[Feature]: Require one active validator to opt-in for a consumer chain to launch

[mpoke]

Summary

Currently, the requirement for a consumer chain to launch is to have at least one eligible validator opted in. This includes inactive validators. Given the relative low cost of creating an inactive validator (see https://www.mintscan.io/cosmos/validators), an attacker could launch a large number of consumer chains. Currently, ICS is a "push" protocol, i.e., the provider sends validator updates to all the launched consumer chains. Since this happens in the EndBlock of the provider module, there is a risk of DOS attacks.

Problem Definition

No response

Proposed Feature

A long-term solution is to make ICS a "pull" protocol. Basically, consumer chains will need to query the provider validator updates using interchain queries. This will take time to implement.

In the meantime, a short-term solution is to require at least one active validator to opt-in on a consumer chain for that chain to launch.

Work Breakdown

Must have

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1. add extra condition to the consumer launch logic in provider module

[mpoke]

@insumity could you please also limit the number of consumer chains a validator could opt in? It should be a provider param and the default to something like 1000.