# Signing Info (Liveness)
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
by receiving additional fees proportional to the difference between the voting
power included in the
LastCommitInfo and +2/3 (see fee distribution).
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
It is indexed in the store as follows:
0x01 | ConsAddrLen (1 byte) | ConsAddress -> ProtocolBuffer(ValSigningInfo)
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 (
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.
The result is a
varint that takes on
0 indicates the
validator did not miss (did sign) the corresponding block, and
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: