The CMTA token (CMTAT) is a framework enabling the tokenization of securities in compliance with Swiss law.
The CMTAT is an open standard from the Capital Markets and Technology Association (CMTA), and the product of collaborative work by leading organizations in the Swiss finance and technology ecosystem.
The present repository provides CMTA's reference implementation of CMTAT for Ethereum, as an ERC-20 compatible token.
The CMTAT is developed by a working group of CMTA's Technical Committee that includes members from Atpar, Bitcoin Suisse, Blockchain Innovation Group, Hypothekarbank Lenzburg, Lenz & Staehelin, Metaco, Mt Pelerin, SEBA, Swissquote, Sygnum, Taurus and Tezos Foundation. The design and security of the CMTAT was supported by ABDK, a leading team in smart contract security.
The preferred way to receive comments is through the GitHub issue tracker. Private comments and questions can be sent to the CMTA secretariat at admin@cmta.ch.
The CMTAT supports the following core features:
- Basic mint, burn, and transfer operations
- Pause of the contract and freeze of specific accounts
Furthermore, the present implementation uses standard mechanisms in order to support:
- Distribution of dividends and interest, via snapshots
- Upgradeability, via deployment of the token with a proxy
- "Gasless" transactions
- Conditional transfers, via a rule engine
This reference implementation allows the issuance and management of tokens representing equity securities. It can however also be used for other forms of financial instruments such as debt securities.
To use the CMTAT, we recommend that you use the latest audited version, from the Releases page.
You may modify the token code by adding, removing, or modifying features. However, the base, enforcement, and snapshot modules must remain in place for compliance with Swiss law.
The CMTAT supports deployment via a proxy contract. Furthermore, using a proxy permits to upgrade the contract, using a standard proxy upgrade pattern.
At deployment, the parameter deployedWithProxyIrrevocable_ inside the CMTAT contract constructor has to be set at true
Please see the OpenZeppelin upgradeable contracts documentation for more information about the proxy requirements applied to the contract.
Please see the OpenZeppelin Upgrades plugins for more information about upgrades plugins in general.
Note that deployment via a proxy is not mandatory, but recommended by CMTA.
The CMTAT supports client-side gasless transactions using the Gas
Station Network (GSN) pattern, the main open standard for transfering fee payment to another account than that of the transaction issuer. The contract uses the OpenZeppelin contract ERC2771ContextUpgradeable, which allows a contract to get the original client with _msgSender() instead of the fee payer given by msg.sender while allowing upgrades on the main contract (see Deployment via a proxy above).
At deployment, the parameter forwarder inside the CMTAT contract constructor has to be set with the defined address of the forwarder. Please note that the forwarder can not be changed after deployment, and with a proxy architecture, its value is stored inside the implementation contract bytecode instead of the storage of the proxy.
Please see the OpenGSNdocumentation for more details on what is done to support GSN in the contract.
A "kill switch" is a necessary function to allow the issuer to carry out certain corporate actions (e.g., share splits, reverse splits, and mergers), which involve cancelling all existing tokens and replacing them by new ones, and can also be used if the issuer decides that it no longer wishes to have its shares issued in the form of ledger securities. The "kill switch" function affects all tokens issued.
Such a functionality can be performed via that kill() function. A new token contract may then be deployed via the proxy.
Alternatively, if interactions with the "killed contract" are still necessary, it may be paused (and never unpaused).
The contracts have been audited by ABDKConsulting, a globally recognized firm specialized in smart contracts' security.
Fixes of security issues discovered by the initial audit were reviewed by ABDK and confirmed to be effective, as certified by the report released on September 10, 2021], covering version c3afd7b of the contracts. Version 1.0 includes additional fixes of minor issues, compared to the version retested.
As with any token contract, access to the owner key must be adequately restricted. Likewise, access to the proxy contract must be restricted and seggregated from the token contract.
Please see the doc/modules for documentation of the modules API.
CMTA will release further documentation describing the CMTAT framework in a platform-agnostic way, and coveging legal aspects.
The code is copyright (c) Capital Market and Technology Association, 2018-2023, and is released under Mozilla Public License 2.0.