Coin DeMixer web application offers a heuristic for deanonymization of transactions coming into and out of former BestMixer.io service. DeMixer helps to track the spending history of cryptocurrency assets laundered via BestMixer.
Coin DeMixer consolidates mixing approaches reverse-engineered from services such as Bitcoin Blender, Bitcoin Laundry, BestMixer.io, PrivCoin, Blender.io, and MixTum. Heuristic tailored for BestMixer.io was produced based on the behavior of cryptocurrency tumblers mentioned above. Although law enforcement authorities seized BestMixer.io, the heuristic and web application can be customized to support compatible (i.e., using the same principle as BestMixer) tumbling service.
This application is one of the modules of the JANE platform, which offers various mission-specific tools intended for digital forensics of computer networks. JANE follows microservice architecture and offers few containerized modules such as:
- sMaSheD - tracks IP addresses and ports of well-known mining services. It also records the availability of mining service on;
- Cryptoalarm - sends email/REST notifications triggered by the appearance of cryptocurrency address in new transactions;
- DeMixer - DeMixer applies proof-of-concept heuristic (working on BestMixer.io cluster), which can correlate incoming and outgoing transactions going via mixing services;
- Cryptoclients - Blockbook web-application offers generic blockchain explorer supporting major cryptocurrencies (e.g., BTC, ETH, LTS, DASH, ZCASH);
- Toreator - stores metadata about Tor relays including IP addresses, capabilities and time when they were active;
- MozArch - MozArch is web-application that periodically downloads, parses, decodes, and archives (in the MAFF) webpages appearing on the public Internet.
JANE and its modules are outcomes of the TARZAN project supported by the Ministry of the Interior of the Czech Republic. Coin DeMixer was developed in the frame of the master thesis of Matyáš Anton supervised by Vladimír Veselý in 2019.
The primary motivation behind DeMixer's development was a necessity to address cryptocurrency tumbling as a predominant obfuscation technique when laundering assets connected with criminal activity.
DeMixer takes incoming/outgoing Bitcoin transactions processed by BestMixer.io as input and guesses corresponding outgoing/incoming transactions based on value, service and transaction fees, and time window.
DeMixer queries official cryptocurrency client (such as Bitcoin Core available as another JANE module) via RPC. DeMixer works with clustering data provided either by WalletExplorer web application or own clustering system (through defined API).
Coin DeMixer is a web application written in PHP with the help of the Laravel framework and Guzzle HTTP client:
- PHP 7.1.3
- Laravel 5.8
- Guzzle 6.3
Coin DeMixer web application source codes are available in the followin GitHub repository folder. Deployment of JANE DeMixer module can be cloned via Git repository.
All JANE modules run as containerized microservices. Therefore, the production environment is the same for all of them. JANE uses Docker for containerization. We expect that JANE containers can operate on any containerization solution compatible with Docker (such as Podman).
JANE was developed and tested on CentOS 7/8, but it can be run on any operating system satisfying the following configuration. Here is a list of installation steps to successfully configure the hosting system:
-
enable routing for (virtual) network interface cards
/sbin/sysctl -w net.ipv4.ip_forward=1 -
enable NAT on outside facing interfaces
firewall-cmd --zone=public --add-masquerade --permanent install -
add Docker repository
yum-config-manager \
--add-repo \
https://download.docker.com/linux/centos/docker-ce.repo
-
install Docker package and its prerequisites
yum install -y docker-ce -
run Docker as system service and enable it as one of the daemons
systemctl start docker
systemctl enable docker
- install docker-compose staging application
sudo curl -L "https://github.com/docker/compose/releases/download/1.25.5/docker-compose-$(uname -s)-$(uname -m)" -o /usr/local/bin/docker-compose
chmod +x /usr/local/bin/docker-compose
cp /usr/local/bin/docker-compose /sbin/docker-compose
- install Docker add-on which allows to specify destinations for dynamically created volumes
curl -fsSL https://raw.githubusercontent.com/MatchbookLab/local-persist/master/scripts/install.sh | sudo bash
Coin DeMixer consists of two containers - Laravel 5.8 web application and nginx 1.10 HTTP server. In order to deploy DeMixer on your server:
-
clone DeMixer repository
git clone https://github.com/nesfit/jane-DeMixer.git -
copy container environmental variables file
cp .env.example .env -
specify in
.envpublic port on which DeMixer will be available and existing virtual network name nano .env
NETWORK=<docker_network>
HTTP_PORT=<public_port>
-
copy web application environmental variables file
cp ./demixer/.env.example ./demixer/.env -
specify in
./demixer/.envfollowing parameters (where for Bitcoin/Litecoin clients you may consider to deploy JANE cryptoclients module)
CLUSTER_CLIENT=<DeMixer compatible cluster provider>
BTC_CORE_HOSTNAME=<host running official Bitcoin client>
BTC_CORE_PORT=<port for RPC calls>
BTC_CORE_USERNAME=<Bitcoin client RPC username>
BTC_CORE_PASSWORD=<Bitcoin client RPC password>
LTC_CORE_HOSTNAME=<host running official Litecoin client>
LTC_CORE_PORT=<port for RPC calls>
LTC_CORE_USERNAME=<Litecoin client RPC username>
LTC_CORE_PASSWORD=<Litecoin client RPC password>
-
pull containers from Docker hub repository
docker-compose pull -
optionally build web application locally
docker-compose build demix-app -
run containers
docker-compose up -d
The heuristic works with the premise that mixing service operator (such as BestMixer.io) uses a single wallet (i.e., cluster of addresses) to handle cryptocurrency assets. This means that for any incoming transaction (i.e., mixing service user depositing assets for laundering) to the cluster, there exist one or more subsequent outgoing transactions from that same cluster returning tumbled cryptocurrencies (back to the user). Outgoing transaction(s) should satisfy the following conditions:
- to have the same value as incoming transaction minus blockchain and operator's fee
- to happen later than the incoming transaction but no later than service mixing upper bound limit
Pseudo-algorithm behind heuristic goes through these steps when determining matching outgoing transactions for a given input:
- Determine cluster C belonging to mixing service
- Remember time t of incoming transaction and its output value v
- Iterate through a list of all transactions L in blockchain from t to t + dmax, where dmax represents maximum delay for laundering, which mixing service offers
- Select only those transactions in L, which satisfy: a) has one or more addresses from C as inputs; b) has one or more addresses not from C as outputs; c) output value for any address satisfying b) equals to v – fee, where fee is in the range of acceptable fees as announced by mixing service
DeMixer is a web application that does not need any authorized user access. DeMixer consists of the following views:
- Basic search - takes incoming/outgoing transaction identifier and tries to find transactions with a corresponding value using default BestMixer.io settings (dmax equal to 72 hours, fee in the range 1-4% including 0.0004 BTC transaction/miner fee).
- Advanced search - offers further customization of heuristic parameters: a) the range of minimum/maximum service operator fees; b) the range of minimum/maximum blockchain transaction fees; and c) the time range for transaction list window
- Search results - displays a list of transactions matched by heuristic algorithm.
When using Basic search, the user inputs transaction id and marks this transaction as incoming/outgoing. Then the user may select mixing heuristic (by default the same as BestMixer.io was using, which is described above) and cluster provider (by default Tarzan). User then clicks on Search button and waits for results.
When using Advanced search, the user customizes all inputs of demixing heuristics and submits using Search.
Search results page displays possible candidates (i.e., transactions). Each candidate contains highlighted address that matched heuristics. Candidates may contain more than one transaction and in that case sum of all highligted address corresponds to the input value.
In order to have ground truth and validate Coin DeMixer heuristics, we have conducted our own attempts to mix our cryptocurrency assets using BestMixer.io. We have sent to BestMixer.io three transactions:
| TX #1 Property | Value |
|---|---|
| Incoming txid | 671bacf7b79272cab3ade1d9d3162bd96a0151542e8f337698bd1e48e65d8652 |
| Incoming address | 3KuhVxYpcCEoZezNPndTPxqnoDdsPiiM3Z |
| Outgoing txid | 8621e1c1955941037f391658c9785ab98ff76b112b3327e099dac01d19b4eacc |
| Outgoing address | 3JZVY58aSmYY6PiYM3Vb6P25nhGUhwa6QW |
| Delay | 2 hours 40 minutes |
| Deposited amount | 0.0015 BTC |
| Fee | 1% |
| Time | 8.1.2019 16:07:54 |
| TX #2 property | Value |
|---|---|
| Incoming txid | c5b452b31c2534fccb331c1837ed200b0b36437052ea5230c3d02ea6c56655e2 |
| Incoming address | 13a3hJNN9HzqrC6B5caTxoaB5UGwA8w5kA |
| Outgoing txid | d3bf0904cadd9416c1167e8ff80e7ff8801942920063505e7ef71f96d36b6d7e b9c183785845c59dcce05cd3d629256ae5b91482e6ca90275961fdebc45b778e |
| Outgoing address | 3KGVsRKZKD7aj5Qr9uyqcVHE3mNFFDTqau 3CKf9CMPShkrEY9YXgZ4mv6Dmhv8a2rb3j |
| Delay | 2 hours 40 minutes 4 hours 40 minutes |
| Deposited amount | 0.002 BTC |
| Fee | 1% |
| Time | 28.2.2019 21:52 |
| TX #3 Property | Value |
|---|---|
| Incoming txid | 29a484238d2d642702b1c559f4b613c011fe67444ea2131b95510d0848ab7585 |
| Incoming address | 36YNn7G23RFYZMHBLfNHjevWiAQs4nrhs9 |
| Outgoing txid | 7b0843e05c6f0e315808ed010b5bd6a9fd7252b45ed10564eca52d512e14b92e |
| Outgoing address | 3AEJxHHT1iuVkDNbBrcxFRHwiVDjpVzkti |
| Delay | 2 hours |
| Deposited amount | 0.0015 BTC |
| Fee | 2% |
| Time | 27.1.2019 20:12 |
The programmer's documentation for DeMixer is autogenerated with the help of phpDox. This documentation is available statically in docs folder. Moreover, for your convenience, it is also available online through JANE's landing page.
Class diagram corresponding to source codes of final application:
![@dependabot[bot]](https://avatars.githubusercontent.com/in/29110?s=64&v=4){kind=small}