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Interchain Security Parameters

The parameters necessary for Interchain Security (ICS) are defined in

  • the Params structure in proto/interchain_security/ccv/provider/v1/provider.proto for the provider;
  • the Params structure in proto/interchain_security/ccv/consumer/v1/consumer.proto for the consumer.

Time-based parameters

ICS relies on the following time-based parameters.

  • UnbondingTime is defined in the x/staking module of the cosmos-sdk, i.e., see protobuf. This is the unbonding period on the provider chain. For clarity, we denote the unbonding periods on the provider by ProviderUnbondingPeriod
  • UnbondingPeriod is defined in consumer.proto and it is the unbonding period on the consumer chain. For clarity, we denote the unbonding periods on the consumer by ConsumerUnbondingPeriod. The ConsumerUnbondingPeriod is set via the ConsumerAdditionProposal gov proposal to add a new consumer chain. Unbonding operations (such as undelegations) MUST wait for the unbonding period on every consumer to elapse. Therefore, for an improved user experience, the ConsumerAdditionProposal on every consumer chain SHOULD be smaller than ProviderUnbondingPeriod, i.e., 
    ConsumerUnbondingPeriod = ProviderUnbondingPeriod - one day
  • TrustingPeriodFraction is used to calculate the TrustingPeriod of created IBC clients on both provider and consumer chains.
    For example, a TrustingPeriodFraction of 0.5 would entail that the TrustingPeriod of clients to the provider will be ProviderUnbondingPeriod / 2, while the TrustingPeriod of clients to every consumer will be ConsumerUnbondingPeriod / 2. Note that a client MUST be update within the TrustingPeriod in order to remain active. For more details, see the IBC specification of Tendermint clients.
  • CCVTimeoutPeriod is the period used to compute the timeout timestamp when sending IBC packets. For more details, see the IBC specification of Channel & Packet Semantics. CCVTimeoutPeriod may have different values on the provider and consumer chains. If a sent packet is not relayed within this period, then the packet times out, the CCV channel is closed, and the corresponding consumer removed. The CCVTimeoutPeriod on the provider MUST be larger than ConsumerUnbondingPeriod. The CCVTimeoutPeriod on the consumer is initial set via the ConsumerAdditionProposal gov proposal to add the consumer.
  • InitTimeoutPeriod is the maximum time duration the Channel Initialization subprotocol may execute, i.e., for any consumer chain, if the CCV channel is not established within InitTimeoutPeriod since the ConsumerAdditionProposal was handled (the client to the consumer was created), then the consumer chain is removed.
  • VscTimeoutPeriod is the maximum time duration between sending any VSCPacket to any consumer chain and receiving the corresponding VSCMaturedPacket, without timing out the consumer chain and consequently removing it. VscTimeoutPeriod MUST be larger than the ConsumerUnbondingPeriod.
  • BlocksPerDistributionTransmission is the number of blocks between rewards transfers from the consumer to the provider.
  • TransferPeriodTimeout is the period used to compute the timeout timestamp when sending IBC transfer packets from a consumer to the provider. If this timeout expires, then the transfer is attempted again after BlocksPerDistributionTransmission blocks. The TransferPeriodTimeout on the consumer is initial set via the ConsumerAdditionProposal gov proposal to add the consumer. The TransferPeriodTimeout SHOULD be smaller than BlocksPerDistributionTransmission x avg_block_time, to make it easier to reason about the distribution subprotocol.
  • SlashMeterReplenishPeriod exists on the provider such that once the slash meter becomes not-full, the slash meter is replenished after this period has elapsed. The meter is replenished to an amount equal to the slash meter allowance for that block, or SlashMeterReplenishFraction * CurrentTotalVotingPower.

Non-time-based parameters

ICS relies on the following non-time-based parameters.

  • SlashMeterReplenishFraction exists on the provider as the portion (in range [0, 1]) of total voting power that is replenished to the slash meter when a replenishment occurs. This param also serves as a maximum fraction of total voting power that the slash meter can hold. The param is set/persisted as a string, and converted to a sdk.Dec when used.
  • MaxThrottledPackets exists on the provider as the maximum amount of throttled slash or vsc matured packets that can be queued from a single consumer before the provider chain halts, it should be set to a large value. This param would allow provider binaries to panic deterministically in the event that packet throttling results in a large amount of state-bloat. In such a scenario, packet throttling could prevent a violation of safety caused by a malicious consumer, at the cost of provider liveness.