# State

### Signing Info (Liveness) <a href="#signing-info-liveness" id="signing-info-liveness"></a>

Every block includes a set of precommits by the validators for the previous block, known as the `LastCommitInfo` provided by Tendermint. A `LastCommitInfo` is valid so long as it contains precommits from +2/3 of total voting power.

Proposers are incentivized to include precommits from all validators in the Tendermint `LastCommitInfo` by receiving additional fees proportional to the difference between the voting power included in the `LastCommitInfo` and +2/3 (see fee distribution).

```go
type LastCommitInfo struct {
	Round int32
	Votes []VoteInfo
}
```

Validators are penalized for failing to be included in the `LastCommitInfo` for some number of blocks by being automatically jailed, potentially slashed, and unbonded.

Information about validator's liveness activity is tracked through `ValidatorSigningInfo`. It is indexed in the store as follows:

* ValidatorSigningInfo: `0x01 | ConsAddrLen (1 byte) | ConsAddress -> ProtocolBuffer(ValSigningInfo)`
* MissedBlocksBitArray: `0x02 | ConsAddrLen (1 byte) | ConsAddress | LittleEndianUint64(signArrayIndex) -> VarInt(didMiss)` (varint is a number encoding format)

The first mapping allows us to easily lookup the recent signing info for a validator based on the validator's consensus address.

The second mapping (`MissedBlocksBitArray`) acts as a bit-array of size `SignedBlocksWindow` that tells us if the validator missed the block for a given index in the bit-array. The index in the bit-array is given as little endian uint64.&#x20;

The result is a `varint` that takes on `0` or `1`, where `0` indicates the validator did not miss (did sign) the corresponding block, and `1` indicates they missed the block (did not sign).

Note that the `MissedBlocksBitArray` is not explicitly initialized up-front. Keys are added as we progress through the first `SignedBlocksWindow` blocks for a newly bonded validator. The `SignedBlocksWindow` parameter defines the size (number of blocks) of the sliding window used to track validator liveness.

The information stored for tracking validator liveness is as follows:

```protobuf
// ValidatorSigningInfo defines a validator's signing info for monitoring their
// liveness activity.
message ValidatorSigningInfo {
  option (gogoproto.equal)            = true;
  option (gogoproto.goproto_stringer) = false;

  string address = 1 [(cosmos_proto.scalar) = "cosmos.AddressString"];
  // Height at which validator was first a candidate OR was unjailed
  int64 start_height = 2;
  // Index which is incremented each time the validator was a bonded
  // in a block and may have signed a precommit or not. This in conjunction with the
  // `SignedBlocksWindow` param determines the index in the `MissedBlocksBitArray`.
  int64 index_offset = 3;
  // Timestamp until which the validator is jailed due to liveness downtime.
  google.protobuf.Timestamp jailed_until = 4 [(gogoproto.stdtime) = true, (gogoproto.nullable) = false];
  // Whether or not a validator has been tombstoned (killed out of validator set). It is set
  // once the validator commits an equivocation or for any other configured misbehiavor.
  bool tombstoned = 5;
  // A counter kept to avoid unnecessary array reads.
  // Note that `Sum(MissedBlocksBitArray)` always equals `MissedBlocksCounter`.
  int64 missed_blocks_counter = 6;
}
```

### Params <a href="#params" id="params"></a>

The slashing module stores it's params in state with the prefix of `0x00`, it can be updated with governance or the address with authority.

* Params: `0x00 | ProtocolBuffer(Params)`

```protobuf
// Params represents the parameters used for by the slashing module.
message Params {
  int64 signed_blocks_window  = 1;
  bytes min_signed_per_window = 2
      [(gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Dec", (gogoproto.nullable) = false];
  google.protobuf.Duration downtime_jail_duration = 3 [(gogoproto.nullable) = false, (gogoproto.stdduration) = true];
  bytes                    slash_fraction_double_sign = 4
      [(gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Dec", (gogoproto.nullable) = false];
  bytes slash_fraction_downtime = 5
      [(gogoproto.customtype) = "github.com/cosmos/cosmos-sdk/types.Dec", (gogoproto.nullable) = false];
}
```