Loki

Copyright (c) 2018 The Loki Project.
Portions Copyright (c) 2014-2019 The Monero Project.
Portions Copyright (c) 2012-2013 The Cryptonote developers.

Development resources

• Web: loki.network
• Telegram: t.me/LokiCommunity
• Mail: team@loki.network
• GitHub: https://github.com/loki-project/loki
• Discord: https://discord.gg/67GXfD6

Vulnerability disclosure

• Check out our Vulnerability Response Process, encourages prompt disclosure of any Vulnerabilities

Information

Loki is a private cryptocurrency based on Monero. Loki currently offers an incentivised full node layer, over the coming months we will be looking to support a secondary p2p network (Lokinet) and a messenger that offers private communications based on the Signal protocol (Loki Messenger).

More information on the project can be found on the website and in the whitepaper.

Loki is an open source project, and we encourage contributions from anyone with something to offer. For more information on contributing, please contact team@loki.network

Compiling Loki from source

Dependencies

The following table summarizes the tools and libraries required to build. A few of the libraries are also included in this repository (marked as "Vendored"). By default, the build uses the library installed on the system, and ignores the vendored sources. However, if no library is found installed on the system, then the vendored source will be built and used. The vendored sources are also used for statically-linked builds because distribution packages often include only shared library binaries (.so) but not static library archives (.a).

Dep	Min. version	Vendored	Debian/Ubuntu pkg	Arch pkg	Fedora	Optional	Purpose
GCC	4.7.3	NO	build-essential	base-devel	gcc	NO
CMake	3.5	NO	cmake	cmake	cmake	NO
pkg-config	any	NO	pkg-config	base-devel	pkgconf	NO
Boost	1.58	NO	libboost-all-dev	boost	boost-devel	NO	C++ libraries
OpenSSL	basically any	NO	libssl-dev	openssl	openssl-devel	NO	sha256 sum
libzmq	4.3.0	YES	libzmq3-dev	zeromq	zeromq-devel	NO	LokiMQ library
sqlite3	?	NO	libsqlite3-dev	sqlite	sqlite-devel	NO	Loki Name System
libunbound	1.4.16	NO	libunbound-dev	unbound	unbound-devel	NO	DNS resolver
libsodium	?	NO	libsodium-dev	libsodium	libsodium-devel	NO	cryptography
libunwind	any	NO	libunwind8-dev	libunwind	libunwind-devel	YES	Stack traces
liblzma	any	NO	liblzma-dev	xz	xz-devel	YES	For libunwind
libreadline	6.3.0	NO	libreadline-dev	readline	readline-devel	YES	Input editing
ldns	1.6.17	NO	libldns-dev	ldns	ldns-devel	YES	SSL toolkit
expat	1.1	NO	libexpat1-dev	expat	expat-devel	YES	XML parsing
Doxygen	any	NO	doxygen	doxygen	doxygen	YES	Documentation
Graphviz	any	NO	graphviz	graphviz	graphviz	YES	Documentation
lrelease	?	NO	qttools5-dev-tools	qt5-tools	qt5-linguist	YES	Translations
libhidapi	?	NO	libhidapi-dev	hidapi	hidapi-devel	YES	Hardware wallet
libusb	?	NO	libusb-dev	libusb	libusb-devel	YES	Hardware wallet
libprotobuf	?	NO	libprotobuf-dev	protobuf	protobuf-devel	YES	Hardware wallet
protoc	?	NO	protobuf-compiler	protobuf	protobuf-compiler	YES	Hardware wallet

[1] On Debian/Ubuntu libgtest-dev only includes sources and headers. You must build the library binary manually. This can be done with the following command sudo apt-get install libgtest-dev && cd /usr/src/gtest && sudo cmake . && sudo make && sudo mv libg* /usr/lib/

Install all dependencies at once on Debian/Ubuntu:

sudo apt update && sudo apt install build-essential cmake pkg-config libboost-all-dev libssl-dev libzmq3-dev libunbound-dev libsodium-dev libunwind8-dev liblzma-dev libreadline6-dev libldns-dev libexpat1-dev doxygen graphviz libpgm-dev libsqlite3-dev qttools5-dev-tools libhidapi-dev libusb-dev libprotobuf-dev protobuf-compiler

Install all dependencies at once on macOS with the provided Brewfile: brew update && brew bundle --file=contrib/brew/Brewfile

FreeBSD one liner for required to build dependencies pkg install git gmake cmake pkgconf boost-libs libzmq4 libsodium sqlite3

Cloning the repository

Clone recursively to pull-in needed submodule(s):

$ git clone --recursive https://github.com/loki-project/loki

If you already have a repo cloned, initialize and update:

$ cd loki && git submodule init && git submodule update

Build instructions

Loki uses the CMake build system and a top-level Makefile that invokes cmake commands as needed.

On Linux and macOS

• Install the dependencies

• Change to the root of the source code directory, change to the most recent release branch, and build:

  cd loki
  git checkout master
  make
  

  Optional: If your machine has several cores and enough memory, enable parallel build by running make -j<number of threads> instead of make. For this to be worthwhile, the machine should have one core and about 2GB of RAM available per thread.

  Note: The instructions above will compile the most stable release of the Loki software. If you would like to use and test the most recent software, use git checkout master. The master branch may contain updates that are both unstable and incompatible with release software, though testing is always encouraged.

• The resulting executables can be found in build/release/bin

• Add PATH="$PATH:$HOME/loki/build/release/bin" to .profile

• Run Loki with lokid --detach

• Optional: build and run the test suite to verify the binaries:

  make release-test
  

  NOTE: core_tests test may take a few hours to complete.

• Optional: to build binaries suitable for debugging:

  make debug
  

• Optional: to build statically-linked binaries:

  make release-static
  

Dependencies need to be built with -fPIC. Static libraries usually aren't, so you may have to build them yourself with -fPIC. Refer to their documentation for how to build them.

• Optional: build documentation in doc/html (omit HAVE_DOT=YES if graphviz is not installed):

  HAVE_DOT=YES doxygen Doxyfile
  

On the Raspberry Pi

Tested on a Raspberry Pi Zero with a clean install of minimal Raspbian Stretch (2017-09-07 or later) from https://www.raspberrypi.org/downloads/raspbian/. If you are using Raspian Jessie, please see note in the following section.

• apt-get update && apt-get upgrade to install all of the latest software

• Install the dependencies for Loki from the 'Debian' column in the table above.

• Increase the system swap size:

  sudo /etc/init.d/dphys-swapfile stop  
  sudo nano /etc/dphys-swapfile  
  CONF_SWAPSIZE=2048
  sudo /etc/init.d/dphys-swapfile start
  

• If using an external hard disk without an external power supply, ensure it gets enough power to avoid hardware issues when syncing, by adding the line "max_usb_current=1" to /boot/config.txt

• Clone Loki and checkout the most recent release version:

  git clone https://github.com/loki-project/loki.git
  cd loki
  git checkout master
  

• Build:

  make release
  

• Wait 4-6 hours

• The resulting executables can be found in build/release/bin

• Add PATH="$PATH:$HOME/loki/build/release/bin" to .profile

• Run Loki with lokid --detach

• You may wish to reduce the size of the swap file after the build has finished, and delete the boost directory from your home directory

Note for Raspbian Jessie users:

If you are using the older Raspbian Jessie image, compiling Loki is a bit more complicated. The version of Boost available in the Debian Jessie repositories is too old to use with Loki, and thus you must compile a newer version yourself. The following explains the extra steps, and has been tested on a Raspberry Pi 2 with a clean install of minimal Raspbian Jessie.

• As before, apt-get update && apt-get upgrade to install all of the latest software, and increase the system swap size

  sudo /etc/init.d/dphys-swapfile stop
  sudo nano /etc/dphys-swapfile
  CONF_SWAPSIZE=2048
  sudo /etc/init.d/dphys-swapfile start
  

• Then, install the dependencies for Loki except libunwind and libboost-all-dev

• Install the latest version of boost (this may first require invoking apt-get remove --purge libboost* to remove a previous version if you're not using a clean install):

  cd
  wget https://sourceforge.net/projects/boost/files/boost/1.64.0/boost_1_64_0.tar.bz2
  tar xvfo boost_1_64_0.tar.bz2
  cd boost_1_64_0
  ./bootstrap.sh
  sudo ./b2
  

• Wait ~8 hours

  sudo ./bjam cxxflags=-fPIC cflags=-fPIC -a install
  

• Wait ~4 hours

• From here, follow the general Raspberry Pi instructions from the "Clone loki and checkout most recent release version" step.

On Windows:

Binaries for Windows are built on Windows using the MinGW toolchain within MSYS2 environment. The MSYS2 environment emulates a POSIX system. The toolchain runs within the environment and cross-compiles binaries that can run outside of the environment as a regular Windows application.

Preparing the build environment

• Download and install the MSYS2 installer, either the 64-bit (x86_64) or the 32-bit (i686) package, depending on your system.

• Note: Installation must be on the C drive and root directory as result of Monero issue 3167.

• Open the MSYS shell via the MSYS2 MSYS shortcut in the Start Menu or "C:\msys64\msys2_shell.cmd -msys"

• Update packages using pacman:

  pacman -Syu
  

• Exit the MSYS shell using Alt+F4 when you get a warning stating: "terminate MSYS2 without returning to shell and check for updates again/for example close your terminal window instead of calling exit"

  pacman -Syu
  

• Update packages again using pacman:

    pacman -Syu  
  

• Install dependencies:

  To build for 64-bit Windows:

  pacman -S git mingw-w64-x86_64-toolchain make mingw-w64-x86_64-cmake mingw-w64-x86_64-boost mingw-w64-x86_64-openssl mingw-w64-x86_64-zeromq mingw-w64-x86_64-libsodium mingw-w64-x86_64-hidapi mingw-w64-x86_64-sqlite3
  

  To build for 32-bit Windows:

  pacman -S git mingw-w64-i686-toolchain make mingw-w64-i686-cmake mingw-w64-i686-boost mingw-w64-i686-openssl mingw-w64-i686-zeromq mingw-w64-i686-libsodium mingw-w64-i686-hidapi mingw-w64-i686-sqlite3
  

• Close and reopen the MSYS MinGW shell via MSYS2 MinGW 64-bit shortcut on 64-bit Windows or MSYS2 MinGW 32-bit shortcut on 32-bit Windows. Note that if you are running 64-bit Windows, you will have both 64-bit and 32-bit MinGW shells.

Cloning

• To git clone, run:

  git clone --recursive https://github.com/loki-project/loki.git
  

Building

• Change to the cloned directory, run:

  cd loki
  

• If you would like a specific version/tag, do a git checkout for that version. eg. 'v5.1.2'. If you don't care about the version and just want binaries from master, skip this step:

  git checkout v5.1.2
  

• If you are on a 64-bit system, run:

  make release-static-win64
  

• If you are on a 32-bit system, run:

  make release-static-win32
  

• The resulting executables can be found in build/<MinGW version>/<loki version>/release/bin

• Optional: to build Windows binaries suitable for debugging on a 64-bit system, run:

  make debug-static-win64
  

• Optional: to build Windows binaries suitable for debugging on a 32-bit system, run:

  make debug-static-win32
  

• The resulting executables can be found in build/<MinGW version>/<loki version>/debug/bin

On FreeBSD:

The project can be built from scratch by following instructions for Linux above(but use gmake instead of make). If you are running Loki in a jail, you need to add sysvsem="new" to your jail configuration, otherwise lmdb will throw the error message: Failed to open lmdb environment: Function not implemented.

On OpenBSD:

You will need to add a few packages to your system. pkg_add cmake gmake zeromq cppzmq libiconv boost.

The doxygen and graphviz packages are optional and require the xbase set. Running the test suite also requires py-requests package.

Build loki: env DEVELOPER_LOCAL_TOOLS=1 BOOST_ROOT=/usr/local gmake release-static

Note: you may encounter the following error, when compiling the latest version of loki as a normal user:

LLVM ERROR: out of memory
c++: error: unable to execute command: Abort trap (core dumped)

Then you need to increase the data ulimit size to 2GB and try again: ulimit -d 2000000

On Solaris:

The default Solaris linker can't be used, you have to install GNU ld, then run cmake manually with the path to your copy of GNU ld:

mkdir -p build/release
cd build/release
cmake -DCMAKE_LINKER=/path/to/ld -D CMAKE_BUILD_TYPE=Release ../..
cd ../..

Then you can run make as usual.

On Linux for Android (using docker):

# Build image (for ARM 32-bit)
docker build -f utils/build_scripts/android32.Dockerfile -t loki-android .
# Build image (for ARM 64-bit)
docker build -f utils/build_scripts/android64.Dockerfile -t loki-android .
# Create container
docker create -it --name loki-android loki-android bash
# Get binaries
docker cp loki-android:/src/build/release/bin .

Building portable statically linked binaries

By default, in either dynamically or statically linked builds, binaries target the specific host processor on which the build happens and are not portable to other processors. Portable binaries can be built using the following targets:

• make release-static-linux-x86_64 builds binaries on Linux on x86_64 portable across POSIX systems on x86_64 processors
• make release-static-linux-i686 builds binaries on Linux on x86_64 or i686 portable across POSIX systems on i686 processors
• make release-static-linux-armv8 builds binaries on Linux portable across POSIX systems on armv8 processors
• make release-static-linux-armv7 builds binaries on Linux portable across POSIX systems on armv7 processors
• make release-static-linux-armv6 builds binaries on Linux portable across POSIX systems on armv6 processors
• make release-static-win64 builds binaries on 64-bit Windows portable across 64-bit Windows systems
• make release-static-win32 builds binaries on 64-bit or 32-bit Windows portable across 32-bit Windows systems

Cross Compiling

You can also cross-compile static binaries on Linux for Windows and macOS with the depends system.

• make depends target=x86_64-linux-gnu for 64-bit linux binaries.
• make depends target=x86_64-w64-mingw32 for 64-bit windows binaries.
  • Requires: python3 g++-mingw-w64-x86-64 wine1.6 bc
• make depends target=x86_64-apple-darwin11 for macOS binaries.
  • Requires: cmake imagemagick libcap-dev librsvg2-bin libz-dev libbz2-dev libtiff-tools python-dev
• make depends target=i686-linux-gnu for 32-bit linux binaries.
  • Requires: g++-multilib bc
• make depends target=i686-w64-mingw32 for 32-bit windows binaries.
  • Requires: python3 g++-mingw-w64-i686
• make depends target=arm-linux-gnueabihf for armv7 binaries.
  • Requires: g++-arm-linux-gnueabihf
• make depends target=aarch64-linux-gnu for armv8 binaries.
  • Requires: g++-aarch64-linux-gnu
• make depends target=riscv64-linux-gnu for RISC V 64 bit binaries.
  • Requires: g++-riscv64-linux-gnu

The required packages are the names for each toolchain on apt. Depending on your distro, they may have different names.

Using depends might also be easier to compile Loki on Windows than using MSYS. Activate Windows Subsystem for Linux (WSL) with a distro (for example Ubuntu), install the apt build-essentials and follow the depends steps as depicted above.

The produced binaries still link libc dynamically. If the binary is compiled on a current distribution, it might not run on an older distribution with an older installation of libc. Passing -DBACKCOMPAT=ON to cmake will make sure that the binary will run on systems having at least libc version 2.17.

Installing Loki from a package

DISCLAIMER: These packages are not part of this repository or maintained by this project's contributors, and as such, do not go through the same review process to ensure their trustworthiness and security.

Packages are available for

• Docker

  # Build using all available cores
  docker build -t loki-daemon-image .
  
  # or build using a specific number of cores (reduce RAM requirement)
  docker build --build-arg NPROC=1 -t loki .
  
  # either run in foreground
  docker run -it -v /loki/chain:/root/.loki -v /loki/wallet:/wallet -p 22022:22022 loki
  
  # or in background
  docker run -it -d -v /loki/chain:/root/.loki -v /loki/wallet:/wallet -p 22022:22022 loki
  

• The build needs 3 GB space.

• Wait one hour or more. For docker, the collect_from_docker_container.sh script will automate downloading the binaries from the docker container.

Running lokid

The build places the binary in bin/ sub-directory within the build directory from which cmake was invoked (repository root by default). To run in foreground:

./bin/lokid

To list all available options, run ./bin/lokid --help. Options can be specified either on the command line or in a configuration file passed by the --config-file argument. To specify an option in the configuration file, add a line with the syntax argumentname=value, where argumentname is the name of the argument without the leading dashes, for example log-level=1.

To run in background:

./bin/lokid --log-file lokid.log --detach

To run as a systemd service, copy lokid.service to /etc/systemd/system/ and lokid.conf to /etc/. The example service assumes that the user loki exists and its home is the data directory specified in the example config.

If you're on Mac, you may need to add the --max-concurrency 1 option to loki-wallet-cli, and possibly lokid, if you get crashes refreshing.

Internationalization

See README.i18n.md.

Using Tor

There is a new, still experimental, integration with Tor. The feature allows connecting over IPv4 and Tor simulatenously - IPv4 is used for relaying blocks and relaying transactions received by peers whereas Tor is used solely for relaying transactions received over local RPC. This provides privacy and better protection against surrounding node (sybil) attacks.

While Loki isn't made to integrate with Tor, it can be used wrapped with torsocks, by setting the following configuration parameters and environment variables:

• --p2p-bind-ip 127.0.0.1 on the command line or p2p-bind-ip=127.0.0.1 in lokid.conf to disable listening for connections on external interfaces.
• --no-igd on the command line or no-igd=1 in lokid.conf to disable IGD (UPnP port forwarding negotiation), which is pointless with Tor.
• DNS_PUBLIC=tcp or DNS_PUBLIC=tcp://x.x.x.x where x.x.x.x is the IP of the desired DNS server, for DNS requests to go over TCP, so that they are routed through Tor. When IP is not specified, lokid uses the default list of servers defined in src/common/dns_utils.cpp.
• TORSOCKS_ALLOW_INBOUND=1 to tell torsocks to allow lokid to bind to interfaces to accept connections from the wallet. On some Linux systems, torsocks allows binding to localhost by default, so setting this variable is only necessary to allow binding to local LAN/VPN interfaces to allow wallets to connect from remote hosts. On other systems, it may be needed for local wallets as well.
• Do NOT pass --detach when running through torsocks with systemd, (see utils/systemd/lokid.service for details).
• If you use the wallet with a Tor daemon via the loopback IP (eg, 127.0.0.1:9050), then use --untrusted-daemon unless it is your own hidden service.

Example command line to start lokid through Tor:

DNS_PUBLIC=tcp torsocks lokid --p2p-bind-ip 127.0.0.1 --no-igd

Using Tor on Tails

TAILS ships with a very restrictive set of firewall rules. Therefore, you need to add a rule to allow this connection too, in addition to telling torsocks to allow inbound connections. Full example:

sudo iptables -I OUTPUT 2 -p tcp -d 127.0.0.1 -m tcp --dport 22023 -j ACCEPT
DNS_PUBLIC=tcp torsocks ./lokid --p2p-bind-ip 127.0.0.1 --no-igd --rpc-bind-ip 127.0.0.1 \
    --data-dir /home/amnesia/Persistent/your/directory/to/the/blockchain

Debugging

This section contains general instructions for debugging failed installs or problems encountered with Loki. First ensure you are running the latest version built from the Github repo.

Obtaining stack traces and core dumps on Unix systems

We generally use the tool gdb (GNU debugger) to provide stack trace functionality, and ulimit to provide core dumps in builds which crash or segfault.

• To use gdb in order to obtain a stack trace for a build that has stalled:

Run the build.

Once it stalls, enter the following command:

gdb /path/to/lokid `pidof lokid`

Type thread apply all bt within gdb in order to obtain the stack trace

• If however the core dumps or segfaults:

Enter ulimit -c unlimited on the command line to enable unlimited filesizes for core dumps

Enter echo core | sudo tee /proc/sys/kernel/core_pattern to stop cores from being hijacked by other tools

Run the build.

When it terminates with an output along the lines of "Segmentation fault (core dumped)", there should be a core dump file in the same directory as lokid. It may be named just core, or core.xxxx with numbers appended.

You can now analyse this core dump with gdb as follows:

gdb /path/to/lokid /path/to/dumpfile`

Print the stack trace with bt

• If a program crashed and cores are managed by systemd, the following can also get a stack trace for that crash:

coredumpctl -1 gdb

To run Loki within gdb:

Type gdb /path/to/lokid

Pass command-line options with --args followed by the relevant arguments

Type run to run lokid

Analysing memory corruption

There are two tools available:

ASAN

Configure Loki with the -D SANITIZE=ON cmake flag, eg:

cd build/debug && cmake -D SANITIZE=ON -D CMAKE_BUILD_TYPE=Debug ../..

You can then run the loki tools normally. Performance will typically halve.

valgrind

Install valgrind and run as valgrind /path/to/lokid. It will be very slow.

LMDB

Instructions for debugging suspected blockchain corruption as per @HYC

There is an mdb_stat command in the LMDB source that can print statistics about the database but it's not routinely built. This can be built with the following command:

cd ~/loki/external/db_drivers/liblmdb && make

The output of mdb_stat -ea <path to blockchain dir> will indicate inconsistencies in the blocks, block_heights and block_info table.

The output of mdb_dump -s blocks <path to blockchain dir> and mdb_dump -s block_info <path to blockchain dir> is useful for indicating whether blocks and block_info contain the same keys.

These records are dumped as hex data, where the first line is the key and the second line is the data.

Known Issues

Protocols

Socket-based

Because of the nature of the socket-based protocols that drive Loki, certain protocol weaknesses are somewhat unavoidable at this time. While these weaknesses can theoretically be fully mitigated, the effort required (the means) may not justify the ends. As such, please consider taking the following precautions if you are a Loki node operator:

• Run lokid on a "secured" machine. If operational security is not your forte, at a very minimum, have a dedicated a computer running lokid and do not browse the web, use email clients, or use any other potentially harmful apps on your lokid machine. Do not click links or load URL/MUA content on the same machine. Doing so may potentially exploit weaknesses in commands which accept "localhost" and "127.0.0.1".
• If you plan on hosting a public "remote" node, start lokid with --restricted-rpc. This is a must.

Blockchain-based

Certain blockchain "features" can be considered "bugs" if misused correctly. Consequently, please consider the following:

• When receiving Loki, be aware that it may be locked for an arbitrary time if the sender elected to, preventing you from spending that Loki until the lock time expires. You may want to hold off acting upon such a transaction until the unlock time lapses. To get a sense of that time, you can consider the remaining blocktime until unlock as seen in the show_transfers command.