IPC Addresses: Globally discoverable identifiers.

[adlrocha]

Background

In the MVP implementation of IPC we introduced the IPCAddress as a way to add subnet information to plain Filecoin address (see spec for an outdated description of this address). In the end, an IPCAddress is the combination of a SubnetID and a raw Filecoin address. IPCAddress is used to add context information of a subnet to an address when need to disambiguate, for instance, in the from and to fields of a cross-net message.

With FVM, a new type of address is introduced to the Filecoin network to support the creation of new user-defined actor addressing schemes. The f4 address has been mentioned in some discussions as a way to implement IPCAddress.

In our efforts to move IPC into production, and as we review the design we have for IPC, it may be worth re-considering the design of IPCAddress (and potential SubnetID) to make them more general and interoperable.

Requirements

At this point, an IPCAddress is serialized as any other Filecoin address (initially we even considered giving it the f04 address space before the FVM proposal came), however we may not need to constraint ourselves to represent an IPCAddress as a canonical fielcoin address, and we may want to make it an identifier to universally identify resources in any IPC subnet (or any blockchain?).

What IPC requires from an IPCAddress is a way to:

• Add subnet information to any address (externally owned or on-chain).
• A way to create an IPCAddress from a raw address and viceversa.
• Have a "human-readable" serialization so wallets and applications have an "amenable" way of handling these addresses.

RFP

The goal of the discussion is to collect proposals and ideas around the design of IPC addresses, and to agree on a design. A few of the questions that we should solve with the design:

• Do we want to follow Filecoin addresses encodings?
• Can we leverage f04 addresses/delegated addresses for the design of IPCAddress.
• Should IPCAddress support raw addresses that are not Filecoin addresses? If yes, how are we going to determine the type of raw address wrapped into the IPCAddress?
• Can we use IPCAddress to identify other resources that are not just addresses (like blocks, transactions, etc.)? Is there value in this?
• Are we happy with the current design of SubnetID? Does it cover all our needs?

[anorth]

I am excited by the potential to solve address ambiguity across all of web3, not just Filecoin. I would really like to see something universal (which implies not caring about Filecoin address encodings, except to embed them in something like a multiaddr).