Merge pull request #6549

82d21f5 easylogging++: sanitize log payload (moneromooo-monero)
7d0b7e8 [master] MMS: New 'config_checksum' subcommand (rbrunner7)

8 files changed, 337 insertions, 98 deletions

diff --git a/external/easylogging++/easylogging++.cc b/external/easylogging++/easylogging++.cc
index 8439bec0b..0d748c225 100644
--- a/external/easylogging++/easylogging++.cc
+++ b/external/easylogging++/easylogging++.cc
@@ -2475,6 +2475,100 @@ void DefaultLogDispatchCallback::handle(const LogDispatchData* data) {
   }
 }
 
+
+template<typename Transform>
+static inline std::string utf8canonical(const std::string &s, Transform t = [](wint_t c)->wint_t { return c; })
+{
+    std::string sc = "";
+    size_t avail = s.size();
+    const char *ptr = s.data();
+    wint_t cp = 0;
+    int bytes = 1;
+    char wbuf[8], *wptr;
+    while (avail--)
+    {
+      if ((*ptr & 0x80) == 0)
+      {
+        cp = *ptr++;
+        bytes = 1;
+      }
+      else if ((*ptr & 0xe0) == 0xc0)
+      {
+        if (avail < 1)
+          throw std::runtime_error("Invalid UTF-8");
+        cp = (*ptr++ & 0x1f) << 6;
+        cp |= *ptr++ & 0x3f;
+        --avail;
+        bytes = 2;
+      }
+      else if ((*ptr & 0xf0) == 0xe0)
+      {
+        if (avail < 2)
+          throw std::runtime_error("Invalid UTF-8");
+        cp = (*ptr++ & 0xf) << 12;
+        cp |= (*ptr++ & 0x3f) << 6;
+        cp |= *ptr++ & 0x3f;
+        avail -= 2;
+        bytes = 3;
+      }
+      else if ((*ptr & 0xf8) == 0xf0)
+      {
+        if (avail < 3)
+          throw std::runtime_error("Invalid UTF-8");
+        cp = (*ptr++ & 0x7) << 18;
+        cp |= (*ptr++ & 0x3f) << 12;
+        cp |= (*ptr++ & 0x3f) << 6;
+        cp |= *ptr++ & 0x3f;
+        avail -= 3;
+        bytes = 4;
+      }
+      else
+        throw std::runtime_error("Invalid UTF-8");
+
+      cp = t(cp);
+      if (cp <= 0x7f)
+        bytes = 1;
+      else if (cp <= 0x7ff)
+        bytes = 2;
+      else if (cp <= 0xffff)
+        bytes = 3;
+      else if (cp <= 0x10ffff)
+        bytes = 4;
+      else
+        throw std::runtime_error("Invalid code point UTF-8 transformation");
+
+      wptr = wbuf;
+      switch (bytes)
+      {
+        case 1: *wptr++ = cp; break;
+        case 2: *wptr++ = 0xc0 | (cp >> 6); *wptr++ = 0x80 | (cp & 0x3f); break;
+        case 3: *wptr++ = 0xe0 | (cp >> 12); *wptr++ = 0x80 | ((cp >> 6) & 0x3f); *wptr++ = 0x80 | (cp & 0x3f); break;
+        case 4: *wptr++ = 0xf0 | (cp >> 18); *wptr++ = 0x80 | ((cp >> 12) & 0x3f); *wptr++ = 0x80 | ((cp >> 6) & 0x3f); *wptr++ = 0x80 | (cp & 0x3f); break;
+        default: throw std::runtime_error("Invalid UTF-8");
+      }
+      *wptr = 0;
+      sc.append(wbuf, bytes);
+      cp = 0;
+      bytes = 1;
+    }
+    return sc;
+}
+
+void sanitize(std::string &s)
+{
+  s = utf8canonical(s, [](wint_t c)->wint_t {
+    if (c == 9 || c == 10 || c == 13)
+      return c;
+    if (c < 0x20)
+      return '?';
+    if (c == 0x7f)
+      return '?';
+    if (c >= 0x80 && c <= 0x9f)
+      return '?';
+    return c;
+  });
+}
+
 void DefaultLogDispatchCallback::dispatch(base::type::string_t&& rawLinePrefix, base::type::string_t&& rawLinePayload, base::type::string_t&& logLine) {
   if (m_data->dispatchAction() == base::DispatchAction::NormalLog || m_data->dispatchAction() == base::DispatchAction::FileOnlyLog) {
     if (m_data->logMessage()->logger()->m_typedConfigurations->toFile(m_data->logMessage()->level())) {
@@ -2506,6 +2600,8 @@ void DefaultLogDispatchCallback::dispatch(base::type::string_t&& rawLinePrefix,
         m_data->logMessage()->logger()->logBuilder()->setColor(el::base::utils::colorFromLevel(level), false);
         ELPP_COUT << rawLinePrefix;
         m_data->logMessage()->logger()->logBuilder()->setColor(color == el::Color::Default ? el::base::utils::colorFromLevel(level): color, color != el::Color::Default);
+        try { sanitize(rawLinePayload); }
+        catch (const std::exception &e) { rawLinePayload = "<Invalid UTF-8 in log>"; }
         ELPP_COUT << rawLinePayload;
         m_data->logMessage()->logger()->logBuilder()->setColor(el::Color::Default, false);
         ELPP_COUT << std::flush;
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index f06737b31..35b3555a2 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -86,7 +86,8 @@ set(common_private_headers
   updates.h
   aligned.h
   timings.h
-  combinator.h)
+  combinator.h
+  utf8.h)
 
 monero_private_headers(common
   ${common_private_headers})
diff --git a/src/common/utf8.h b/src/common/utf8.h
new file mode 100644
index 000000000..60247f1b2
--- /dev/null
+++ b/src/common/utf8.h
@@ -0,0 +1,114 @@
+// Copyright (c) 2019, The Monero Project
+// 
+// All rights reserved.
+// 
+// Redistribution and use in source and binary forms, with or without modification, are
+// permitted provided that the following conditions are met:
+// 
+// 1. Redistributions of source code must retain the above copyright notice, this list of
+//    conditions and the following disclaimer.
+// 
+// 2. Redistributions in binary form must reproduce the above copyright notice, this list
+//    of conditions and the following disclaimer in the documentation and/or other
+//    materials provided with the distribution.
+// 
+// 3. Neither the name of the copyright holder nor the names of its contributors may be
+//    used to endorse or promote products derived from this software without specific
+//    prior written permission.
+// 
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
+// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
+// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#pragma once 
+
+#include <cctype>
+#include <cwchar>
+#include <stdexcept>
+
+namespace tools
+{
+  template<typename T, typename Transform>
+  inline T utf8canonical(const T &s, Transform t = [](wint_t c)->wint_t { return c; })
+  {
+    T sc = "";
+    size_t avail = s.size();
+    const char *ptr = s.data();
+    wint_t cp = 0;
+    int bytes = 1;
+    char wbuf[8], *wptr;
+    while (avail--)
+    {
+      if ((*ptr & 0x80) == 0)
+      {
+        cp = *ptr++;
+        bytes = 1;
+      }
+      else if ((*ptr & 0xe0) == 0xc0)
+      {
+        if (avail < 1)
+          throw std::runtime_error("Invalid UTF-8");
+        cp = (*ptr++ & 0x1f) << 6;
+        cp |= *ptr++ & 0x3f;
+        --avail;
+        bytes = 2;
+      }
+      else if ((*ptr & 0xf0) == 0xe0)
+      {
+        if (avail < 2)
+          throw std::runtime_error("Invalid UTF-8");
+        cp = (*ptr++ & 0xf) << 12;
+        cp |= (*ptr++ & 0x3f) << 6;
+        cp |= *ptr++ & 0x3f;
+        avail -= 2;
+        bytes = 3;
+      }
+      else if ((*ptr & 0xf8) == 0xf0)
+      {
+        if (avail < 3)
+          throw std::runtime_error("Invalid UTF-8");
+        cp = (*ptr++ & 0x7) << 18;
+        cp |= (*ptr++ & 0x3f) << 12;
+        cp |= (*ptr++ & 0x3f) << 6;
+        cp |= *ptr++ & 0x3f;
+        avail -= 3;
+        bytes = 4;
+      }
+      else
+        throw std::runtime_error("Invalid UTF-8");
+
+      cp = t(cp);
+      if (cp <= 0x7f)
+        bytes = 1;
+      else if (cp <= 0x7ff)
+        bytes = 2;
+      else if (cp <= 0xffff)
+        bytes = 3;
+      else if (cp <= 0x10ffff)
+        bytes = 4;
+      else
+        throw std::runtime_error("Invalid code point UTF-8 transformation");
+
+      wptr = wbuf;
+      switch (bytes)
+      {
+        case 1: *wptr++ = cp; break;
+        case 2: *wptr++ = 0xc0 | (cp >> 6); *wptr++ = 0x80 | (cp & 0x3f); break;
+        case 3: *wptr++ = 0xe0 | (cp >> 12); *wptr++ = 0x80 | ((cp >> 6) & 0x3f); *wptr++ = 0x80 | (cp & 0x3f); break;
+        case 4: *wptr++ = 0xf0 | (cp >> 18); *wptr++ = 0x80 | ((cp >> 12) & 0x3f); *wptr++ = 0x80 | ((cp >> 6) & 0x3f); *wptr++ = 0x80 | (cp & 0x3f); break;
+        default: throw std::runtime_error("Invalid UTF-8");
+      }
+      *wptr = 0;
+      sc.append(wbuf, bytes);
+      cp = 0;
+      bytes = 1;
+    }
+    return sc;
+  }
+}
diff --git a/src/mnemonics/language_base.h b/src/mnemonics/language_base.h
index 7d2599e9a..ad09dc5fa 100644
--- a/src/mnemonics/language_base.h
+++ b/src/mnemonics/language_base.h
@@ -41,6 +41,7 @@
 #include <boost/algorithm/string.hpp>

 #include "misc_log_ex.h"

 #include "fnv1.h"

+#include "common/utf8.h"

 

 /*!

  * \namespace Language

@@ -73,78 +74,11 @@ namespace Language
     return prefix;

   }

 

-  template<typename T>

-  inline T utf8canonical(const T &s)

-  {

-    T sc = "";

-    size_t avail = s.size();

-    const char *ptr = s.data();

-    wint_t cp = 0;

-    int bytes = 1;

-    char wbuf[8], *wptr;

-    while (avail--)

-    {

-      if ((*ptr & 0x80) == 0)

-      {

-        cp = *ptr++;

-        bytes = 1;

-      }

-      else if ((*ptr & 0xe0) == 0xc0)

-      {

-        if (avail < 1)

-          throw std::runtime_error("Invalid UTF-8");

-        cp = (*ptr++ & 0x1f) << 6;

-        cp |= *ptr++ & 0x3f;

-        --avail;

-        bytes = 2;

-      }

-      else if ((*ptr & 0xf0) == 0xe0)

-      {

-        if (avail < 2)

-          throw std::runtime_error("Invalid UTF-8");

-        cp = (*ptr++ & 0xf) << 12;

-        cp |= (*ptr++ & 0x3f) << 6;

-        cp |= *ptr++ & 0x3f;

-        avail -= 2;

-        bytes = 3;

-      }

-      else if ((*ptr & 0xf8) == 0xf0)

-      {

-        if (avail < 3)

-          throw std::runtime_error("Invalid UTF-8");

-        cp = (*ptr++ & 0x7) << 18;

-        cp |= (*ptr++ & 0x3f) << 12;

-        cp |= (*ptr++ & 0x3f) << 6;

-        cp |= *ptr++ & 0x3f;

-        avail -= 3;

-        bytes = 4;

-      }

-      else

-        throw std::runtime_error("Invalid UTF-8");

-

-      cp = std::towlower(cp);

-      wptr = wbuf;

-      switch (bytes)

-      {

-        case 1: *wptr++ = cp; break;

-        case 2: *wptr++ = 0xc0 | (cp >> 6); *wptr++ = 0x80 | (cp & 0x3f); break;

-        case 3: *wptr++ = 0xe0 | (cp >> 12); *wptr++ = 0x80 | ((cp >> 6) & 0x3f); *wptr++ = 0x80 | (cp & 0x3f); break;

-        case 4: *wptr++ = 0xf0 | (cp >> 18); *wptr++ = 0x80 | ((cp >> 12) & 0x3f); *wptr++ = 0x80 | ((cp >> 6) & 0x3f); *wptr++ = 0x80 | (cp & 0x3f); break;

-        default: throw std::runtime_error("Invalid UTF-8");

-      }

-      *wptr = 0;

-      sc += T(wbuf, bytes);

-      cp = 0;

-      bytes = 1;

-    }

-    return sc;

-  }

-

   struct WordHash

   {

     std::size_t operator()(const epee::wipeable_string &s) const

     {

-      const epee::wipeable_string sc = utf8canonical(s);

+      const epee::wipeable_string sc = tools::utf8canonical(s, [](wint_t c) -> wint_t { return std::towlower(c); });

       return epee::fnv::FNV1a(sc.data(), sc.size());

     }

   };

@@ -153,8 +87,8 @@ namespace Language
   {

     bool operator()(const epee::wipeable_string &s0, const epee::wipeable_string &s1) const

     {

-      const epee::wipeable_string s0c = utf8canonical(s0);

-      const epee::wipeable_string s1c = utf8canonical(s1);

+      const epee::wipeable_string s0c = tools::utf8canonical(s0, [](wint_t c) -> wint_t { return std::towlower(c); });

+      const epee::wipeable_string s1c = tools::utf8canonical(s1, [](wint_t c) -> wint_t { return std::towlower(c); });

       return s0c == s1c;

     }

   };

diff --git a/src/simplewallet/simplewallet.cpp b/src/simplewallet/simplewallet.cpp
index bb45d9ec6..70eb278d5 100644
--- a/src/simplewallet/simplewallet.cpp
+++ b/src/simplewallet/simplewallet.cpp
@@ -255,6 +255,7 @@ namespace
   const char* USAGE_MMS_SET("mms set <option_name> [<option_value>]");
   const char* USAGE_MMS_SEND_SIGNER_CONFIG("mms send_signer_config");
   const char* USAGE_MMS_START_AUTO_CONFIG("mms start_auto_config [<label> <label> ...]");
+  const char* USAGE_MMS_CONFIG_CHECKSUM("mms config_checksum");
   const char* USAGE_MMS_STOP_AUTO_CONFIG("mms stop_auto_config");
   const char* USAGE_MMS_AUTO_CONFIG("mms auto_config <auto_config_token>");
   const char* USAGE_PRINT_RING("print_ring <key_image> | <txid>");
@@ -3465,7 +3466,7 @@ simple_wallet::simple_wallet()
                            tr("Interface with the MMS (Multisig Messaging System)\n"
                               "<subcommand> is one of:\n"
                               "  init, info, signer, list, next, sync, transfer, delete, send, receive, export, note, show, set, help\n"
-                              "  send_signer_config, start_auto_config, stop_auto_config, auto_config\n"
+                              "  send_signer_config, start_auto_config, stop_auto_config, auto_config, config_checksum\n"
                               "Get help about a subcommand with: help_advanced mms <subcommand>"));
   m_cmd_binder.set_handler("mms init",
                            boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
@@ -3534,6 +3535,10 @@ simple_wallet::simple_wallet()
                            boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
                            tr(USAGE_MMS_START_AUTO_CONFIG),
                            tr("Start auto-config at the auto-config manager's wallet by issuing auto-config tokens and optionally set others' labels"));
+  m_cmd_binder.set_handler("mms config_checksum",
+                           boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
+                           tr(USAGE_MMS_CONFIG_CHECKSUM),
+                           tr("Get a checksum that allows signers to easily check for identical MMS configuration"));
   m_cmd_binder.set_handler("mms stop_auto_config",
                            boost::bind(&simple_wallet::on_command, this, &simple_wallet::mms, _1),
                            tr(USAGE_MMS_STOP_AUTO_CONFIG),
@@ -10366,6 +10371,14 @@ bool simple_wallet::user_confirms(const std::string &question)
    return !std::cin.eof() && command_line::is_yes(answer);
 }
 
+bool simple_wallet::user_confirms_auto_config()
+{
+  message_writer(console_color_red, true) << tr("WARNING: Using MMS auto-config mechanisms is not trustless");
+  message_writer() << tr("A malicious auto-config manager could send you info about own wallets instead of other signers' info");
+  message_writer() << tr("If in doubt do not use auto-config or at least compare configs using the \"mms config_checksum\" command");
+  return user_confirms("Accept the risks and continue?");
+}
+
 bool simple_wallet::get_number_from_arg(const std::string &arg, uint32_t &number, const uint32_t lower_bound, const uint32_t upper_bound)
 {
   bool valid = false;
@@ -10518,7 +10531,7 @@ void simple_wallet::show_message(const mms::message &m)
   case mms::message_type::additional_key_set:
   case mms::message_type::note:
     display_content = true;
-    ms.get_sanitized_message_text(m, sanitized_text);
+    sanitized_text = mms::message_store::get_sanitized_text(m.content, 1000);
     break;
   default:
     display_content = false;
@@ -10867,6 +10880,11 @@ void simple_wallet::mms_next(const std::vector<std::string> &args)
         {
           break;
         }
+        if (!user_confirms_auto_config())
+        {
+          message_writer() << tr("You can use the \"mms delete\" command to delete any unwanted message");
+          break;
+        }
       }
       ms.process_signer_config(state, m.content);
       ms.stop_auto_config();
@@ -11193,6 +11211,18 @@ void simple_wallet::mms_start_auto_config(const std::vector<std::string> &args)
   list_signers(ms.get_all_signers());
 }
 
+void simple_wallet::mms_config_checksum(const std::vector<std::string> &args)
+{
+  if (args.size() != 0)
+  {
+    fail_msg_writer() << tr("Usage: mms config_checksum");
+    return;
+  }
+  mms::message_store& ms = m_wallet->get_message_store();
+  LOCK_IDLE_SCOPE();
+  message_writer() << ms.get_config_checksum();
+}
+
 void simple_wallet::mms_stop_auto_config(const std::vector<std::string> &args)
 {
   if (args.size() != 0)
@@ -11223,6 +11253,10 @@ void simple_wallet::mms_auto_config(const std::vector<std::string> &args)
     fail_msg_writer() << tr("Invalid auto-config token");
     return;
   }
+  if (!user_confirms_auto_config())
+  {
+    return;
+  }
   mms::authorized_signer me = ms.get_signer(0);
   if (me.auto_config_running)
   {
@@ -11335,6 +11369,10 @@ bool simple_wallet::mms(const std::vector<std::string> &args)
     {
       mms_start_auto_config(mms_args);
     }
+    else if (sub_command == "config_checksum")
+    {
+      mms_config_checksum(mms_args);
+    }
     else if (sub_command == "stop_auto_config")
     {
       mms_stop_auto_config(mms_args);
diff --git a/src/simplewallet/simplewallet.h b/src/simplewallet/simplewallet.h
index bf459736f..f96c05cb9 100644
--- a/src/simplewallet/simplewallet.h
+++ b/src/simplewallet/simplewallet.h
@@ -478,6 +478,7 @@ namespace cryptonote
     void ask_send_all_ready_messages();
     void check_for_messages();
     bool user_confirms(const std::string &question);
+    bool user_confirms_auto_config();
     bool get_message_from_arg(const std::string &arg, mms::message &m);
     bool get_number_from_arg(const std::string &arg, uint32_t &number, const uint32_t lower_bound, const uint32_t upper_bound); 
 
@@ -498,6 +499,7 @@ namespace cryptonote
     void mms_help(const std::vector<std::string> &args);
     void mms_send_signer_config(const std::vector<std::string> &args);
     void mms_start_auto_config(const std::vector<std::string> &args);
+    void mms_config_checksum(const std::vector<std::string> &args);
     void mms_stop_auto_config(const std::vector<std::string> &args);
     void mms_auto_config(const std::vector<std::string> &args);
   };
diff --git a/src/wallet/message_store.cpp b/src/wallet/message_store.cpp
index 25a8bd4ef..fb07b42f0 100644
--- a/src/wallet/message_store.cpp
+++ b/src/wallet/message_store.cpp
@@ -39,6 +39,7 @@
 #include "serialization/binary_utils.h"
 #include "common/base58.h"
 #include "common/util.h"
+#include "common/utf8.h"
 #include "string_tools.h"
 
 
@@ -129,18 +130,18 @@ void message_store::set_signer(const multisig_wallet_state &state,
   authorized_signer &m = m_signers[index];
   if (label)
   {
-    m.label = label.get();
+    m.label = get_sanitized_text(label.get(), 50);
   }
   if (transport_address)
   {
-    m.transport_address = transport_address.get();
+    m.transport_address = get_sanitized_text(transport_address.get(), 200);
   }
   if (monero_address)
   {
     m.monero_address_known = true;
     m.monero_address = monero_address.get();
   }
-  // Save to minimize the chance to loose that info (at least while in beta)
+  // Save to minimize the chance to loose that info
   save(state);
 }
 
@@ -202,6 +203,13 @@ void message_store::unpack_signer_config(const multisig_wallet_state &state, con
   }
   uint32_t num_signers = (uint32_t)signers.size();
   THROW_WALLET_EXCEPTION_IF(num_signers != m_num_authorized_signers, tools::error::wallet_internal_error, "Wrong number of signers in config: " + std::to_string(num_signers));
+  for (uint32_t i = 0; i < num_signers; ++i)
+  {
+    authorized_signer &m = signers[i];
+    m.label = get_sanitized_text(m.label, 50);
+    m.transport_address = get_sanitized_text(m.transport_address, 200);
+    m.auto_config_token = get_sanitized_text(m.auto_config_token, 20);
+  }
 }
 
 void message_store::process_signer_config(const multisig_wallet_state &state, const std::string &signer_config)
@@ -242,10 +250,10 @@ void message_store::process_signer_config(const multisig_wallet_state &state, co
       }
     }
     authorized_signer &modify = m_signers[take_index];
-    modify.label = m.label;  // ALWAYS set label, see comments above
+    modify.label = get_sanitized_text(m.label, 50);  // ALWAYS set label, see comments above
     if (!modify.me)
     {
-      modify.transport_address = m.transport_address;
+      modify.transport_address = get_sanitized_text(m.transport_address, 200);
       modify.monero_address_known = m.monero_address_known;
       if (m.monero_address_known)
       {
@@ -392,6 +400,45 @@ void message_store::process_auto_config_data_message(uint32_t id)
   signer.auto_config_running = false;
 }
 
+void add_hash(crypto::hash &sum, const crypto::hash &summand)
+{
+  for (uint32_t i = 0; i < crypto::HASH_SIZE; ++i)
+  {
+    uint32_t x = (uint32_t)sum.data[i];
+    uint32_t y = (uint32_t)summand.data[i];
+    sum.data[i] = (char)((x + y) % 256);
+  }
+}
+
+// Calculate a checksum that allows signers to make sure they work with an identical signer config
+// by exchanging and comparing checksums out-of-band i.e. not using the MMS;
+// Because different signers have a different order of signers in the config work with "adding"
+// individual hashes because that operation is commutative
+std::string message_store::get_config_checksum() const
+{
+  crypto::hash sum = crypto::null_hash;
+  uint32_t num = SWAP32LE(m_num_authorized_signers);
+  add_hash(sum, crypto::cn_fast_hash(&num, sizeof(num)));
+  num = SWAP32LE(m_num_required_signers);
+  add_hash(sum, crypto::cn_fast_hash(&num, sizeof(num)));
+  for (uint32_t i = 0; i < m_num_authorized_signers; ++i)
+  {
+    const authorized_signer &m = m_signers[i];
+    add_hash(sum, crypto::cn_fast_hash(m.transport_address.data(), m.transport_address.size()));
+    if (m.monero_address_known)
+    {
+      add_hash(sum, crypto::cn_fast_hash(&m.monero_address.m_spend_public_key, sizeof(m.monero_address.m_spend_public_key)));
+      add_hash(sum, crypto::cn_fast_hash(&m.monero_address.m_view_public_key, sizeof(m.monero_address.m_view_public_key)));
+    }
+  }
+  std::string checksum_bytes;
+  checksum_bytes += sum.data[0];
+  checksum_bytes += sum.data[1];
+  checksum_bytes += sum.data[2];
+  checksum_bytes += sum.data[3];
+  return epee::string_tools::buff_to_hex_nodelimer(checksum_bytes);
+}
+
 void message_store::stop_auto_config()
 {
   for (uint32_t i = 0; i < m_num_authorized_signers; ++i)
@@ -661,32 +708,38 @@ void message_store::delete_all_messages()
   m_messages.clear();
 }
 
-// Make a message text, which is "attacker controlled data", reasonably safe to display
+// Make a text, which is "attacker controlled data", reasonably safe to display
 // This is mostly geared towards the safe display of notes sent by "mms note" with a "mms show" command
-void message_store::get_sanitized_message_text(const message &m, std::string &sanitized_text) const
+std::string message_store::get_sanitized_text(const std::string &text, size_t max_length)
 {
-  sanitized_text.clear();
-
   // Restrict the size to fend of DOS-style attacks with heaps of data
-  size_t length = std::min(m.content.length(), (size_t)1000);
+  size_t length = std::min(text.length(), max_length);
+  std::string sanitized_text = text.substr(0, length);
 
-  for (size_t i = 0; i < length; ++i)
+  try
   {
-    char c = m.content[i];
-    if ((int)c < 32)
+    sanitized_text = tools::utf8canonical(sanitized_text, [](wint_t c)
     {
-      // Strip out any controls, especially ESC for getting rid of potentially dangerous
-      // ANSI escape sequences that a console window might interpret
-      c = ' ';
-    }
-    else if ((c == '<') || (c == '>'))
-    {
-      // Make XML or HTML impossible that e.g. might contain scripts that Qt might execute
-      // when displayed in the GUI wallet
-      c = ' ';
-    }
-    sanitized_text += c;
+      if ((c < 0x20) || (c == 0x7f) || (c >= 0x80 && c <= 0x9f))
+      {
+        // Strip out any controls, especially ESC for getting rid of potentially dangerous
+        // ANSI escape sequences that a console window might interpret
+        c = '?';
+      }
+      else if ((c == '<') || (c == '>'))
+      {
+        // Make XML or HTML impossible that e.g. might contain scripts that Qt might execute
+        // when displayed in the GUI wallet
+        c = '?';
+      }
+      return c;
+    });
+  }
+  catch (const std::exception &e)
+  {
+    sanitized_text = "(Illegal UTF-8 string)";
   }
+  return sanitized_text;
 }
 
 void message_store::write_to_file(const multisig_wallet_state &state, const std::string &filename)
diff --git a/src/wallet/message_store.h b/src/wallet/message_store.h
index d40daf186..9055fd776 100644
--- a/src/wallet/message_store.h
+++ b/src/wallet/message_store.h
@@ -242,6 +242,7 @@ namespace mms
     size_t add_auto_config_data_message(const multisig_wallet_state &state,
                                         const std::string &auto_config_token);
     void process_auto_config_data_message(uint32_t id);
+    std::string get_config_checksum() const;
     void stop_auto_config();
 
     // Process data just created by "me" i.e. the own local wallet, e.g. as the result of a "prepare_multisig" command
@@ -275,7 +276,7 @@ namespace mms
     void set_message_processed_or_sent(uint32_t id);
     void delete_message(uint32_t id);
     void delete_all_messages();
-    void get_sanitized_message_text(const message &m, std::string &sanitized_text) const;
+    static std::string get_sanitized_text(const std::string &text, size_t max_length);
 
     void send_message(const multisig_wallet_state &state, uint32_t id);
     bool check_for_messages(const multisig_wallet_state &state, std::vector<message> &messages);