tokenfactory

Token Factory

The tokenfactory module allows any account to create a new token with the name factory/{creator address}/{subdenom}. Because tokens are namespaced by creator address, this allows token minting to be permissionless, due to not needing to resolve name collisions. A single account can create multiple denoms, by providing a unique subdenom for each created denom. Once a denom is created, the original creator is given "admin" privileges over the asset. This allows them to:

• Mint their denom to any account
• Burn their denom from any account
• Create a transfer of their denom between any two accounts
• Change the admin. In the future, more admin capabilities may be added. Admins can choose to share admin privileges with other accounts using the authz module. The ChangeAdmin functionality, allows changing the master admin account, or even setting it to "", meaning no account has admin privileges of the asset.

Messages

CreateDenom

Creates a denom of factory/{creator address}/{subdenom} given the denom creator address and the subdenom. Subdenoms can contain [a-zA-Z0-9./].

message MsgCreateDenom {
  string sender = 1 [ (gogoproto.moretags) = "yaml:\"sender\"" ];
  string subdenom = 2 [ (gogoproto.moretags) = "yaml:\"subdenom\"" ];
}

State Modifications:

• Fund community pool with the denom creation fee from the creator address, set in Params.
• Set DenomMetaData via bank keeper.
• Set AuthorityMetadata for the given denom to store the admin for the created denom factory/{creator address}/{subdenom}. Admin is automatically set as the Msg sender.
• Add denom to the CreatorPrefixStore, where a state of denoms created per creator is kept.

Mint

Minting of a specific denom is only allowed for the current admin. Note, the current admin is defaulted to the creator of the denom.

message MsgMint {
  string sender = 1 [ (gogoproto.moretags) = "yaml:\"sender\"" ];
  cosmos.base.v1beta1.Coin amount = 2 [
    (gogoproto.moretags) = "yaml:\"amount\"",
    (gogoproto.nullable) = false
  ];
}

State Modifications:

• Safety check the following
  • Check that the denom minting is created via tokenfactory module
  • Check that the sender of the message is the admin of the denom
• Mint designated amount of tokens for the denom via bank module

Burn

Burning of a specific denom is only allowed for the current admin. Note, the current admin is defaulted to the creator of the denom.

message MsgBurn {
  string sender = 1 [ (gogoproto.moretags) = "yaml:\"sender\"" ];
  cosmos.base.v1beta1.Coin amount = 2 [
    (gogoproto.moretags) = "yaml:\"amount\"",
    (gogoproto.nullable) = false
  ];
}

State Modifications:

• Saftey check the following
  • Check that the denom minting is created via tokenfactory module
  • Check that the sender of the message is the admin of the denom
• Burn designated amount of tokens for the denom via bank module

ChangeAdmin

Change the admin of a denom. Note, this is only allowed to be called by the current admin of the denom.

message MsgChangeAdmin {
  string sender = 1 [ (gogoproto.moretags) = "yaml:\"sender\"" ];
  string denom = 2 [ (gogoproto.moretags) = "yaml:\"denom\"" ];
  string newAdmin = 3 [ (gogoproto.moretags) = "yaml:\"new_admin\"" ];
}

SetDenomMetadata

Setting of metadata for a specific denom is only allowed for the admin of the denom. It allows the overwriting of the denom metadata in the bank module.

message MsgChangeAdmin {
  string sender = 1 [ (gogoproto.moretags) = "yaml:\"sender\"" ];
  cosmos.bank.v1beta1.Metadata metadata = 2 [ (gogoproto.moretags) = "yaml:\"metadata\"", (gogoproto.nullable)   = false ];
}

State Modifications:

• Check that sender of the message is the admin of denom
• Modify AuthorityMetadata state entry to change the admin of the denom

Expectations from the chain

The chain's bech32 prefix for addresses can be at most 16 characters long.

This comes from denoms having a 128 byte maximum length, enforced from the SDK, and us setting longest_subdenom to be 44 bytes.

A token factory token's denom is: factory/{creator address}/{subdenom}

Splitting up into sub-components, this has:

• len(factory) = 7
• 2 * len("/") = 2
• len(longest_subdenom)
• len(creator_address) = len(bech32(longest_addr_length, chain_addr_prefix)).

Longest addr length at the moment is 32 bytes. Due to SDK error correction settings, this means len(bech32(32, chain_addr_prefix)) = len(chain_addr_prefix) + 1 + 58. Adding this all, we have a total length constraint of 128 = 7 + 2 + len(longest_subdenom) + len(longest_chain_addr_prefix) + 1 + 58. Therefore len(longest_subdenom) + len(longest_chain_addr_prefix) = 128 - (7 + 2 + 1 + 58) = 60.

The choice between how we standardized the split these 60 bytes between maxes from longest_subdenom and longest_chain_addr_prefix is somewhat arbitrary. Considerations going into this:

• Per BIP-0173 the technically longest HRP for a 32 byte address ('data field') is 31 bytes. (Comes from encode(data) = 59 bytes, and max length = 90 bytes)
• subdenom should be at least 32 bytes so hashes can go into it
• longer subdenoms are very helpful for creating human readable denoms
• chain addresses should prefer being smaller. The longest HRP in cosmos to date is 11 bytes. (persistence)

For explicitness, its currently set to len(longest_subdenom) = 44 and len(longest_chain_addr_prefix) = 16.

Please note, if the SDK increases the maximum length of a denom from 128 bytes, these caps should increase.

So please don't make code rely on these max lengths for parsing.