KMS Signing support for relayer txs

[ebuchman]

As discussed in this Stargate issue and elsewhere, IBC messages in Stargate cannot be signed yet by Ledgers.

We should add hardware support for IBC message signing through the TMKMS. @zmanian @tony-iqlusion are there issues for this?

[tony-iqlusion]

It should certainly be doable via a YubiHSM2.

How are you foreseeing an IBC relayer interacting with TMKMS? Would you like for TMKMS to expose a gRPC service?

[zmanian]

My mental model is similar to the oracle architecture maybe.

[ebuchman]

Yeh I think a gRPC makes sense, is that what the oracle uses ?

I guess there would also be the option for the rust relayer of running in process but that seems special case.

Any thoughts here @ancazamfir

[tony-iqlusion]

@ebuchman the current transaction signer uses a JSON/HTTP webhook (which makes outgoing requests).

At the time we implemented it we needed Amino support, so it was easier to get started with Amino JSON.

However, now we have tendermint-proto, cosmos-sdk-proto, and cosmos-tx, so we can start working on defining a gRPC service.

[nooomski]

Is this still relevant or can we close this? @ebuchman Not too familiar with IBC status on this. Thanks

[romac]

There's no support for TMKMS in Hermes at the moment, so we can maybe keep this issue open to discuss relayer integration with TMKMS?

[tony-iqlusion]

Would be good to discuss this after we have initial gRPC support

[ebuchman]

I think the original issue may still stand but it prob doesn't need to be in this repo. @charleenfei @jackzampolin do you know if relayer txs can be signed by hardware yet ? should we move this issue somewhere to track it? I believe all relayers are currently just using text file private keys and that might be fine for now but as relayer balances increase this may become higher priority - cc @adizere @greg-szabo

[mmulji-ic]

AFAIK This issue is no longer relevant, we'll close, please reopen if incorrect.