Overview
Learn about what the Interchain Accounts module is
What is the Interchain Accounts module?
Interchain Accounts is the Cosmos SDK implementation of the ICS-27 protocol, which enables cross-chain account management built upon IBC.
- How does an interchain account differ from a regular account?
Regular accounts use a private key to sign transactions. Interchain Accounts are instead controlled programmatically by counterparty chains via IBC packets.
Concepts
Host Chain: The chain where the interchain account is registered. The host chain listens for IBC packets from a controller chain which should contain instructions (e.g. Cosmos SDK messages) for which the interchain account will execute.
Controller Chain: The chain registering and controlling an account on a host chain. The controller chain sends IBC packets to the host chain to control the account.
Interchain Account: An account on a host chain created using the ICS-27 protocol. An interchain account has all the capabilities of a normal account. However, rather than signing transactions with a private key, a controller chain will send IBC packets to the host chain which signals what transactions the interchain account should execute.
Authentication Module: A custom application module on the controller chain that uses the Interchain Accounts module to build custom logic for the creation & management of interchain accounts. It can be either an IBC application module using the legacy API, or a regular Cosmos SDK application module sending messages to the controller submodule's MsgServer (this is the recommended approach from ibc-go v6 if access to packet callbacks is not needed). Please note that the legacy API will eventually be removed and IBC applications will not be able to use them in later releases.
SDK security model
SDK modules on a chain are assumed to be trustworthy. For example, there are no checks to prevent an untrustworthy module from accessing the bank keeper.
The implementation of ICS-27 in ibc-go uses this assumption in its security considerations.
The implementation assumes other IBC application modules will not bind to ports within the ICS-27 namespace.
Channel Closure
The provided interchain account host and controller implementations do not support ChanCloseInit. However, they do support ChanCloseConfirm.
This means that the host and controller modules cannot close channels, but they will confirm channel closures initiated by other implementations of ICS-27.
In the event of a channel closing (due to a packet timeout in an ordered channel, for example), the interchain account associated with that channel can become accessible again if a new channel is created with a (JSON-formatted) version string that encodes the exact same Metadata information of the previous channel. The channel can be reopened using either MsgRegisterInterchainAccount or MsgChannelOpenInit. If MsgRegisterInterchainAccount is used, then it is possible to leave the version field of the message empty, since it will be filled in by the controller submodule. If MsgChannelOpenInit is used, then the version field must be provided with the correct JSON-encoded Metadata string. See section Understanding Active Channels for more information.
When reopening a channel with the default controller submodule, the ordering of the channel cannot be changed. In order to change the ordering of the channel, the channel has to go through a channel upgrade handshake or reopen the channel with a custom controller implementation.