The Polymath Core smart contracts provide a system for launching regulatory-compliant securities tokens on a decentralized blockchain. This particular repository is the implementation of a system that allows for the creation of ST-20-compatible tokens. This system has a modular design that promotes a variety of pluggable components for various types of issuances, legal requirements, and offering processes.
An ST-20 token is an Ethereum-based token implemented on top of the ERC-20 protocol that adds the ability for tokens to control transfers based on specific rules. ST-20 tokens rely on Transfer Managers to determine the ruleset the token should apply in order to allow or deny a transfer, be it between the issuer and investors, in a peer to peer exchange, or a transaction with an exchange.
ST-20 tokens must implement a verifyTransfer method which will be called when attempting to execute a transfer or transferFrom method. The verifyTransfer method will determine whether that transaction can be completed or not. The implementation of verifyTransfer can take many forms, but the default approach is a whitelist controlled by the GeneralTransferManager.
contract IST20 {
// off-chain hash
bytes32 public tokenDetails;
//transfer, transferFrom must respect the result of verifyTransfer
function verifyTransfer(address _from, address _to, uint256 _amount) view public returns (bool success);
//used to create tokens
function mint(address _investor, uint256 _amount) public returns (bool success);
}
The diagram below depicts a high-level view of the various modules, registries, and contracts implemented in Polymath Core:
SecurityToken is an implementation of the ST-20 protocol that allows the addition of different modules to control its behavior. Different modules can be attached to SecurityToken:
- TransferManager modules: These control the logic behind transfers and how they are allowed or disallowed. By default, the ST (Security Token) gets a GeneralTransferManager module attached in order to determine if transfers should be allowed based on a whitelist approach. The GeneralTransferManager behaves differently depending who is trying to transfer the tokens. a) In an offering setting (investors buying tokens from the issuer) the investor's address should be present on an internal whitelist managed by the issuer within the GeneralTransferManager. b) In a peer to peer transfer, restrictions apply based on real-life lockups that are enforced on-chain. For example, if a particular holder has a 1-year sale restriction for the token, the transaction will fail until that year passes.
- Security Token Offering (STO) modules: A SecurityToken can be attached to one (and only one) STO module that will dictate the logic of how those tokens will be sold/distributed. An STO is the equivalent to the Crowdsale contracts often found present in traditional ICOs.
- Permission Manager modules: These modules manage permissions on different aspects of the issuance process. The issuer can use this module to manage permissions and designate administrators on his token. For example, the issuer might give a KYC firm permissions to add investors to the whitelist.
The ticker registry manages the sign up process to the Polymath platform. Issuers can use this contract to register a token symbol (which are unique within the Polymath network). Token Symbol registrations have an expiration period (7 days by default) in which the issuer has to complete the process of deploying their SecurityToken. If they do not complete the process in time, their ticker symbol will be made available for someone else to register.
The security token registry keeps track of deployed STs on the Polymath Platform and uses the TickerRegistry to allow only registered symbols to be deployed.
Modules allow custom add-in functionality in the issuance process and beyond. The module registry keeps track of modules added by Polymath or any other users. Modules can only be attached to STs if Polymath has previously verified them. If not, the only user able to utilize a module is its owner, and they should be using it "at their own risk".
First, assure that you have setup Polymath Core properly.
The CLI (Command Line Interface) ST-20 Generator tool is a wizard-like script that will guide technical users in the creation and deployment of an ST-20 token. The commands are operated from a *nix command prompt (unix or mac).
To use it, make sure you are connected to a full ethereum node (or locally to Ganache-cli, a local private test network).
You can run Parity with the following command to get started (make sure the node is fully synced before using the CLI tool):
parity --chain ropsten --rpcapi "eth,net,web3,personal,parity" --unlock YOUR_ETH_ACCOUNT --password $HOME/password.file
- Edit
demo/helpers/contract_addresses.jsto make sure scripts are pointing to the correct contract addresses - On the terminal, run the following command:
npm run st20Generator - Follow the text prompts:
- You will be asked for a token symbol. Enter a new symbol to register or a symbol you have already registered.
- Enter a token name (long name seen by investors) to complete the token registration process. The token will be deployed to the blockchain.
- (Optional) If you want to issue tokens to an address you own, enter the address and then how many tokens you want to issue.
- Configure the Capped STO. Enter start and end times, the issuance cap, and exchange rate.
- Once the process is finished, you can run the
npm run st20generatorcommand again and enter the token symbol to see the STO's live-progress.
After starting the STO you can run a whitelist script to mass-update a whitelist of allowed/known investors.
Make sure the whitelist_data.csv file is present in the demo folder.
node demo/whitelist TOKEN_SYMBOL
You can run the invest script to participate in any STO you have been whitelisted for. The script takes 3 parameters:
- The token symbol for the STO you want to invest in
- The account that will receive the tokens
- How much ETH to send
node demo/invest TOKEN_SYMBOL BENEFICIARY ETHER
You can run the transfer script to transfer ST tokens to another account (as long as both are whitelisted and have been cleared of any lockup periods).
- The token symbol of the ST you want to transfer
- The account that will receive the tokens
- How many tokens to send
node demo/transfer TOKEN_SYMBOL ACCOUNT_TO AMOUNT
| Contract | Address |
|---|---|
| TickerRegistry: | 0x0abeafae9333f7dc64959914f67765edee5fd05f |
| SecurityTokenRegistry: | 0x8e736d9caeb9eb9b7a766c196fbb01eb53344e81 |
| ModuleRegistry: | 0x850bfedbf6c957fd195e4f555c7deab6cd226a5a |
| CappedSTOFactory: | 0x423105526255dB03C36FD763C982daD96B95D17e |
The smart contracts are written in [Solidity][solidity] and tested/deployed using [Truffle][truffle] version 4.1.0. The new version of Truffle doesn't require testrpc to be installed separately so you can just run the following:
# Install Truffle package globally:
$ npm install -g truffle
# Install local node dependencies:
$ npm installTo test the code simply run:
$ npm run test
-
Deploy ModuleRegistry. ModuleRegistry keeps track of all available modules that add new functionalities to Polymath-based security tokens.
-
Deploy GeneralTransferManagerFactory. This module allows the use of a general TransferManager for newly issued security tokens. The General Transfer Manager gives STs the ability to have their transfers restricted by using an on-chain whitelist.
-
Add the GeneralTransferManagerFactory module to ModuleRegistry by calling
ModuleRegistry.registerModule(). -
Deploy TickerRegistry. This contract handles the registration of unique token symbols. Issuers first have to claim their token symbol through the TickerRegistry. If it's available they will be able to deploy a ST with the same symbol for a set number of days before the registration expires.
-
Deploy SecurityTokenRegistry. This contract is responsible for deploying new Security Tokens. STs should always be deployed by using the SecurityTokenRegistry.
Security Token Offerings (STOs) grant STs the ability to be distributed in an initial offering. Polymath offers a few out-of-the-box STO models for issuers to select from and, as the platform evolves, 3rd party developers will be able to create their own offerings and make them available to the network.
As an example, we've included a CappedSTO and CappedSTOFactory contracts.
In order to create a new STO, developers first have to create an STO Factory contract which will be responsible for instantiating STOs as Issuers select them. Each STO Factory has an STO contract attached to it, which will be instantiated for each Security Token that wants to use that particular STO.
To make an STO available for Issuers, first, deploy the STO Factory and take note of its address. Then, call moduleRegistry.registerModule(STO Factory address);
Once the STO Factory has been registered to the Module Registry, issuers will be able to see it on the Polymath dApp and they will be able to add it as a module of the ST.
Note that while anyone can register an STO Factory, only those "approved" by Polymath will be enabled to be attached by the general community. An STO Factory not yet approved by Polymath may only be used by it's author.
The polymath-core repo follows the style guide overviewed here: http://solidity.readthedocs.io/en/develop/style-guide.html