, bool& good_data)

test/functional/rpc_getsilentpaymentblockdata.py

@@ -0,0 +1,90 @@
+#!/usr/bin/env python3
+# Copyright (c) 2023-present The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+#
+# Test getsilentpaymentblockdata rpc call
+#
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import (
+    assert_equal,
+)
+from test_framework.blocktools import (
+    TIME_GENESIS_BLOCK,
+)
+from test_framework.descriptors import (
+    descsum_create,
+)
+
+class GetsilentpaymentblockdataTest(BitcoinTestFramework):
+    def skip_test_if_missing_module(self):
+        self.skip_if_no_wallet()
+
+    def set_test_params(self):
+        self.num_nodes = 1
+
+        self.extra_args = [[
+            '-bip352index',
+        ]]
+
+        self.setup_clean_chain = True
+
+    def run_test(self):
+        node = self.nodes[0]
+        mocktime = 1702294115
+        node.setmocktime(mocktime)
+        node.createwallet(wallet_name="w", blank=True)
+        wallet = self.nodes[0].get_wallet_rpc("w")
+        res = wallet.importdescriptors([{
+            'desc': descsum_create('wpkh(tprv8ZgxMBicQKsPeuVhWwi6wuMQGfPKi9Li5GtX35jVNknACgqe3CY4g5xgkfDDJcmtF7o1QnxWDRYw4H5P26PXq7sbcUkEqeR4fg3Kxp2tigg/84h/1h/0h/0/*)'),
+            'timestamp': TIME_GENESIS_BLOCK,
+            'active': True,
+        },
+        {
+            'desc': descsum_create('wpkh(tprv8ZgxMBicQKsPeuVhWwi6wuMQGfPKi9Li5GtX35jVNknACgqe3CY4g5xgkfDDJcmtF7o1QnxWDRYw4H5P26PXq7sbcUkEqeR4fg3Kxp2tigg/84h/1h/0h/1/*)'),
+            'timestamp': TIME_GENESIS_BLOCK,
+            'active': True,
+            'internal': True,
+        },
+        {
+            'desc': descsum_create('tr(tprv8ZgxMBicQKsPeuVhWwi6wuMQGfPKi9Li5GtX35jVNknACgqe3CY4g5xgkfDDJcmtF7o1QnxWDRYw4H5P26PXq7sbcUkEqeR4fg3Kxp2tigg/86h/1h/0h/0/*)'),
+            'timestamp': TIME_GENESIS_BLOCK,
+            'active': True,
+        },
+        {
+            'desc': descsum_create('tr(tprv8ZgxMBicQKsPeuVhWwi6wuMQGfPKi9Li5GtX35jVNknACgqe3CY4g5xgkfDDJcmtF7o1QnxWDRYw4H5P26PXq7sbcUkEqeR4fg3Kxp2tigg/86h/1h/0h/1/*)'),
+            'timestamp': TIME_GENESIS_BLOCK,
+            'active': True,
+            'internal': True,
+        }
+        ])
+        assert all([r["success"] for r in res])
+        self.log.info("Mine fresh coins to a taproot addresses")
+        mine_tr = wallet.getnewaddress(address_type="bech32m")
+        self.generatetoaddress(node, 1, mine_tr)
+        self.generate(node, 100)
+
+        self.log.info("Blocks with only a coinbase won't have any silent payment data")
+        silent_data = node.getsilentpaymentblockdata(node.getbestblockhash())
+        assert_equal(silent_data['bip352_tweaks'], [])
+
+        self.log.info("Spending from taproot to segwit won't result in silent payment data")
+        dest_sw = wallet.getnewaddress(address_type="bech32")
+        txid = wallet.send(outputs={dest_sw: 1}, options={'change_position': 1})['txid']
+        assert_equal(txid, '4d9bc8c3b77922767b06750bd9ea83865e19e6f9ccfd8d2cc048ca7a37a32ece')
+        self.generate(node, 1)
+
+        silent_data = node.getsilentpaymentblockdata(node.getbestblockhash())
+        assert_equal(silent_data['bip352_tweaks'], [])
+
+        self.log.info("Spending (from taproot) to taproot results in silent payment data")
+        dest_tr = wallet.getnewaddress(address_type="bech32m")
+        wallet.send(outputs={dest_tr: 1}, options={'inputs': [{'txid': txid, 'vout': 1}], 'add_inputs': False, 'change_position': 1})
+        self.generate(node, 1)
+        silent_data = node.getsilentpaymentblockdata(node.getbestblockhash())
+        assert_equal(silent_data['bip352_tweaks'], ['03d05270be66782cfaa3114848c92a194b8eebb74824ffe7bcd44f5d6051e9c11f'])
+
+if __name__ == '__main__':
+    GetsilentpaymentblockdataTest(__file__).main()

test/functional/test_runner.py

@@ -343,6 +343,7 @@
     'wallet_orphanedreward.py',
     'wallet_timelock.py',
     'p2p_permissions.py',
+    'rpc_getsilentpaymentblockdata.py',
     'feature_blocksdir.py',
     'wallet_startup.py',
     'feature_remove_pruned_files_on_startup.py',