Since on the Bitcoin blockchain we only publish a commitment of an ownership transfer, not the content of the transfer itself, the seller needs a dedicated communication channel to provide the buyer with all the proofs that the ownership transfer is valid. This could be done in a number of ways, potentially even by printing out the proofs and shipping them with a carrier pigeon, which, while a bit impractical, would still do the job. But the best option to avoid the censorship and privacy violations is establish a direct peer-to-peer encrypted communication, which compared to the pigeons also has the advantage of being easy to integrate with a software to verify the proofs received from the counterparty.
This model just described for client-side validated contracts and ownership transfers is exactly what has been implemented with the RGB protocol. With RGB, it is possible to create a contract that defines rights, assigns them to one or more existing bitcoin UTXO and specifies how their ownership can be transferred. The contract can be created starting from a template, called a “schema,” in which the creator of the contract only adjusts the parameters and ownership rights, as is done with traditional legal contracts. Currently, there are two types of schemas in RGB: one for issuing fungible tokens (
RGB20) and a second for issuing collectibles (RGB21), but in the future, more schemas can be developed by anyone in a permissionless fashion without requiring changes at the protocol level.
To use a more practical example, an issuer of fungible assets (e.g. company shares, stablecoins, etc.) can use the RGB20 schema template and create a contract defining how many tokens it will issue, the name of the asset and some additional metadata associated with it. It can then define which bitcoin UTXO has the right to transfer ownership of the created tokens and assign other rights to other UTXOs, such as the right to make a secondary issuance or to renominate the asset. Each client receiving tokens created by this contract will be able to verify the content of the Genesis contract and validate that any transfer of ownership in the history of the token received has complied with the rules set out therein.
So what can we do with RGB in practice today? First and foremost, it enables the issuance and the transfer of tokenized assets with better scalability and privacy compared to any existing alternative. On the privacy side, RGB benefits from the fact that all transfer-related data is kept client-side, so a blockchain observer cannot extract any information about the user’s financial activities (it is not even possible to distinguish a bitcoin transaction containing an RGB commitment from a regular one), moreover, the receiver shares with the sender only blinded UTXO (i. e. the hash of the concatenation between the UTXO in which she wish to receive the assets and a random number) instead of the UTXO itself, so it is not possible for the payer to monitor future activities of the receiver. To further increase the privacy of users, RGB also adopts the bulletproof cryptographic mechanism to hide the amounts in the history of asset transfers, so that even future owners of assets have an obfuscated view of the financial behavior of previous holders.
In terms of scalability, RGB offers some advantages as well. First of all, most of the data is kept off-chain, as the blockchain is only used as a commitment layer, reducing the fees that need to be paid and meaning that each client only validates the transfers it is interested in instead of all the activity of a global network. Since an RGB transfer still requires a Bitcoin transaction, the fee saving may seem minimal, but when you start introducing transaction batching they can quickly become massive. Indeed, it is possible to transfer all the tokens (or, more generally, “rights”) associated with a UTXO towards an arbitrary amount of recipients with a single commitment in a single bitcoin transaction. Let’s assume you are a service provider making payouts to several users at once. With RGB, you can commit in a single Bitcoin transaction thousands of transfers to thousands of users requesting different types of assets, making the marginal cost of each single payout absolutely negligible.
Another fee-saving mechanism for issuers of low value assets is that in RGB the issuance of an asset does not require paying fees. This happens because the creation of an issuance contract does not need to be committed on the blockchain. A contract simply defines to which already existing UTXO the newly issued assets will be allocated to. So if you are an artist interested in creating collectible tokens, you can issue as many as you want for free and then only pay the bitcoin transaction fee when a buyer shows up and requests the token to be assigned to their UTXO.
Furthermore, because RGB is built on top of bitcoin transactions, it is also compatible with the Lightning Network. While it is not yet implemented at the time of writing, it will be possible to create asset-specific Lightning channels and route payments through them, similar to how it works with normal Lightning transactions.
RGB is a groundbreaking innovation that opens up to new use cases using a completely new paradigm, but which tools are available to use it? If you want to experiment with the core of the technology itself, you should directly try out the
RGB node. If you want to build applications on top of RGB without having to deep dive into the complexity of the protocol, you can use the rgb-lib library, which provides a simple interface for developers. If you just want to try to issue and transfer assets, you can play with Iris Wallet for Android, whose code is also open source on GitHub. If you just want to learn more about RGB you can check out this list of resources.
This is a guest post by Federico Tenga. Opinions expressed are entirely their own and do not necessarily reflect those of BTC Inc or Bitcoin Magazine.