Proposal: Cosmos transaction signing support

[tarcieri]

EDIT: this issue has been moved to iqlusioninc/tmkms#54

[tarcieri]

Regarding building Cosmos SDK-compatible transactions from Rust, it looks like the deep_space crate is capable of this, but is a bit rough around the edges.

[jleni]

About your open question wrt Ledger devices..
The cosmos app already does everything that is needed, however for security reasons, at the moment always requires manual confirmation.

Extending the rust driver to support both Tendermint and Cosmos apps, should be fairly easy.

The only change the app needs is to have a menu option so users can enable/disable "sign without confirmation". BUT, I am not sure Ledger will accept this feature unless it is released with a big warning.

I would prefer to limit by protocol which tx types can be signed without confirmation. That way the check can be done inside the secure element and not in the KMS software layer.

[tarcieri]

@jleni would it be possible to compose and upload some sort of ACL which can be displayed on the device, confirmed, and then stored to enable subsequent "sign without confirmation" usage?

[gaia]

(Maybe not the place for this suggestion, and definitely too early. LMK I will remove it)

Reading in #361 that proposal would give the ability to sign messages: please structure this so that (down the line) messages can be stored in IPFS (for larger files, such as PDFs) or similar file storage protocol. A digital notary is a real world business use case with large demand. The current landscape for PAdES-Long Term Validation PDF signature/certification is an oligopoly maintained by Adobe and a few trusted partners (AATL), with complex implementation, exorbitant costs, and outdated technology.

PS: I would be interested in using a PDF digital notary for my other (non blockchain related) company.

[tarcieri]

@gaia to the extent this can be used as a digital notary service, I think the main idea here would be notarizing things as Cosmos transactions, which are validated and stored by a Tendermint application which understands the Cosmos SDK transaction format.

Anything more general than that, beyond generalizing something which could be used to produce Cosmos SDK-compatible transactions, I'd suggest discussing on #361 instead.

[jleni]

@tarcieri yes, it should be possible. It should be quite simple due to hardware constraints.. but we could design some grammar + set of rules: and, not, field matches value, field greater than X, etc.