Merge pull request #2860

3dffe71b new wipeable_string class to replace std::string passphrases (moneromooo-monero) 7a2a5741 utils: initialize easylogging++ in on_startup (moneromooo-monero) 54950829 use memwipe in a few relevant places (moneromooo-monero) 000666ff add a memwipe function (moneromooo-monero)
2024-12-23 12:09:54 +00:00 · 2017-12-16 23:19:27 +02:00 · 2017-12-16 23:19:27 +02:00 · 6c0953b15a
commit 6c0953b15a
parent ce951ef560 3dffe71b72
22 changed files with 528 additions and 69 deletions
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@ -768,3 +768,11 @@ option(BUILD_GUI_DEPS "Build GUI dependencies." OFF)
 option(INSTALL_VENDORED_LIBUNBOUND "Install libunbound binary built from source vendored with this repo." OFF)


+include(CheckCCompilerFlag)
+
+CHECK_C_COMPILER_FLAG(-std=c11 HAVE_C11)
+
+include(CheckLibraryExists)
+
+check_library_exists(c memset_s "string.h" HAVE_MEMSET_S)
+check_library_exists(c explicit_bzero "strings.h" HAVE_EXPLICIT_BZERO)
--- a/contrib/epee/include/net/http_auth.h
+++ b/contrib/epee/include/net/http_auth.h
@ -33,7 +33,7 @@
 #include <functional>
 #include <string>
 #include <utility>
-
+#include "wipeable_string.h"
 #include "http_base.h"

 #undef MONERO_DEFAULT_LOG_CATEGORY
@ -48,12 +48,12 @@ namespace net_utils
    struct login
    {
      login() : username(), password() {}
-      login(std::string username_, std::string password_)
+      login(std::string username_, wipeable_string password_)
        : username(std::move(username_)), password(std::move(password_))
      {}

      std::string username;
-      std::string password;
+      wipeable_string password;
    };

    //! Implements RFC 2617 digest auth. Digests from RFC 7616 can be added.
--- a/contrib/epee/include/wipeable_string.h
+++ b/contrib/epee/include/wipeable_string.h
@ -0,0 +1,70 @@
+// Copyright (c) 2017, 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 <stddef.h>
+#include <vector>
+#include <string>
+
+namespace epee
+{
+  class wipeable_string
+  {
+  public:
+    wipeable_string() {}
+    wipeable_string(const wipeable_string &other);
+    wipeable_string(wipeable_string &&other);
+    wipeable_string(const std::string &other);
+    wipeable_string(std::string &&other);
+    wipeable_string(const char *s);
+    ~wipeable_string();
+    void wipe();
+    void push_back(char c);
+    void pop_back();
+    const char *data() const noexcept { return buffer.data(); }
+    size_t size() const noexcept { return buffer.size(); }
+    bool empty() const noexcept { return buffer.empty(); }
+    void resize(size_t sz);
+    void reserve(size_t sz);
+    void clear();
+    bool operator==(const wipeable_string &other) const noexcept { return buffer == other.buffer; }
+    bool operator!=(const wipeable_string &other) const noexcept { return buffer != other.buffer; }
+    wipeable_string &operator=(wipeable_string &&other);
+    wipeable_string &operator=(const wipeable_string &other);
+
+    static void set_wipe(void *(*f)(void*, size_t)) { wipefunc = f; }
+
+  private:
+    void grow(size_t sz, size_t reserved = 0);
+
+  private:
+    std::vector<char> buffer;
+    static void *(*wipefunc)(void*, size_t);
+  };
+}
--- a/contrib/epee/src/CMakeLists.txt
+++ b/contrib/epee/src/CMakeLists.txt
@ -26,7 +26,7 @@
 # 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.

-add_library(epee STATIC hex.cpp http_auth.cpp mlog.cpp net_utils_base.cpp string_tools.cpp)
+add_library(epee STATIC hex.cpp http_auth.cpp mlog.cpp net_utils_base.cpp string_tools.cpp wipeable_string.cpp)
 if (USE_READLINE AND GNU_READLINE_FOUND)
  add_library(epee_readline STATIC readline_buffer.cpp)
 endif()
--- a/contrib/epee/src/http_auth.cpp
+++ b/contrib/epee/src/http_auth.cpp
@ -125,6 +125,14 @@ namespace
      {
        (*this)(boost::string_ref(arg));
      }
+      void operator()(const epee::wipeable_string& arg) const
+      {
+        md5::MD5Update(
+          std::addressof(ctx),
+          reinterpret_cast<const std::uint8_t*>(arg.data()),
+          arg.size()
+        );
+      }

      md5::MD5_CTX& ctx;
    };
--- a/contrib/epee/src/wipeable_string.cpp
+++ b/contrib/epee/src/wipeable_string.cpp
@ -0,0 +1,146 @@
+// Copyright (c) 2017, 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.
+
+#include <string.h>
+#include "misc_log_ex.h"
+#include "wipeable_string.h"
+
+namespace epee
+{
+
+void *(*wipeable_string::wipefunc)(void*, size_t) = NULL;
+
+wipeable_string::wipeable_string(const wipeable_string &other):
+  buffer(other.buffer)
+{
+}
+
+wipeable_string::wipeable_string(wipeable_string &&other)
+{
+  if (&other == this)
+    return;
+  buffer = std::move(other.buffer);
+}
+
+wipeable_string::wipeable_string(const std::string &other)
+{
+  grow(other.size());
+  memcpy(buffer.data(), other.c_str(), size());
+}
+
+wipeable_string::wipeable_string(std::string &&other)
+{
+  CHECK_AND_ASSERT_THROW_MES(wipefunc, "wipefunc is not set");
+  grow(other.size());
+  memcpy(buffer.data(), other.c_str(), size());
+  if (!other.empty())
+  {
+    wipefunc(&other[0], other.size()); // we're kinda left with this again aren't we
+    other = std::string();
+  }
+}
+
+wipeable_string::wipeable_string(const char *s)
+{
+  grow(strlen(s));
+  memcpy(buffer.data(), s, size());
+}
+
+wipeable_string::~wipeable_string()
+{
+  wipe();
+}
+
+void wipeable_string::wipe()
+{
+  CHECK_AND_ASSERT_THROW_MES(wipefunc, "wipefunc is not set");
+  wipefunc(buffer.data(), buffer.size() * sizeof(char));
+}
+
+void wipeable_string::grow(size_t sz, size_t reserved)
+{
+  CHECK_AND_ASSERT_THROW_MES(wipefunc, "wipefunc is not set");
+  if (reserved == 0)
+    reserved = sz;
+  CHECK_AND_ASSERT_THROW_MES(reserved >= sz, "reserved < sz");
+  if (reserved <= buffer.capacity())
+    return;
+  size_t old_sz = buffer.size();
+  std::unique_ptr<char[]> tmp{new char[old_sz]};
+  memcpy(tmp.get(), buffer.data(), old_sz * sizeof(char));
+  wipefunc(buffer.data(), old_sz * sizeof(char));
+  buffer.reserve(reserved);
+  buffer.resize(sz);
+  memcpy(buffer.data(), tmp.get(), sz * sizeof(char));
+  wipefunc(tmp.get(), old_sz * sizeof(char));
+}
+
+void wipeable_string::push_back(char c)
+{
+  grow(size() + 1);
+  buffer.push_back(c);
+}
+
+void wipeable_string::pop_back()
+{
+  resize(size() - 1);
+}
+
+void wipeable_string::resize(size_t sz)
+{
+  CHECK_AND_ASSERT_THROW_MES(wipefunc, "wipefunc is not set");
+  if (sz < buffer.size())
+    wipefunc(buffer.data() + sz, buffer.size() - sz);
+  grow(sz);
+}
+
+void wipeable_string::reserve(size_t sz)
+{
+  grow(size(), sz);
+}
+
+void wipeable_string::clear()
+{
+  resize(0);
+}
+
+wipeable_string &wipeable_string::operator=(wipeable_string &&other)
+{
+  if (&other != this)
+    buffer = std::move(other.buffer);
+  return *this;
+}
+
+wipeable_string &wipeable_string::operator=(const wipeable_string &other)
+{
+  if (&other != this)
+    buffer = other.buffer;
+  return *this;
+}
+
+}
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@ -35,6 +35,7 @@ set(common_sources
  download.cpp
  util.cpp
  i18n.cpp
+  memwipe.c
  password.cpp
  perf_timer.cpp
  threadpool.cpp
@ -63,6 +64,7 @@ set(common_private_headers
  util.h
  varint.h
  i18n.h
+  memwipe.h
  password.h
  perf_timer.h
  stack_trace.h
@ -90,5 +92,9 @@ target_link_libraries(common
    ${OPENSSL_LIBRARIES}
    ${EXTRA_LIBRARIES})

+if(HAVE_C11)
+SET_PROPERTY(SOURCE memwipe.c PROPERTY COMPILE_FLAGS -std=c11)
+endif()
+
 #monero_install_headers(common
 #  ${common_headers})
--- a/src/common/memwipe.c
+++ b/src/common/memwipe.c
@ -0,0 +1,106 @@
+// Copyright (c) 2017, 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.
+//
+// Parts of this file Copyright (c) 2009-2015 The Bitcoin Core developers
+
+#define __STDC_WANT_LIB_EXT1__ 1
+#include <string.h>
+#include <stdlib.h>
+#ifdef HAVE_EXPLICIT_BZERO
+#include <strings.h>
+#endif
+#include "memwipe.h"
+
+#if defined(_MSC_VER)
+#define SCARECROW \
+    __asm;
+#else
+#define SCARECROW \
+    __asm__ __volatile__("" : : "r"(ptr) : "memory");
+#endif
+
+#ifdef HAVE_MEMSET_S
+
+void *memwipe(void *ptr, size_t n)
+{
+  if (memset_s(ptr, n, 0, n))
+  {
+    abort();
+  }
+  SCARECROW // might as well...
+  return ptr;
+}
+
+#elif defined HAVE_EXPLICIT_BZERO
+
+void *memwipe(void *ptr, size_t n)
+{
+  explicit_bzero(ptr, n);
+  SCARECROW
+  return ptr;
+}
+
+#else
+
+/* The memory_cleanse implementation is taken from Bitcoin */
+
+/* Compilers have a bad habit of removing "superfluous" memset calls that
+ * are trying to zero memory. For example, when memset()ing a buffer and
+ * then free()ing it, the compiler might decide that the memset is
+ * unobservable and thus can be removed.
+ *
+ * Previously we used OpenSSL which tried to stop this by a) implementing
+ * memset in assembly on x86 and b) putting the function in its own file
+ * for other platforms.
+ *
+ * This change removes those tricks in favour of using asm directives to
+ * scare the compiler away. As best as our compiler folks can tell, this is
+ * sufficient and will continue to be so.
+ *
+ * Adam Langley <agl@google.com>
+ * Commit: ad1907fe73334d6c696c8539646c21b11178f20f
+ * BoringSSL (LICENSE: ISC)
+ */
+static void memory_cleanse(void *ptr, size_t len)
+{
+    memset(ptr, 0, len);
+
+    /* As best as we can tell, this is sufficient to break any optimisations that
+       might try to eliminate "superfluous" memsets. If there's an easy way to
+       detect memset_s, it would be better to use that. */
+    SCARECROW
+}
+
+void *memwipe(void *ptr, size_t n)
+{
+  memory_cleanse(ptr, n);
+  SCARECROW
+  return ptr;
+}
+
+#endif
--- a/src/common/memwipe.h
+++ b/src/common/memwipe.h
@ -0,0 +1,41 @@
+// Copyright (c) 2017, 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.
+// 
+// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
+
+#pragma once
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+void *memwipe(void *src, size_t n);
+
+#ifdef __cplusplus
+}
+#endif
--- a/src/common/password.cpp
+++ b/src/common/password.cpp
@ -46,6 +46,8 @@
  #include "readline_buffer.h"
 #endif

+#include "common/memwipe.h"
+
 namespace
 {
 #if defined(_WIN32)
@ -54,7 +56,7 @@ namespace
    return 0 != _isatty(_fileno(stdin));
  }

-  bool read_from_tty(std::string& pass)
+  bool read_from_tty(epee::wipeable_string& pass)
  {
    static constexpr const char BACKSPACE = 8;

@ -86,8 +88,7 @@ namespace
      {
        if (!pass.empty())
        {
-          pass.back() = '\0';
-          pass.resize(pass.size() - 1);
+          pass.pop_back();
        }
      }
      else
@ -125,7 +126,7 @@ namespace
    return ch;
  }

-  bool read_from_tty(std::string& aPass)
+  bool read_from_tty(epee::wipeable_string& aPass)
  {
    static constexpr const char BACKSPACE = 127;

@ -146,8 +147,7 @@ namespace
      {
        if (!aPass.empty())
        {
-          aPass.back() = '\0';
-          aPass.resize(aPass.size() - 1);
+          aPass.pop_back();
        }
      }
      else
@ -161,14 +161,7 @@ namespace

 #endif // end !WIN32

-  void clear(std::string& pass) noexcept
-  {
-    //! TODO Call a memory wipe function that hopefully is not optimized out
-    pass.replace(0, pass.capacity(), pass.capacity(), '\0');
-    pass.clear();
-  }
-
-  bool read_from_tty(const bool verify, const char *message, std::string& pass1, std::string& pass2)
+  bool read_from_tty(const bool verify, const char *message, epee::wipeable_string& pass1, epee::wipeable_string& pass2)
  {
    while (true)
    {
@ -184,8 +177,8 @@ namespace
        if(pass1!=pass2)
        {
          std::cout << "Passwords do not match! Please try again." << std::endl;
-          clear(pass1);
-          clear(pass2);
+          pass1.clear();
+          pass2.clear();
        }
        else //new password matches
          return true;
@ -198,7 +191,7 @@ namespace
    return false;
  }

-  bool read_from_file(std::string& pass)
+  bool read_from_file(epee::wipeable_string& pass)
  {
    pass.reserve(tools::password_container::max_password_size);
    for (size_t i = 0; i < tools::password_container::max_password_size; ++i)
@ -233,7 +226,7 @@ namespace tools

  password_container::~password_container() noexcept
  {
-    clear(m_password);
+    m_password.clear();
  }

  boost::optional<password_container> password_container::prompt(const bool verify, const char *message)
@ -249,9 +242,8 @@ namespace tools
  boost::optional<login> login::parse(std::string&& userpass, bool verify, const std::function<boost::optional<password_container>(bool)> &prompt)
  {
    login out{};
-    password_container wipe{std::move(userpass)};

-    const auto loc = wipe.password().find(':');
+    const auto loc = userpass.find(':');
    if (loc == std::string::npos)
    {
      auto result = prompt(verify);
@ -262,10 +254,11 @@ namespace tools
    }
    else
    {
-      out.password = password_container{wipe.password().substr(loc + 1)};
+      out.password = password_container{userpass.substr(loc + 1)};
    }

-    out.username = wipe.password().substr(0, loc);
+    out.username = userpass.substr(0, loc);
+    password_container wipe{std::move(userpass)};
    return {std::move(out)};
  }
 } 
--- a/src/common/password.h
+++ b/src/common/password.h
@ -32,6 +32,7 @@

 #include <string>
 #include <boost/optional/optional.hpp>
+#include "wipeable_string.h"

 namespace tools
 {
@ -58,11 +59,10 @@ namespace tools
    password_container& operator=(const password_container&) = delete;
    password_container& operator=(password_container&&) = default;

-    const std::string& password() const noexcept { return m_password; }
+    const epee::wipeable_string &password() const noexcept { return m_password; }

  private:
-    //! TODO Custom allocator that locks to RAM?
-    std::string m_password;
+    epee::wipeable_string m_password;
  };

  struct login
--- a/src/common/util.cpp
+++ b/src/common/util.cpp
@ -36,9 +36,11 @@

 #include "include_base_utils.h"
 #include "file_io_utils.h"
+#include "wipeable_string.h"
 using namespace epee;

 #include "util.h"
+#include "memwipe.h"
 #include "cryptonote_config.h"
 #include "net/http_client.h"                        // epee::net_utils::...

@ -542,6 +544,10 @@ std::string get_nix_version_display_string()
  }
  bool on_startup()
  {
+    wipeable_string::set_wipe(&memwipe);
+
+    mlog_configure("", true);
+
    sanitize_locale();

 #ifdef __GLIBC__
--- a/src/crypto/chacha8.h
+++ b/src/crypto/chacha8.h
@ -39,6 +39,7 @@
 #if defined(__cplusplus)
 #include <memory.h>

+#include "common/memwipe.h"
 #include "hash.h"

 namespace crypto {
@ -54,7 +55,7 @@ namespace crypto {

    ~chacha8_key()
    {
-      memset(data, 0, sizeof(data));
+      memwipe(data, sizeof(data));
    }
  };

@ -75,7 +76,7 @@ namespace crypto {
    char pwd_hash[HASH_SIZE];
    crypto::cn_slow_hash(data, size, pwd_hash);
    memcpy(&key, pwd_hash, sizeof(key));
-    memset(pwd_hash, 0, sizeof(pwd_hash));
+    memwipe(pwd_hash, sizeof(pwd_hash));
  }

  inline void generate_chacha8_key(std::string password, chacha8_key& key) {
--- a/src/cryptonote_basic/cryptonote_format_utils.cpp
+++ b/src/cryptonote_basic/cryptonote_format_utils.cpp
@ -32,6 +32,7 @@
 using namespace epee;

 #include <atomic>
+#include "wipeable_string.h"
 #include "cryptonote_format_utils.h"
 #include "cryptonote_config.h"
 #include "crypto/crypto.h"
@ -994,7 +995,7 @@ namespace cryptonote
    block_hashes_cached = block_hashes_cached_count;
  }
  //---------------------------------------------------------------
-  crypto::secret_key encrypt_key(crypto::secret_key key, const std::string &passphrase)
+  crypto::secret_key encrypt_key(crypto::secret_key key, const epee::wipeable_string &passphrase)
  {
    crypto::hash hash;
    crypto::cn_slow_hash(passphrase.data(), passphrase.size(), hash);
@ -1002,7 +1003,7 @@ namespace cryptonote
    return key;
  }
  //---------------------------------------------------------------
-  crypto::secret_key decrypt_key(crypto::secret_key key, const std::string &passphrase)
+  crypto::secret_key decrypt_key(crypto::secret_key key, const epee::wipeable_string &passphrase)
  {
    crypto::hash hash;
    crypto::cn_slow_hash(passphrase.data(), passphrase.size(), hash);
--- a/src/cryptonote_basic/cryptonote_format_utils.h
+++ b/src/cryptonote_basic/cryptonote_format_utils.h
@ -38,6 +38,11 @@
 #include "crypto/hash.h"
 #include <unordered_map>

+namespace epee
+{
+  class wipeable_string;
+}
+
 namespace cryptonote
 {
  //---------------------------------------------------------------
@ -226,8 +231,8 @@ namespace cryptonote
  bool is_valid_decomposed_amount(uint64_t amount);
  void get_hash_stats(uint64_t &tx_hashes_calculated, uint64_t &tx_hashes_cached, uint64_t &block_hashes_calculated, uint64_t & block_hashes_cached);

-  crypto::secret_key encrypt_key(crypto::secret_key key, const std::string &passphrase);
-  crypto::secret_key decrypt_key(crypto::secret_key key, const std::string &passphrase);
+  crypto::secret_key encrypt_key(crypto::secret_key key, const epee::wipeable_string &passphrase);
+  crypto::secret_key decrypt_key(crypto::secret_key key, const epee::wipeable_string &passphrase);
 #define CHECKED_GET_SPECIFIC_VARIANT(variant_var, specific_type, variable_name, fail_return_val) \
  CHECK_AND_ASSERT_MES(variant_var.type() == typeid(specific_type), fail_return_val, "wrong variant type: " << variant_var.type().name() << ", expected " << typeid(specific_type).name()); \
  specific_type& variable_name = boost::get<specific_type>(variant_var);
--- a/src/simplewallet/simplewallet.cpp
+++ b/src/simplewallet/simplewallet.cpp
@ -433,7 +433,7 @@ bool simple_wallet::print_seed(bool encrypted)
      m_wallet->set_seed_language(mnemonic_language);
    }

-    std::string seed_pass;
+    epee::wipeable_string seed_pass;
    if (encrypted)
    {
      auto pwd_container = tools::password_container::prompt(true, tr("Enter optional seed encryption passphrase, empty to see raw seed"));
@ -1426,7 +1426,7 @@ bool simple_wallet::init(const boost::program_options::variables_map& vm)
      auto pwd_container = tools::password_container::prompt(false, tr("Enter seed encryption passphrase, empty if none"));
      if (std::cin.eof() || !pwd_container)
        return false;
-      std::string seed_pass = pwd_container->password();
+      epee::wipeable_string seed_pass = pwd_container->password();
      if (!seed_pass.empty())
        m_recovery_key = cryptonote::decrypt_key(m_recovery_key, seed_pass);
    }
@ -2087,12 +2087,12 @@ bool simple_wallet::open_wallet(const boost::program_options::variables_map& vm)
    fail_msg_writer() << tr("wallet file path not valid: ") << m_wallet_file;
    return false;
  }
-  std::string password;
+  epee::wipeable_string password;
  try
  {
    auto rc = tools::wallet2::make_from_file(vm, m_wallet_file, password_prompter);
    m_wallet = std::move(rc.first);
-    password = std::move(rc.second).password();
+    password = std::move(std::move(rc.second).password());
    if (!m_wallet)
    {
      return false;
--- a/src/wallet/wallet2.cpp
+++ b/src/wallet/wallet2.cpp
@ -613,7 +613,7 @@ bool wallet2::is_deterministic() const
  return keys_deterministic;
 }
 //----------------------------------------------------------------------------------------------------
-bool wallet2::get_seed(std::string& electrum_words, const std::string &passphrase) const
+bool wallet2::get_seed(std::string& electrum_words, const epee::wipeable_string &passphrase) const
 {
  bool keys_deterministic = is_deterministic();
  if (!keys_deterministic)
@ -2150,7 +2150,7 @@ bool wallet2::clear()
 * \param  watch_only     true to save only view key, false to save both spend and view keys
 * \return                Whether it was successful.
 */
-bool wallet2::store_keys(const std::string& keys_file_name, const std::string& password, bool watch_only)
+bool wallet2::store_keys(const std::string& keys_file_name, const epee::wipeable_string& password, bool watch_only)
 {
  std::string account_data;
  cryptonote::account_base account = m_account;
@ -2236,7 +2236,7 @@ bool wallet2::store_keys(const std::string& keys_file_name, const std::string& p

  // Encrypt the entire JSON object.
  crypto::chacha8_key key;
-  crypto::generate_chacha8_key(password, key);
+  crypto::generate_chacha8_key(password.data(), password.size(), key);
  std::string cipher;
  cipher.resize(account_data.size());
  keys_file_data.iv = crypto::rand<crypto::chacha8_iv>();
@ -2266,7 +2266,7 @@ namespace
 * \param keys_file_name Name of wallet file
 * \param password       Password of wallet file
 */
-bool wallet2::load_keys(const std::string& keys_file_name, const std::string& password)
+bool wallet2::load_keys(const std::string& keys_file_name, const epee::wipeable_string& password)
 {
  wallet2::keys_file_data keys_file_data;
  std::string buf;
@ -2277,7 +2277,7 @@ bool wallet2::load_keys(const std::string& keys_file_name, const std::string& pa
  r = ::serialization::parse_binary(buf, keys_file_data);
  THROW_WALLET_EXCEPTION_IF(!r, error::wallet_internal_error, "internal error: failed to deserialize \"" + keys_file_name + '\"');
  crypto::chacha8_key key;
-  crypto::generate_chacha8_key(password, key);
+  crypto::generate_chacha8_key(password.data(), password.size(), key);
  std::string account_data;
  account_data.resize(keys_file_data.account_data.size());
  crypto::chacha8(keys_file_data.account_data.data(), keys_file_data.account_data.size(), key, keys_file_data.iv, &account_data[0]);
@ -2401,7 +2401,7 @@ bool wallet2::load_keys(const std::string& keys_file_name, const std::string& pa
 * can be used prior to rewriting wallet keys file, to ensure user has entered the correct password
 *
 */
-bool wallet2::verify_password(const std::string& password) const
+bool wallet2::verify_password(const epee::wipeable_string& password) const
 {
  return verify_password(m_keys_file, password, m_watch_only);
 }
@ -2418,7 +2418,7 @@ bool wallet2::verify_password(const std::string& password) const
 * can be used prior to rewriting wallet keys file, to ensure user has entered the correct password
 *
 */
-bool wallet2::verify_password(const std::string& keys_file_name, const std::string& password, bool watch_only)
+bool wallet2::verify_password(const std::string& keys_file_name, const epee::wipeable_string& password, bool watch_only)
 {
  wallet2::keys_file_data keys_file_data;
  std::string buf;
@ -2429,7 +2429,7 @@ bool wallet2::verify_password(const std::string& keys_file_name, const std::stri
  r = ::serialization::parse_binary(buf, keys_file_data);
  THROW_WALLET_EXCEPTION_IF(!r, error::wallet_internal_error, "internal error: failed to deserialize \"" + keys_file_name + '\"');
  crypto::chacha8_key key;
-  crypto::generate_chacha8_key(password, key);
+  crypto::generate_chacha8_key(password.data(), password.size(), key);
  std::string account_data;
  account_data.resize(keys_file_data.account_data.size());
  crypto::chacha8(keys_file_data.account_data.data(), keys_file_data.account_data.size(), key, keys_file_data.iv, &account_data[0]);
@ -2466,7 +2466,7 @@ bool wallet2::verify_password(const std::string& keys_file_name, const std::stri
 * \param  two_random     Whether it is a non-deterministic wallet
 * \return                The secret key of the generated wallet
 */
-crypto::secret_key wallet2::generate(const std::string& wallet_, const std::string& password,
+crypto::secret_key wallet2::generate(const std::string& wallet_, const epee::wipeable_string& password,
  const crypto::secret_key& recovery_param, bool recover, bool two_random)
 {
  clear();
@ -2546,7 +2546,7 @@ crypto::secret_key wallet2::generate(const std::string& wallet_, const std::stri
 * \param  password       Password of wallet file
 * \param  viewkey        view secret key
 */
-void wallet2::generate(const std::string& wallet_, const std::string& password,
+void wallet2::generate(const std::string& wallet_, const epee::wipeable_string& password,
  const cryptonote::account_public_address &account_public_address,
  const crypto::secret_key& viewkey)
 {
@ -2582,7 +2582,7 @@ void wallet2::generate(const std::string& wallet_, const std::string& password,
 * \param  spendkey       spend secret key
 * \param  viewkey        view secret key
 */
-void wallet2::generate(const std::string& wallet_, const std::string& password,
+void wallet2::generate(const std::string& wallet_, const epee::wipeable_string& password,
  const cryptonote::account_public_address &account_public_address,
  const crypto::secret_key& spendkey, const crypto::secret_key& viewkey)
 {
@ -2616,7 +2616,7 @@ void wallet2::generate(const std::string& wallet_, const std::string& password,
 * \param wallet_name Name of wallet file (should exist)
 * \param password    Password for wallet file
 */
-void wallet2::rewrite(const std::string& wallet_name, const std::string& password)
+void wallet2::rewrite(const std::string& wallet_name, const epee::wipeable_string& password)
 {
  prepare_file_names(wallet_name);
  boost::system::error_code ignored_ec;
@ -2629,7 +2629,7 @@ void wallet2::rewrite(const std::string& wallet_name, const std::string& passwor
 * \param wallet_name Base name of wallet file
 * \param password    Password for wallet file
 */
-void wallet2::write_watch_only_wallet(const std::string& wallet_name, const std::string& password)
+void wallet2::write_watch_only_wallet(const std::string& wallet_name, const epee::wipeable_string& password)
 {
  prepare_file_names(wallet_name);
  boost::system::error_code ignored_ec;
@ -2765,7 +2765,7 @@ bool wallet2::generate_chacha8_key_from_secret_keys(crypto::chacha8_key &key) co
  return true;
 }
 //----------------------------------------------------------------------------------------------------
-void wallet2::load(const std::string& wallet_, const std::string& password)
+void wallet2::load(const std::string& wallet_, const epee::wipeable_string& password)
 {
  clear();
  prepare_file_names(wallet_);
@ -2916,10 +2916,10 @@ std::string wallet2::path() const
 //----------------------------------------------------------------------------------------------------
 void wallet2::store()
 {
-  store_to("", "");
+  store_to("", epee::wipeable_string());
 }
 //----------------------------------------------------------------------------------------------------
-void wallet2::store_to(const std::string &path, const std::string &password)
+void wallet2::store_to(const std::string &path, const epee::wipeable_string &password)
 {
  trim_hashchain();

--- a/src/wallet/wallet2.h
+++ b/src/wallet/wallet2.h
@ -168,7 +168,7 @@ namespace tools
    //! Just parses variables.
    static std::unique_ptr<wallet2> make_dummy(const boost::program_options::variables_map& vm, const std::function<boost::optional<password_container>(const char *, bool)> &password_prompter);

-    static bool verify_password(const std::string& keys_file_name, const std::string& password, bool watch_only);
+    static bool verify_password(const std::string& keys_file_name, const epee::wipeable_string& password, bool watch_only);

    wallet2(bool testnet = false, bool restricted = false) : m_run(true), m_callback(0), m_testnet(testnet), m_always_confirm_transfers(true), m_print_ring_members(false), m_store_tx_info(true), m_default_mixin(0), m_default_priority(0), m_refresh_type(RefreshDefault), m_auto_refresh(true), m_refresh_from_block_height(0), m_confirm_missing_payment_id(true), m_ask_password(true), m_min_output_count(0), m_min_output_value(0), m_merge_destinations(false), m_confirm_backlog(true), m_is_initialized(false), m_restricted(restricted), is_old_file_format(false), m_node_rpc_proxy(m_http_client, m_daemon_rpc_mutex), m_light_wallet(false), m_light_wallet_scanned_block_height(0), m_light_wallet_blockchain_height(0), m_light_wallet_connected(false), m_light_wallet_balance(0), m_light_wallet_unlocked_balance(0) {}

@ -398,7 +398,7 @@ namespace tools
     * \param  two_random     Whether it is a non-deterministic wallet
     * \return                The secret key of the generated wallet
     */
-    crypto::secret_key generate(const std::string& wallet, const std::string& password,
+    crypto::secret_key generate(const std::string& wallet, const epee::wipeable_string& password,
      const crypto::secret_key& recovery_param = crypto::secret_key(), bool recover = false,
      bool two_random = false);
    /*!
@ -408,7 +408,7 @@ namespace tools
     * \param  viewkey        view secret key
     * \param  spendkey       spend secret key
     */
-    void generate(const std::string& wallet, const std::string& password,
+    void generate(const std::string& wallet, const epee::wipeable_string& password,
      const cryptonote::account_public_address &account_public_address,
      const crypto::secret_key& spendkey, const crypto::secret_key& viewkey);
    /*!
@ -417,7 +417,7 @@ namespace tools
     * \param  password       Password of wallet file
     * \param  viewkey        view secret key
     */
-    void generate(const std::string& wallet, const std::string& password,
+    void generate(const std::string& wallet, const epee::wipeable_string& password,
      const cryptonote::account_public_address &account_public_address,
      const crypto::secret_key& viewkey = crypto::secret_key());
    /*!
@ -425,23 +425,23 @@ namespace tools
     * \param wallet_name Name of wallet file (should exist)
     * \param password    Password for wallet file
     */
-    void rewrite(const std::string& wallet_name, const std::string& password);
-    void write_watch_only_wallet(const std::string& wallet_name, const std::string& password);
-    void load(const std::string& wallet, const std::string& password);
+    void rewrite(const std::string& wallet_name, const epee::wipeable_string& password);
+    void write_watch_only_wallet(const std::string& wallet_name, const epee::wipeable_string& password);
+    void load(const std::string& wallet, const epee::wipeable_string& password);
    void store();
    /*!
     * \brief store_to - stores wallet to another file(s), deleting old ones
     * \param path     - path to the wallet file (keys and address filenames will be generated based on this filename)
     * \param password - password to protect new wallet (TODO: probably better save the password in the wallet object?)
     */
-    void store_to(const std::string &path, const std::string &password);
+    void store_to(const std::string &path, const epee::wipeable_string &password);

    std::string path() const;

    /*!
     * \brief verifies given password is correct for default wallet keys file
     */
-    bool verify_password(const std::string& password) const;
+    bool verify_password(const epee::wipeable_string& password) const;
    cryptonote::account_base& get_account(){return m_account;}
    const cryptonote::account_base& get_account()const{return m_account;}

@ -466,7 +466,7 @@ namespace tools
     * \brief Checks if deterministic wallet
     */
    bool is_deterministic() const;
-    bool get_seed(std::string& electrum_words, const std::string &passphrase = std::string()) const;
+    bool get_seed(std::string& electrum_words, const epee::wipeable_string &passphrase = epee::wipeable_string()) const;

    /*!
    * \brief Checks if light wallet. A light wallet sends view key to a server where the blockchain is scanned.
@ -839,13 +839,13 @@ namespace tools
     * \param  watch_only     true to save only view key, false to save both spend and view keys
     * \return                Whether it was successful.
     */
-    bool store_keys(const std::string& keys_file_name, const std::string& password, bool watch_only = false);
+    bool store_keys(const std::string& keys_file_name, const epee::wipeable_string& password, bool watch_only = false);
    /*!
     * \brief Load wallet information from wallet file.
     * \param keys_file_name Name of wallet file
     * \param password       Password of wallet file
     */
-    bool load_keys(const std::string& keys_file_name, const std::string& password);
+    bool load_keys(const std::string& keys_file_name, const epee::wipeable_string& password);
    void process_new_transaction(const crypto::hash &txid, const cryptonote::transaction& tx, const std::vector<uint64_t> &o_indices, uint64_t height, uint64_t ts, bool miner_tx, bool pool, bool double_spend_seen);
    void process_new_blockchain_entry(const cryptonote::block& b, const cryptonote::block_complete_entry& bche, const crypto::hash& bl_id, uint64_t height, const cryptonote::COMMAND_RPC_GET_BLOCKS_FAST::block_output_indices &o_indices);
    void detach_blockchain(uint64_t height);
--- a/src/wallet/wallet_rpc_server.cpp
+++ b/src/wallet/wallet_rpc_server.cpp
@ -206,7 +206,8 @@ namespace tools
        }
        std::fputs(http_login->username.c_str(), rpc_login_file.handle());
        std::fputc(':', rpc_login_file.handle());
-        std::fputs(http_login->password.c_str(), rpc_login_file.handle());
+        const epee::wipeable_string password = http_login->password;
+        std::fwrite(password.data(), 1, password.size(), rpc_login_file.handle());
        std::fflush(rpc_login_file.handle());
        if (std::ferror(rpc_login_file.handle()))
        {
--- a/tests/unit_tests/CMakeLists.txt
+++ b/tests/unit_tests/CMakeLists.txt
@ -50,6 +50,7 @@ set(unit_tests_sources
  hashchain.cpp
  http.cpp
  main.cpp
+  memwipe.cpp
  mnemonics.cpp
  mul_div.cpp
  parse_amount.cpp
@ -101,6 +102,8 @@ if (NOT MSVC)
      COMPILE_FLAGS " -Wno-undef -Wno-sign-compare")
 endif ()

+SET_PROPERTY(SOURCE memwipe.cpp PROPERTY COMPILE_FLAGS -Ofast)
+
 add_test(
  NAME    unit_tests
  COMMAND unit_tests --data-dir "${TEST_DATA_DIR}")
--- a/tests/unit_tests/http.cpp
+++ b/tests/unit_tests/http.cpp
@ -211,7 +211,7 @@ std::string get_a1(const http::login& user, const fields& src)
 {
  const std::string& realm = src.at(u8"realm");
  return boost::join(
-    std::vector<std::string>{user.username, realm, user.password}, u8":"
+    std::vector<std::string>{user.username, realm, std::string(user.password.data(), user.password.size())}, u8":"
  );
 }

--- a/tests/unit_tests/memwipe.cpp
+++ b/tests/unit_tests/memwipe.cpp
@ -0,0 +1,64 @@
+// Copyright (c) 2017, 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.
+
+#include "gtest/gtest.h"
+
+#include <stdint.h>
+#include "misc_log_ex.h"
+#include "common/memwipe.h"
+
+// Probably won't catch the optimized out case, but at least we test
+// it works in the normal case
+static void test(bool wipe)
+{
+  char *foo = (char*)malloc(4);
+  ASSERT_TRUE(foo != NULL);
+  intptr_t foop = (intptr_t)foo;
+  strcpy(foo, "bar");
+  void *bar = wipe ? memwipe(foo, 3) : memset(foo, 0, 3);
+  ASSERT_EQ(foo, bar);
+  free(foo);
+  char *quux = (char*)malloc(4); // same size, just after free, so we're likely to get the same, depending on the allocator
+  if ((intptr_t)quux == foop)
+  {
+    MDEBUG(std::hex << std::setw(8) << std::setfill('0') << *(uint32_t*)quux);
+    if (wipe) ASSERT_TRUE(!memcmp(quux, "\0\0\0", 3));
+  }
+  else MWARNING("We did not get the same location, cannot check");
+  free(quux);
+}
+
+TEST(memwipe, control)
+{
+  test(false);
+}
+
+TEST(memwipe, works)
+{
+  test(true);
+}