wallet: Split signmessage from rpcwallet

Can be reviewed with --color-moved=dimmed-zebra --color-moved-ws=ignore-all-space

src/wallet/rpc/signmessage.cpp

@@ -0,0 +1,68 @@
+// Copyright (c) 2011-2021 The Bitcoin Core developers
+// 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 <rpc/util.h>
+#include <util/message.h>
+#include <wallet/rpcwallet.h>
+#include <wallet/wallet.h>
+
+#include <univalue.h>
+
+RPCHelpMan signmessage()
+{
+    return RPCHelpMan{"signmessage",
+        "\nSign a message with the private key of an address" +
+          HELP_REQUIRING_PASSPHRASE,
+        {
+            {"address", RPCArg::Type::STR, RPCArg::Optional::NO, "The bitcoin address to use for the private key."},
+            {"message", RPCArg::Type::STR, RPCArg::Optional::NO, "The message to create a signature of."},
+        },
+        RPCResult{
+            RPCResult::Type::STR, "signature", "The signature of the message encoded in base 64"
+        },
+        RPCExamples{
+            "\nUnlock the wallet for 30 seconds\n"
+            + HelpExampleCli("walletpassphrase", "\"mypassphrase\" 30") +
+            "\nCreate the signature\n"
+            + HelpExampleCli("signmessage", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\" \"my message\"") +
+            "\nVerify the signature\n"
+            + HelpExampleCli("verifymessage", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\" \"signature\" \"my message\"") +
+            "\nAs a JSON-RPC call\n"
+            + HelpExampleRpc("signmessage", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XX\", \"my message\"")
+        },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue
+        {
+            const std::shared_ptr<const CWallet> pwallet = GetWalletForJSONRPCRequest(request);
+            if (!pwallet) return NullUniValue;
+
+            LOCK(pwallet->cs_wallet);
+
+            EnsureWalletIsUnlocked(*pwallet);
+
+            std::string strAddress = request.params[0].get_str();
+            std::string strMessage = request.params[1].get_str();
+
+            CTxDestination dest = DecodeDestination(strAddress);
+            if (!IsValidDestination(dest)) {
+                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid address");
+            }
+
+            const PKHash* pkhash = std::get_if<PKHash>(&dest);
+            if (!pkhash) {
+                throw JSONRPCError(RPC_TYPE_ERROR, "Address does not refer to key");
+            }
+
+            std::string signature;
+            SigningResult err = pwallet->SignMessage(strMessage, *pkhash, signature);
+            if (err == SigningResult::SIGNING_FAILED) {
+                throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, SigningResultString(err));
+            } else if (err != SigningResult::OK) {
+                throw JSONRPCError(RPC_WALLET_ERROR, SigningResultString(err));
+            }
+
+            return signature;
+        },
+    };
+}