From f90efbfeef9cd733aa7590fdf581ff82b999c4b5 Mon Sep 17 00:00:00 2001
From: Andrew <achow101@gmail.com>
Date: Tue, 26 Apr 2016 13:17:00 -0400
Subject: [PATCH 1/2] Create signmessagewithprivkey rpc

New rpc 'signmessagewithprivkey' which takes a private key to sign a message without using the wallet.
---
 src/rpc/misc.cpp | 43 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 43 insertions(+)

diff --git a/src/rpc/misc.cpp b/src/rpc/misc.cpp
index e8a099b44..09f518578 100644
--- a/src/rpc/misc.cpp
+++ b/src/rpc/misc.cpp
@@ -366,6 +366,48 @@ UniValue verifymessage(const UniValue& params, bool fHelp)
     return (pubkey.GetID() == keyID);
 }
 
+UniValue signmessagewithprivkey(const UniValue& params, bool fHelp)
+{
+    if (fHelp || params.size() != 2)
+        throw runtime_error(
+            "signmessagewithprivkey \"privkey\" \"message\"\n"
+            "\nSign a message with the private key of an address\n"
+            "\nArguments:\n"
+            "1. \"privkey\"         (string, required) The private key to sign the message with.\n"
+            "2. \"message\"         (string, required) The message to create a signature of.\n"
+            "\nResult:\n"
+            "\"signature\"          (string) The signature of the message encoded in base 64\n"
+            "\nExamples:\n"
+            "\nCreate the signature\n"
+            + HelpExampleCli("signmessagewithprivkey", "\"privkey\" \"my message\"") +
+            "\nVerify the signature\n"
+            + HelpExampleCli("verifymessage", "\"1D1ZrZNe3JUo7ZycKEYQQiQAWd9y54F4XZ\" \"signature\" \"my message\"") +
+            "\nAs json rpc\n"
+            + HelpExampleRpc("signmessagewithprivkey", "\"privkey\", \"my message\"")
+        );
+
+    string strPrivkey = params[0].get_str();
+    string strMessage = params[1].get_str();
+
+    CBitcoinSecret vchSecret;
+    bool fGood = vchSecret.SetString(strPrivkey);
+    if (!fGood)
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Invalid private key");
+    CKey key = vchSecret.GetKey();
+    if (!key.IsValid())
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Private key outside allowed range");
+
+    CHashWriter ss(SER_GETHASH, 0);
+    ss << strMessageMagic;
+    ss << strMessage;
+
+    vector<unsigned char> vchSig;
+    if (!key.SignCompact(ss.GetHash(), vchSig))
+        throw JSONRPCError(RPC_INVALID_ADDRESS_OR_KEY, "Sign failed");
+
+    return EncodeBase64(&vchSig[0], vchSig.size());
+}
+
 UniValue setmocktime(const UniValue& params, bool fHelp)
 {
     if (fHelp || params.size() != 1)
@@ -404,6 +446,7 @@ static const CRPCCommand commands[] =
     { "util",               "validateaddress",        &validateaddress,        true  }, /* uses wallet if enabled */
     { "util",               "createmultisig",         &createmultisig,         true  },
     { "util",               "verifymessage",          &verifymessage,          true  },
+    { "util",               "signmessagewithprivkey", &signmessagewithprivkey, true  },
 
     /* Not shown in help */
     { "hidden",             "setmocktime",            &setmocktime,            true  },

From 7db0ecb90c80bd4995bedf8c2982e9a22345ca65 Mon Sep 17 00:00:00 2001
From: Andrew Chow <achow101@gmail.com>
Date: Wed, 27 Apr 2016 12:18:20 -0700
Subject: [PATCH 2/2] Test for signing messages

New rpc test for signing and verifying messages.
---
 qa/pull-tester/rpc-tests.py  |  1 +
 qa/rpc-tests/signmessages.py | 40 ++++++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)
 create mode 100755 qa/rpc-tests/signmessages.py

diff --git a/qa/pull-tester/rpc-tests.py b/qa/pull-tester/rpc-tests.py
index c0637209e..26142c35e 100755
--- a/qa/pull-tester/rpc-tests.py
+++ b/qa/pull-tester/rpc-tests.py
@@ -123,6 +123,7 @@ testScripts = [
     'abandonconflict.py',
     'p2p-versionbits-warning.py',
     'importprunedfunds.py',
+    'signmessages.py'
 ]
 if ENABLE_ZMQ:
     testScripts.append('zmq_test.py')
diff --git a/qa/rpc-tests/signmessages.py b/qa/rpc-tests/signmessages.py
new file mode 100755
index 000000000..ff22f3530
--- /dev/null
+++ b/qa/rpc-tests/signmessages.py
@@ -0,0 +1,40 @@
+#!/usr/bin/env python2
+# Copyright (c) 2016 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import *
+
+
+class SignMessagesTest(BitcoinTestFramework):
+    """Tests RPC commands for signing and verifying messages."""
+
+    def setup_chain(self):
+        print('Initializing test directory ' + self.options.tmpdir)
+        initialize_chain_clean(self.options.tmpdir, 1)
+
+    def setup_network(self, split=False):
+        self.nodes = start_nodes(1, self.options.tmpdir)
+        self.is_network_split = False
+
+    def run_test(self):
+        message = 'This is just a test message'
+
+        # Test the signing with a privkey
+        privKey = 'cUeKHd5orzT3mz8P9pxyREHfsWtVfgsfDjiZZBcjUBAaGk1BTj7N'
+        address = 'mpLQjfK79b7CCV4VMJWEWAj5Mpx8Up5zxB'
+        signature = self.nodes[0].signmessagewithprivkey(privKey, message)
+
+        # Verify the message
+        assert(self.nodes[0].verifymessage(address, signature, message))
+
+        # Test the signing with an address with wallet
+        address = self.nodes[0].getnewaddress()
+        signature = self.nodes[0].signmessage(address, message)
+
+        # Verify the message
+        assert(self.nodes[0].verifymessage(address, signature, message))
+
+if __name__ == '__main__':
+    SignMessagesTest().main()