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Abstract​

This document specifies the internal x/erc20 module of the Cosmos EVM. The x/erc20 module enables the Cosmos EVM to support a trustless, on-chain bidirectional internal conversion of tokens between the EVM and Cosmos runtimes, specifically the x/vm and x/bank modules. This allows token holders on a Cosmos EVM chain to instantaneously convert their native Cosmos sdk.Coins (in this document referred to as “Coin(s)”) to ERC-20 (aka “Token(s)”) and vice versa, while retaining fungibility with the original asset on the issuing environment/runtime (EVM or Cosmos) and preserving ownership of the ERC-20 contract. This governance functionality is implemented using the Cosmos-SDK gov module with custom proposal types for registering and updating the canonical mappings respectively. Why is this important? Cosmos and the EVM are two runtimes that are not compatible by default. The native Cosmos Coins cannot be used in applications that require the ERC-20 standard. Cosmos coins are held on the x/bank module (with access to module methods like querying the supply or balances) and ERC-20 Tokens live on smart contracts. This problem is similar to wETH, with the difference, that it not only applies to gas tokens, but to all Cosmos Coins (IBC vouchers, staking and gov coins, etc.) as well. With the x/erc20 users of a Cosmos EVM chain can
  • use existing native cosmos assets (like OSMO or ATOM) on EVM-based chains, e.g. for Trading IBC tokens on DeFi protocols, buying NFT, etc.
  • transfer existing tokens on Ethereum and other EVM-based chains to a Cosmos EVM chain to take advantage of application-specific chains in the IBC Network
  • build new applications that are based on ERC-20 smart contracts and have access to the IBC Network.

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Contents​

  1. Concepts
  2. State
  3. State Transitions
  4. Transactions
  5. Hooks
  6. Events
  7. Parameters
  8. Clients

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Concepts​

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Token Pair​

The x/erc20 module maintains a canonical one-to-one mapping of native Cosmos Coin denomination to ERC20 Token contract addresses (i.e sdk.Coin ←→ ERC20), called TokenPair. The conversion of the ERC20 tokens ←→ Coin of a given pair can be enabled or disabled via governance.

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Token Pair Registration​

Users can register a new token pair proposal through the governance module and initiate a vote to include the token pair in the module. Depending on which exists first, the coin or the token, you can either register a Cosmos Coin or a ERC20 Token to create a token pair. One proposal can inculde several token pairs. When the proposal passes, the erc20 module registers the Cosmos Coin and ERC20 Token mapping on the application’s store.

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Registration of a Cosmos Coin​

A native Cosmos Coin corresponds to an sdk.Coin that is native to the bank module. It can be either the native staking/gas denomination (e.g. ATOM, etc) or an IBC fungible token voucher (i.e. with denom format of ibc/{hash}). When a proposal is initiated for an existing native Cosmos Coin, the erc20 module will deploy a factory ERC20 contract, representing the ERC20 token for the token pair, giving the module ownership of that contract.

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Registration of an ERC20 token​

A proposal for an existing (i.e already deployed) ERC20 contract can be initiated too. In this case, the ERC20 maintains the original owner of the contract and uses an escrow & mint / burn & un-escrow mechanism similar to the one defined by the ICS20 - Fungible Token Transfer specification. The token pair is composed of the original ERC20 token and a corresponding native Cosmos coin denomination.

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Token details and metadata​

Coin metadata is derived from the ERC20 token details (name, symbol, decimals) and vice versa. A special case is also described below that for the ERC20 representation of IBC fungible token (ICS20) vouchers.

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Coin Metadata to ERC20 details​

During the registration of a Cosmos Coin the following bank Metadata is used to deploy a ERC20 contract:
  • Name
  • Symbol
  • Decimals
The native Cosmos Coin contains a more extensive metadata than the ERC20 and includes all necessary details for the conversion into a ERC20 Token, which requires no additional population of data.

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IBC voucher Metadata to ERC20 details​

IBC vouchers should comply to the following standard:
  • Name: {NAME} channel-{channel}
  • Symbol: ibc{NAME}-{channel}
  • Decimals: derived from bank Metadata

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ERC20 details to Coin Metadata​

During the Registration of an ERC20 Token the Coin metadata is derived from the ERC20 metadata and the bank metadata:
  • Description: Cosmos coin token representation of {contractAddress}
  • DenomUnits:
    • Coin: 0
    • ERC20: {uint32(erc20Data.Decimals)}
  • Base: {"erc20/%s", address}
  • Display: {erc20Data.Name}
  • Name: {types.CreateDenom(strContract)}
  • Symbol: {erc20Data.Symbol}

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Token Pair Modifiers​

A valid token pair can be modified through several governance proposals. The internal conversion of a token pair can be toggled with ToggleTokenConversionProposal, so that the conversions between the token pair’s tokens can be enabled or disabled.

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Token Conversion​

Once a token pair proposal passes, the module allows for the conversion of that token pair. Holders of native Cosmos coins and IBC vouchers on a Cosmos EVM chain can convert their Coin into ERC20 Tokens, which can then be used on the EVM chain, by creating a ConvertCoin Tx. Vice versa, the ConvertERC20 Tx allows holders of ERC20 tokens on the Cosmos EVM chain to convert ERC-20 tokens back to their native Cosmos Coin representation. Depending on the ownership of the ERC20 contract, the ERC20 tokens either follow a burn/mint or a transfer/escrow mechanism during conversion.

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Malicious Contracts​

The ERC20 standard is an interface that defines a set of method signatures (name, arguments and output) without defining its methods’ internal logic. Therefore it is possible for developers to deploy contracts that contain hidden malicious behaviour within those methods. For instance, the ERC20 transfer method, which is responsible for sending an amount of tokens to a given recipient could include code to siphon some amount of tokens intended for the recipient into a different predefined account, which is owned by the malicious contract deployer. More sophisticated malicious implementations might also inherit code from customized ERC20 contracts that include malicous behaviour. For an overview of more extensive examples, please review the x/erc20 audit, section IF-EVMOS-06: IERC20 Contracts may execute arbitrary code. As the x/erc20 module allows any arbitrary ERC20 contract to be registered through governance, it is essential that the proposer or the voters manually verify during voting phase that the proposed contract uses the default ERC20.sol implementation. Here are our recommendations for the reviewing process:
  • contract solidity code should be verified and accessable (e.g. using an explorer)
  • contract should be audited by a reputabele auditor
  • inherited contracts need to be verified for correctness

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State​

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State Objects​

The x/erc20 module keeps the following objects in state:
State ObjectDescriptionKeyValueStore
TokenPairToken Pair bytecode[]byte{1} + []byte(id)[]byte{tokenPair}KV
TokenPairByERC20Token Pair id bytecode by erc20 contract bytes[]byte{2} + []byte(erc20)[]byte(id)KV
TokenPairByDenomToken Pair id bytecode by denom string[]byte{3} + []byte(denom)[]byte(id)KV

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Token Pair​

One-to-one mapping of native Cosmos coin denomination to ERC20 token contract addresses (i.e sdk.Coin ←→ ERC20). 
type TokenPair struct { // address of ERC20 contract token Erc20Address string `protobuf:"bytes,1,opt,name=erc20_address,json=erc20Address,proto3" json:"erc20_address,omitempty"` // cosmos base denomination to be mapped to Denom string `protobuf:"bytes,2,opt,name=denom,proto3" json:"denom,omitempty"` // shows token mapping enable status Enabled bool `protobuf:"varint,3,opt,name=enabled,proto3" json:"enabled,omitempty"` // ERC20 owner address ENUM (0 invalid, 1 ModuleAccount, 2 external address ContractOwner Owner `protobuf:"varint,4,opt,name=contract_owner,json=contractOwner,proto3,enum=cosmos.evm.erc20.v1.Owner" json:"contract_owner,omitempty"`}

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Token pair ID​

The unique identifier of a TokenPair is obtained by obtaining the SHA256 hash of the ERC20 hex contract address and the Coin denomination using the following function: 
tokenPairId = sha256(erc20 + "|" + denom)

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Token Origin​

The ConvertCoin and ConvertERC20 functionalities use the owner field to check whether the token being used is a native Coin or a native ERC20. The field is based on the token registration proposal type (RegisterCoinProposal = 1, RegisterERC20Proposal = 2). The Owner enumerates the ownership of a ERC20 contract. 
type Owner int32const ( // OWNER_UNSPECIFIED defines an invalid/undefined owner. OWNER_UNSPECIFIED Owner = 0 // OWNER_MODULE erc20 is owned by the erc20 module account. OWNER_MODULE Owner = 1 // EXTERNAL erc20 is owned by an external account. OWNER_EXTERNAL Owner = 2)
The Owner can be checked with the following helper functions: 
// IsNativeCoin returns true if the owner of the ERC20 contract is the// erc20 module accountfunc (tp TokenPair) IsNativeCoin() bool { return tp.ContractOwner == OWNER_MODULE}// IsNativeERC20 returns true if the owner of the ERC20 contract not the// erc20 module accountfunc (tp TokenPair) IsNativeERC20() bool { return tp.ContractOwner == OWNER_EXTERNAL}

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Token Pair by ERC20 and by Denom​

TokenPairByERC20 and TokenPairByDenom are additional state objects for querying a token pair id.

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Genesis State​

The x/erc20 module’s GenesisState defines the state necessary for initializing the chain from a previous exported height. It contains the module parameters and the registered token pairs : 
// GenesisState defines the module's genesis state.type GenesisState struct { // module parameters Params Params `protobuf:"bytes,1,opt,name=params,proto3" json:"params"` // registered token pairs TokenPairs []TokenPair `protobuf:"bytes,2,rep,name=token_pairs,json=tokenPairs,proto3" json:"token_pairs"`}

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State Transitions​

The erc20 modules allows for two types of registration state transitions. Depending on how token pairs are registered, with RegisterCoinProposal or RegisterERC20Proposal, there are four possible conversion state transitions.

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Token Pair Registration​

Both the Cosmos coin and the ERC20 token registration allow for registering several token pairs with one proposal. For simplicity, the following description describes the registration of only one token pair per proposal.

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1. Register Coin​

A user registers a native Cosmos Coin. Once the proposal passes (i.e is approved by governance), the ERC20 module uses a factory pattern to deploy an ERC20 token contract representation of the Cosmos Coin. Note that the native chain’s coin cannot be registered, as any coin including “evm” in its denomination cannot be registered. Instead, the chain’s token can be converted by wrapping it in a contract.
  1. User submits a RegisterCoinProposal
  2. The chain’s validators vote on the proposal using MsgVote and proposal passes
  3. If Cosmos coin or IBC voucher exist on the bank module supply, create the ERC20 token contract on the EVM based on the ERC20Mintable (ERC20Mintable by openzeppelin) interface
    • Initial supply: 0
    • Token details (Name, Symbol, Decimals, etc) are derived from the bank module Metadata field on the proposal content.

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2. Register ERC20​

A user registers a ERC20 token contract that is already deployed on the EVM module. Once the proposal passes (i.e. is approved by governance), the ERC20 module creates a Cosmos coin representation of the ERC20 token.
  1. User submits a RegisterERC20Proposal
  2. The chain’s validators vote on the proposal using MsgVote and proposal passes
  3. If ERC-20 contract is deployed on the EVM module, create a bank coin Metadata from the ERC20 details.

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Token Pair Conversion​

Conversion of a registered TokenPair can be done via:
  • Cosmos transaction (ConvertCoin and ConvertERC20)
  • Ethereum transaction (i.e sending a MsgEthereumTx that leverages the EVM hook)

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1. Registered Coin​

Context: A TokenPair has been created through a RegisterCoinProposal governance proposal. The proposal created an ERC20 contract (ERC20Mintable by openzeppelin) of the ERC20 token representation of the Coin from the ModuleAccount, assigning it as the owner of the contract and thus granting it the permission to call the mint() and burnFrom() methods of the ERC20.
Invariants​
  • Only the ModuleAccount should have the Minter Role on the ERC20. Otherwise, the user could unilaterally mint an infinite supply of the ERC20 token and then convert them to the native Coin
  • The user and the ModuleAccount (owner) should be the only ones that have the Burn Role for a Cosmos Coin
  • There shouldn’t exist any native Cosmos Coin ERC20 Contract (eg Evmos, Atom, Osmo ERC20 contracts) that is not owned by the governance
  • Token/Coin supply is maintained at all times:
    • Total Coin supply = Coins + Escrowed Coins
    • Total Token supply = Escrowed Coins = Minted Tokens
1.1 Coin to ERC20​
  1. User submits ConvertCoin Tx
  2. Check if conversion is allowed for the pair, sender and recipient
    • global parameter is enabled
    • token pair is enabled
    • sender tokens are not vesting (checked in the bank module)
    • recipient address is not blacklisted
  3. If Coin is a native Cosmos Coin and Token Owner is ModuleAccount
    1. Escrow Cosmos coin by sending them to the erc20 module account
    2. Call mint() ERC20 tokens from the ModuleAccount address and send minted tokens to recipient address
  4. Check if token balance increased by amount
1.2 ERC20 to Coin​
  1. User submits a ConvertERC20 Tx
  2. Check if conversion is allowed for the pair, sender and recipient (see 1.1 Coin to ERC20)
  3. If token is a ERC20 and Token Owner is ModuleAccount
    1. Call burnCoins() on ERC20 to burn ERC20 tokens from the user balance
    2. Send Coins (previously escrowed, see 1.1 Coin to ERC20) from module to the recipient address.
  4. Check if
    • Coin balance increased by amount
    • Token balance decreased by amount

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2. Registered ERC20​

Context: A TokenPair has been created through a RegisterERC20Proposal governance proposal. The ModuleAccount is not the owner of the contract, so it can’t mint new tokens or burn on behalf of the user. The mechanism described below follows the same model as the ICS20 standard, by using escrow & mint / burn & unescrow logic.
Invariants​
  • ERC20 Token supply on the EVM runtime is maintained at all times:
    • Escrowed ERC20 + Minted Cosmos Coin representation of ERC20 = Burned Cosmos Coin representation of ERC20 + Unescrowed ERC20
      • Convert 10 ERC20 → Coin, the total supply increases by 10. Mint on Cosmos side, no changes on EVM
      • Convert 10 Coin → ERC20, the total supply decreases by 10. Burn on Cosmos side , no changes of supply on EVM
    • Total ERC20 token supply = Non Escrowed Tokens + Escrowed Tokens (on Module account address)
    • Total Coin supply for the native ERC20 = Escrowed ERC20 Tokens on module account (i.e balance) = Minted Coins
2.1 ERC20 to Coin​
  1. User submits a ConvertERC20 Tx
  2. Check if conversion is allowed for the pair, sender and recipient (See 1.1 Coin to ERC20)
  3. If token is a ERC20 and Token Owner is not ModuleAccount
    1. Escrow ERC20 token by sending them to the erc20 module account
    2. Mint Cosmos coins of the corresponding token pair denomination and send coins to the recipient address
  4. Check if
    • Coin balance increased by amount
    • Token balance decreased by amount
  5. Fail if unexpected Approval event found in logs to prevent malicious contract behaviour
2.2 Coin to ERC20​
  1. User submits ConvertCoin Tx
  2. Check if conversion is allowed for the pair, sender and recipient
  3. If coin is a native Cosmos coin and Token Owner is not ModuleAccount
    1. Escrow Cosmos Coins by sending them to the erc20 module account
    2. Unlock escrowed ERC20 from the module address by sending it to the recipient
    3. Burn escrowed Cosmos coins
  4. Check if token balance increased by amount
  5. Fail if unexpected Approval event found in logs to prevent malicious contract behaviour

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Transactions​

This section defines the sdk.Msg concrete types that result in the state transitions defined on the previous section.

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RegisterCoinProposal​

A gov Content type to register a token pair from a Cosmos Coin. Governance users vote on this proposal and it automatically executes the custom handler for RegisterCoinProposal when the vote passes. 
type RegisterCoinProposal struct { // title of the proposal Title string `protobuf:"bytes,1,opt,name=title,proto3" json:"title,omitempty"` // proposal description Description string `protobuf:"bytes,2,opt,name=description,proto3" json:"description,omitempty"` // metadata slice of the native Cosmos coins Metadata []types.Metadata `protobuf:"bytes,3,rep,name=metadata,proto3" json:"metadata"`}
The proposal content stateless validation fails if:
  • Title is invalid (length or char)
  • Description is invalid (length or char)
  • Metadata is invalid
    • Name and Symbol are not blank
    • Base and Display denominations are valid coin denominations
    • Base and Display denominations are present in the DenomUnit slice
    • Base denomination has exponent 0
    • Denomination units are sorted in ascending order
    • Denomination units not duplicated

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RegisterERC20Proposal​

A gov Content type to register a token pair from an ERC20 Token. Governance users vote on this proposal and it automatically executes the custom handler for RegisterERC20Proposal when the vote passes. 
type RegisterERC20Proposal struct { // title of the proposal Title string `protobuf:"bytes,1,opt,name=title,proto3" json:"title,omitempty"` // proposal description Description string `protobuf:"bytes,2,opt,name=description,proto3" json:"description,omitempty"` // contract addresses of ERC20 tokens Erc20Addresses []string `protobuf:"bytes,3,rep,name=erc20addresses,proto3" json:"erc20addresses,omitempty"`}
The proposal Content stateless validation fails if:
  • Title is invalid (length or char)
  • Description is invalid (length or char)
  • ERC20Addresses is invalid

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MsgConvertCoin​

A user broadcasts a MsgConvertCoin message to convert a Cosmos Coin to a ERC20 token. 
type MsgConvertCoin struct { // Cosmos coin which denomination is registered on erc20 bridge. // The coin amount defines the total ERC20 tokens to convert. Coin types.Coin `protobuf:"bytes,1,opt,name=coin,proto3" json:"coin"` // recipient hex address to receive ERC20 token Receiver string `protobuf:"bytes,2,opt,name=receiver,proto3" json:"receiver,omitempty"` // cosmos bech32 address from the owner of the given ERC20 tokens Sender string `protobuf:"bytes,3,opt,name=sender,proto3" json:"sender,omitempty"`}
Message stateless validation fails if:
  • Coin is invalid (invalid denom or non-positive amount)
  • Receiver hex address is invalid
  • Sender bech32 address is invalid

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MsgConvertERC20​

A user broadcasts a MsgConvertERC20 message to convert a ERC20 token to a native Cosmos coin. 
type MsgConvertERC20 struct { // ERC20 token contract address registered on erc20 bridge ContractAddress string `protobuf:"bytes,1,opt,name=contract_address,json=contractAddress,proto3" json:"contract_address,omitempty"` // amount of ERC20 tokens to mint Amount github_com_cosmos_cosmos_sdk_types.Int `protobuf:"bytes,2,opt,name=amount,proto3,customtype=github.com/cosmos/cosmos-sdk/types.Int" json:"amount"` // bech32 address to receive SDK coins. Receiver string `protobuf:"bytes,3,opt,name=receiver,proto3" json:"receiver,omitempty"` // sender hex address from the owner of the given ERC20 tokens Sender string `protobuf:"bytes,4,opt,name=sender,proto3" json:"sender,omitempty"`}
Message stateless validation fails if:
  • Contract address is invalid
  • Amount is not positive
  • Receiver bech32 address is invalid
  • Sender hex address is invalid

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ToggleTokenConversionProposal​

A gov Content type to toggle the internal conversion of a token pair. 
type ToggleTokenConversionProposal struct { // title of the proposal Title string `protobuf:"bytes,1,opt,name=title,proto3" json:"title,omitempty"` // proposal description Description string `protobuf:"bytes,2,opt,name=description,proto3" json:"description,omitempty"` // token identifier can be either the hex contract address of the ERC20 or the // Cosmos base denomination Token string `protobuf:"bytes,3,opt,name=token,proto3" json:"token,omitempty"`}

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Hooks​

The erc20 module implements transaction hooks from the EVM in order to trigger token pair conversion.

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EVM Hooks​

The EVM hooks allows users to convert ERC20s to Cosmos Coins by sending an Ethereum tx transfer to the module account address. This enables native conversion of tokens via Metamask and EVM-enabled wallets for both token pairs that have been registered through a native Cosmos coin or an ERC20 token. Note that additional coin/token balance checks for sender and receiver to prevent malicious contract behaviour (as performed in the ConvertERC20 msg) cannot be done here, as the balance prior to the transaction is not available in the hook.

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Registered Coin: ERC20 to Coin​

  1. User transfers ERC20 tokens to the ModuleAccount address to escrow them
  2. Check if the ERC20 Token that was transferred from the sender is a native ERC20 or a native Cosmos Coin by looking at the Ethereum event logs
  3. If the token contract address corresponds to the ERC20 representation of a native Cosmos Coin
    1. Call burn() ERC20 method from the ModuleAccount. Note that this is the same as 1.2, but since the tokens are already on the ModuleAccount balance, we burn the tokens from the module address instead of calling burnFrom(). Also note that we don’t need to mint because 1.1 coin to erc20 escrows the coin
    2. Transfer Cosmos Coin to the bech32 account address of the sender hex address

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Registered ERC20: ERC20 to Coin​

  1. User transfers coins to theModuleAccount to escrow them
  2. Check if the ERC20 Token that was transferred is a native ERC20 or a native cosmos coin
  3. If the token contract address is a native ERC20 token
    1. Mint Cosmos Coin
    2. Transfer Cosmos Coin to the bech32 account address of the sender hex

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Events​

The x/erc20 module emits the following events:

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Register Coin Proposal​

TypeAttribute KeyAttribute Value
register_coin"cosmos_coin"{denom}
register_coin"erc20_token"{erc20_address}

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Register ERC20 Proposal​

TypeAttribute KeyAttribute Value
register_erc20"cosmos_coin"{denom}
register_erc20"erc20_token"{erc20_address}

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Toggle Token Conversion​

TypeAttribute KeyAttribute Value
toggle_token_conversion"erc20_token"{erc20_address}
toggle_token_conversion"cosmos_coin"{denom}

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Convert Coin​

TypeAttribute KeyAttribute Value
convert_coin"sender"{msg.Sender}
convert_coin"receiver"{msg.Receiver}
convert_coin"amount"{msg.Coin.Amount.String()}
convert_coin"cosmos_coin"{denom}
convert_coin"erc20_token"{erc20_address}

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Convert ERC20​

TypeAttribute KeyAttribute Value
convert_erc20"sender"{msg.Sender}
convert_erc20"receiver"{msg.Receiver}
convert_erc20"amount"{msg.Amount.String()}
convert_erc20"cosmos_coin"{denom}
convert_erc20"erc20_token"{msg.ContractAddress}

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Parameters​

The erc20 module contains the following parameters:
KeyTypeDefault Value
EnableErc20booltrue
EnableEVMHookbooltrue

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Enable ERC20​

The EnableErc20 parameter toggles all state transitions in the module. When the parameter is disabled, it will prevent all token pair registration and conversion functionality.

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Enable EVM Hook​

The EnableEVMHook parameter enables the EVM hook to convert an ERC20 token to a Cosmos Coin by transferring the Tokens through a MsgEthereumTx to the ModuleAddress Ethereum address.

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Clients​

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CLI​

Find below a list of appd commands added with the x/erc20 module. You can obtain the full list by using the appd -h command. A CLI command can look like this: 
appd query erc20 params

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Queries​

CommandSubcommandDescription
query erc20paramsGet erc20 params
query erc20token-pairGet registered token pair
query erc20token-pairsGet all registered token pairs

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Transactions​

CommandSubcommandDescription
tx erc20convert-coinConvert a Cosmos Coin to ERC20
tx erc20convert-erc20Convert a ERC20 to Cosmos Coin

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Proposals​

The tx gov submit-legacy-proposal commands allow users to query create a proposal using the governance module CLI: register-coin Allows users to submit a RegisterCoinProposal. Submit a proposal to register a Cosmos coin to the erc20 along with an initial deposit. Upon passing, the proposal details must be supplied via a JSON file. 
appd tx gov submit-legacy-proposal register-coin METADATA_FILE [flags]
Where METADATA_FILE contains (example): 
{  "metadata": [    {   "description": "The native staking and governance token of the Osmosis chain",   "denom_units": [    {      "denom": "ibc/<HASH>",      "exponent": 0,      "aliases": ["ibcuosmo"]    },    {      "denom": "OSMO",      "exponent": 6    }   ],   "base": "ibc/<HASH>",   "display": "OSMO",   "name": "Osmo",   "symbol": "OSMO"  } ]}
register-erc20 Allows users to submit a RegisterERC20Proposal. Submit a proposal to register ERC20 tokens along with an initial deposit. To register multiple tokens in one proposal pass them after each other e.g. register-erc20 <contract-address1> <contract-address2>. 
appd tx gov submit-legacy-proposal register-erc20 ERC20_ADDRESS... [flags]
toggle-token-conversion Allows users to submit a ToggleTokenConversionProposal. 
appd tx gov submit-legacy-proposal toggle-token-conversion TOKEN [flags]
Update Params Allows users to submit a MsgUpdateParams with the desired changes on the x/erc20 module parameters. To do this, you will have to provide a JSON file with the correspondiong message in the submit-proposal command. For more information on how to draft a proposal, refer to the Cosmos SDK governance documentation. 
appd tx gov submit-proposal proposal.json [flags]

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gRPC​

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Queries​

VerbMethodDescription
gRPCcosmos.evm.erc20.v1.Query/ParamsGet erc20 params
gRPCcosmos.evm.erc20.v1.Query/TokenPairGet registered token pair
gRPCcosmos.evm.erc20.v1.Query/TokenPairsGet all registered token pairs
GET/cosmos/evm/erc20/v1/paramsGet erc20 params
GET/cosmos/evm/erc20/v1/token_pairGet registered token pair
GET/cosmos/evm/erc20/v1/token_pairsGet all registered token pairs

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Transactions​

VerbMethodDescription
gRPCcosmos.evm.erc20.v1.Msg/ConvertCoinConvert a Cosmos Coin to ERC20
gRPCcosmos.evm.erc20.v1.Msg/ConvertERC20Convert a ERC20 to Cosmos Coin
GET/cosmos/evm/erc20/v1/tx/convert_coinConvert a Cosmos Coin to ERC20
GET/cosmos/evm/erc20/v1/tx/convert_erc20Convert a ERC20 to Cosmos Coin