Particl

Particl launched in July 2017 and is a privacy-first and censorship-resistant eCommerce platform. The ecosystem currently includes the privacy coin PART and the Particl Marketplace application.

The Particl coin (PART) is a digital currency with data protection and privacy features. These include Confidential Transactions with Bulletproofs, RingCT, and stealth addresses. The Particl blockchain, which is always updated to the latest Bitcoin Core codebase, uses Particl Proof-of-Stake (PPoS), with cold staking enabled, to secure transactions.

PART acts as the settlement-layer for all transactions made on Particl Marketplace and enables its privacy capabilities. All payments, in fiat or digital currency, are automatically converted into PART with the goal of empowering users with true privacy and freedom.

Particl is an open-source, non-profit, and decentralized privacy marketplace built on blockchain that is headquartered in Zug, Switzerland and was founded by Paul Schmitzer and Ryno Mathee. Particl was officially launched in July of 2017 and is the successor of another privacy cryptocurrency project called the ShadowProject which was founded in August 2014.

Particl is designed to work with any cryptocurrency, and its native utility token is Particl (PART). PART is required for the platform's features and decentralized applications such as marketplaces, messaging and voting.

From March 17, 2017 to April 13, 2017 Particl held their initial coin offering (ICO) selling approximately $750,000 worth of their platforms native cryptocurrency utility token PART.

The Particl Platform allows anyone to use and build highly secure decentralized applications with privacy and security parameters. Dapps on the Particl Platform utilize the PART Coin for processing transactions regardless of which currency payments will be made.

PART is Particl’s native coin and has several use cases on the Particl Platform. It is a coin with a particularly strong economic model compared to most cryptocurrencies and is designed to generate demand by usage of any Particl Dapp. PART is a privacy coin, a voting right, a fuel for the Particl Platform, a potential source of passive income, and can manage a large amount of transactions without getting slower or compromising security.

Particl's Open Marketplace is a decentralized marketplace built with privacy features. It offers a low-cost, secure and scalable eCommerce experience. The Particl Open Marketplace is a hybrid between blockchain and peer-to-peer technologies. It operates with no central authority and is exclusively owned and operated by its network of participants. The Open Marketplace focuses on four core values: privacy, security, scalability, and absolute decentralization.

Particl's Open Marketplace is based on the Open Market Protocol (OMP) developed by Particl developer Kewde. It is a standardized and open format containing most of the economic interactions of an online marketplace. The OMP available as an open-source protocol on Particl's Github page and is licensed under the terms of the MIT software license.

The Open Market Protocol is divided into two distinct formats. The first one, the public listing format, contains all the necessary data related to a certain item or service listed for sale. This includes the title, description, images, payment destination, and other similar information. The other one, the private message format, contains all the data that must remain private. It includes the transaction information, the conversations between the seller and the buyer, and the buyer's address.

The protocol has few virtues in mind: extensibility and privacy. Privacy is also an important cornerstone of the OMP. The protocol specifies a format for private messages that buyers and sellers must use to communicate. We strongly recommend that these messages be exchanged over end-to-end encrypted communication channels. Recent revelations and academic papers have proven beyond a doubt that there are many active threats to our digital privacy and security. Additionally, blockchains are open public books that are full of sensitive information for passive attackers to abuse. This was of great concern when designing this protocol as it puts users at risk.

The OMP allows for full inventory data portability, but it doesn't stop there. It also lets vendors easily assign images as well as payment and shipping details to specific listings. Transferring data to other marketplaces that follow the OMP specification becomes very straightforward. The OMP payment formats operate with the Bitcoin blockchain and any derivatives. It also allows merchants to accept a multitude of virtual currencies on a per item basis.

The Open Marketplace is private by default. This means it automatically keeps users' identities and data private without requiring any extra step from the user. The only exception to that rule is the Tor setup which isn't enabled by default for security measures.

All payments and transactions made on the Open Marketplace are untraceable by default. This is achieved by leveraging the Confidential Transactions (CT) and RingCT capabilities of the Particl coin (PART). These two protocols are integrated as the default types of payments, as specified by the OMP. Click here to learn how the Open Market Protocol specifies payments.

CT and RingCT transactions have been historically used on the Cryptonote codebase. Yet, the Particl team has adapted these protocols to be compatible with the Bitcoin codebase, which is the codebase used for the PART coin. The Bitcoin codebase gives more flexibility, security, and stability to the PART coin that the Cryptonote codebase would. A good example for this is the ability for the RingCT and CT protocols to interact with smart-contracts (i.e. the Open Marketplace). The coin also uses the Bulletproofs CT protocol improvement (currently on testnet) which reduces range proofs by about 70%. This ensures marketplace payments are both anonymous and scalable at the same time.

The Open Marketplace does not generate any sort of traceable data. That much is true whether you are a buyer or a vendor. Metadata is “data about data” and can be very useful to track users. For example, pictures usually carry data such as the device used to take the picture, when it was taken, and even the precise geo-location of where the picture was taken. Any data stored off-chain on Particl's network is immediately stripped of all its metadata, making it impossible to trace people using metadata. This behavior is enabled by Particl's SMSG Data Storage Network.

IP addresses can easily be anonymized on the Open Marketplace by installing Tor and editing the configuration file of your Particl Desktop client. Doing so shields you from getting your real IP address to be broadcast to the network. Particl Desktop currently doesn't automatically route connections through Tor for security measures. If that were the case, a new Particl Desktop version would need to be installed by the user every time Tor pushes a new update. Automatic Tor updates, on the other hand, introduce severe security vulnerabilities, especially in regards to the authenticity of the files being automatically pushed to the client. The Particl team is aware of a few solutions to circumvent this issue. It is also looking into alternatives to Tor. Automatic IP address anonymization should make their way onto Particl Desktop in the future. Click here to learn how to set your Particl Desktop client as a Tor hidden service.

Open listings on Particl's Open Marketplace are listings that are publicly available. Anyone can search for these listings using keywords and by navigating to the correct categories. Although these listings are public, they still offer a great level of privacy as all transactions are untraceable by default. The only “identifiable” data public listings reveal is a unique and anonymous vendor ID. This ID cannot, however, link to any payment address or traceable identity.

Private Markets are independent markets generated by users. They are not accessible from the public interface of the Open Marketplace. The only way to access them is by entering their unique Market ID in the Particl Desktop client. The Market ID is only known to the person that initially generated the private market and to the people he shared it with. While private markets aren't part of the first mainnet version of the Open Marketplace, they will be implemented during the Beta phase of development. They each will have their own group chat where users can communicate with each other. They are, in a sense, sub-communities.

Private Listings are not publicly available on the Open Marketplace and live inside private markets. They can only be accessed by first connecting to a private market, thus benefiting from an extra layer of privacy. These listings are ideal for one-to-one deals, sub-communities, and for when vendors want to sell items but not have them show up on the public interface of the marketplace.

As buyers and vendors do not know and trust each other, there has to be protection against one of the party never honoring their end of the trade. One common solution marketplaces and payment processors use is a mutually-trusted third party (in other words, an escrow agent). On decentralized marketplaces, not only does this represents scalability and privacy issues but it also does not offer any protection against collusion between the escrow agent and one of the party. Particl's Open Marketplace solves this problem without the need for a third party. It uses what is called MAD escrow smart-contracts. This type of escrow does not cost any fee, is infinitely scalable and private by design.

Mutually Assured Destruction (MAD) is a doctrine of military strategy and national security policy in which a full-scale use of nuclear weapons by two or more opposing sides would cause the complete annihilation of both the attacker and the defender, thus making their use not an option. It is based on the theory of deterrence, which holds that the threat of using strong weapons against the enemy prevents the enemy's use of those same weapons. The strategy is a form of Nash equilibrium in which, once armed, neither side has any incentive to initiate a conflict or to disarm. Particl’s MAD escrow mechanism replaces the nuclear annihilation deterrence factor of the MAD game theory for a mutual financial loss should one party acts dishonestly.

Particl uses the BIP 65 opcode, which allows a transaction output to be made unspendable until some point in the future, to enable MAD escrow contracts. It locks funds in a secure multi-signature address until all the parties sign off on the transaction.

The seller starts by depositing an amount they want the buyer to match. The deposit can be between 0 and 100 percent of the purchased item’s price. However, optimal MAD odds are achieved when the security deposit equals 100 percent of the item’s price. The buyer then deposits an equal amount plus the price of the item they are buying. This double security deposit symbolizes a virtual handshake between the buyer and the vendor.

The escrowed funds are not released to any party until both confirm that the transaction has been completed satisfactorily. To avoid filibustering, the MAD smart-contract has a timer that runs for a pre-determined duration of time. This can be extended if both parties agree. Once it runs out of time, the funds are locked forever. This prevents both parties from willingly delaying and hindering the escrow process.

When both parties are satisfied with the outcome of the transaction, they have to confirm the transaction as complete. The payment is then released to the vendor and the security deposits are refunded to both parties at no fee.

Particl’s MAD escrow system renders the marketplace fully fungible. That's because all transactions are untraceable by default. In fact, not only is all marketplace content encrypted, but all currency transactions are made untraceable through the use of theConfidential Transactions (CT) privacy protocol.

This is achieved by making the MAD escrow smart-contract exclusively work with CT and forcing all transactions to have to go through it. This technique enhances privacy much more than if CT MAD escrow was optional because it increases the number of privacy transactions on the network.

Another privacy-enhancing aspect of the MAD escrow mechanism is its lack of third-party acting as escrow agent. In fact, in most centralized escrow system, conversations between the buyer and the seller are available to the escrow agent. This is so the escrow agent can step in if any problem arises and issue a resolution based on the context. This puts a lot of power into the agent's hands and assumes it is acting in an honest way.

By not requiring any third-party, the Open Marketplace's escrow system preserves the privacy of both parties. Any transaction detail or conversation is only available to the transacting parties and no one else. Particl's decentralized escrow system will use RingCT instead of CT once it hits mainnet

This form of decentralized escrow is infinitely scalable. It doesn't need any other party other than the ones transacting to function. Escrow transactions can be opened as required by the users. No staff is required, no data can be mined, and no delay can be caused by outside parties. The Particl network can support an infinite number of escrow deals at the same time.

As a fully decentralized solution, Particl's Open Marketplace doesn't rely on hired moderators to keep its content clean. It is instead governed by its community of holders rather than a team of staff or a third-parties. Since it is fully anonymous, it is not unlikely that undesirable items and services would be listed for sale. This is why there has to be a way to moderate the marketplace. This ensures the marketplace preserves its legitimacy and that it doesn't become an enabler of immoral businesses and activities. Having a third-party as moderator introduces a whole lot of issues such as legal liability, centralization of power and decision making, lack of scalability, and friction.

Particl’s way to deal with this problem is to allow its own community of users to be the moderators. In fact, all listings can be flagged by any user. Votes are tallied based on coin weight where one coin equals one vote. The more coins a user holds, the more influence he has over the outcome of a flagging vote.

Once a certain weight threshold is reached (temporarily set at 9,000 coins for the time being), the listing is taken out of the marketplace. This also applies to private listings even though they do not appear on the public interface of the marketplace. Anyone with access to a private market can flag its listings, although it may prove much more difficult to reach the threshold.

Data Storage Networks (DSN) are used on Particl to store any data (i.e. marketplace-related data such as images) off-chain. Contrary to on-chain storage, this allows the platform to scale well regardless of the amount of data it uses. This form of storage works without relying on servers and without centralizing powers into masternodes. The default (and for the moment, the only) DSN used on Particl is SMSG. It is a P2P BitMessage-like message mixnet that runs parallel to Particl's blockchain. It is hosted on the same nodes that run the Particl blockchain.

A small hash of the hosted content is created and stored on the Particl blockchain when it is used to store data on a DSN. To verify the integrity of data when the client retrieves it back from the DSN, its hash is recomputed and compared with the one stored on the Particl blockchain. The data is considered trusted if the hashes match, and rejected by the platform if they don’t.

SecureMessaging (SMSG), the DSN used to store data off-chain, is also used as the messaging protocol for the marketplace. It is a decentralized P2P message mixnet where all nodes store a copy of everyone's end-to-end encrypted messages and data for a duration of 48 hours (which can be increased for a fee). It is the default and most private DSN available for use on the platform. The reference implementation is developed in C++ and incorporated into the Particl daemon. It operates parallel to Particl's network and is hosted on the same nodes running the blockchain.

All nodes continuously attempt to decrypt every incoming message, but can only succeed if the node is able to recalculate the HMAC hash accompanying the message. If the hash check fails, then it can not be decrypted by the node, which means the message was either fraudulent, tampered with or meant for another node. SMSG messages are stripped from of any metadata, therefore it is impossible for anyone to extract information such as IP addresses, sender or receiver. The only metadata not stripped from SMSG messages are the hash, the encryption payload, and a temporary public key.

The first mainnet version of Particl's Open Marketplace will not contain any messaging option. This functionality will be added during the Beta stage of development as one of the Release Candidates.

The Open Marketplace is designed so buyers aren't limited to using the PART coin as a form of payment. They are able to use many currencies, including Bitcoin, among others. This provides a use-case for many different coins and gives them a fee-less and untraceable way to spend their cryptocurrencies without having to either go through a third-party or sell their coins for fiat on exchanges.

It's important to note that, even though many coins can be used as a form of payment, all non-PART transactions are automatically converted into PART transactions by the marketplace. This is because the escrow smart-contract needs to use PART in order to operate. The PART coin is also required for the escrow mechanism to execute transactions anonymously (it uses PART's CT and RingCT privacy protocols). The integration of other coins can be achieved in two ways: atomic swaps and third party integration.

For simplicity, we assume the initiator of atomic swaps wishes to trade Particl for Decred with the participant. The initiator can also trade Decred for Particl and the steps will be the same, but with each step performed on the other blockchain. At this point, the participant is unable to claim the funds from the initiator's Particl smart contract because the secret key is unknown by them. If the initiator revealed their secret key at this moment, the participant could claim the funds from the contract without ever honoring their end of the trade, leaving the initiator at a loss.

To avoid this, the participant creates a similar smart-contract but on the Decred blockchain and sends the intended Decred amount into it. However, for the initiator to redeem the output, their own secret key must be revealed to the participant. For the participant to create their smart-contract, the initiator must reveal not the secret key (since the participant could still claim funds and not honor their end of the deal), but a cryptographic hash of the secret key to the participant so that the smart-contract can be properly deployed.

The participant's contract can equally be refunded after a pre-determined period of time.The initiator then redeems the participant's Decred funds by revealing the secret key to the participant’s smart-contract. The secret key is then extracted from the initiator's redeeming Decred transaction providing the participant with the ability to redeem the initiator's Particl contract.

This procedure is atomic (with timeout) as it gives each party a set period of time to redeem their coins on the other blockchain before a refund can be performed. This is the best option for people requiring privacy, and is also probably going to be the cheapest to use.

Using the modular Particl Desktop wallet, third-parties can be integrated to enhance the user experience and provide optional services. An example is the integration of non-custodial exchanges such as Changelly, Shapeshift, or Altcoin.io.

While not as private and cheap as atomic swaps, third-party services do offer some benefits. Liquidity and volume, at this point in time, can be much better on centralized exchanges. Some of these services (i.e. Changelly, Indacoin) also offer fiat options and pairs. This would allow the Open Marketplace to offer in-wallet fiat payment options.

Particl will always prioritize decentralized solutions over ones that introduce third-parties. However, payment options need to have volume and liquidity for them to be efficient and cost-effective for the user.The first mainnet version of Particl's Open Marketplace will only work using the PART coin. Alternative payment options will be added during the Beta stage of development as one of the Release Candidates.

Particl's Open Marketplace is run collectively by its users, there is no operational cost associated with it. There is also no company looking into making profits out of its operation. This allows the marketplace to charge the bare minimum for it to operate.

The Open Marketplace doesn't charge its buyers with any fee, except for the usual cryptocurrency transaction fee. Its vendors, on the other hand, are only charged with a very small listing fee amounting to only a few cents per item. This is only designed to fight off spam listings and keep the interface clean.

Particl Desktop is the client used to access the Open Marketplace. It is a modern and very user-friendly client which acts as the gateway into Particl's decentralized economy. Particl Desktop aims at making the Open Marketplace as easy to use as any other marketplace on the web or any other software. It is built using Angular and Electron and is modular in nature, meaning it can easily be customized to add functionalities.