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types: remove VerifyFutureCommit (#4961)

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It was previously used by the now removed `lite` package.
This commit is contained in:
Anton Kaliaev
2020-06-05 16:31:30 +04:00
committed by GitHub
parent b4aca980e9
commit 245794a3fd
1 changed files with 0 additions and 76 deletions
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76
types/validator_set.go
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@@ -714,82 +714,6 @@ func (vals *ValidatorSet) VerifyCommit(chainID string, blockID BlockID,
return ErrNotEnoughVotingPowerSigned{Got: talliedVotingPower, Needed: votingPowerNeeded}
}
// VerifyFutureCommit will check to see if the set would be valid with a different
// validator set.
//
// vals is the old validator set that we know. Over 2/3 of the power in old
// signed this block.
//
// In Tendermint, 1/3 of the voting power can halt or fork the chain, but 1/3
// can't make arbitrary state transitions. You still need > 2/3 Byzantine to
// make arbitrary state transitions.
//
// To preserve this property in the light client, we also require > 2/3 of the
// old vals to sign the future commit at H, that way we preserve the property
// that if they weren't being truthful about the validator set at H (block hash
// -> vals hash) or about the app state (block hash -> app hash) we can slash
// > 2/3. Otherwise, the light client isn't providing the same security
// guarantees.
//
// Even if we added a slashing condition that if you sign a block header with
// the wrong validator set, then we would only need > 1/3 of signatures from
// the old vals on the new commit, it wouldn't be sufficient because the new
// vals can be arbitrary and commit some arbitrary app hash.
//
// newSet is the validator set that signed this block. Only votes from new are
// sufficient for 2/3 majority in the new set as well, for it to be a valid
// commit.
//
// NOTE: This doesn't check whether the commit is a future commit, because the
// current height isn't part of the ValidatorSet. Caller must check that the
// commit height is greater than the height for this validator set.
func (vals *ValidatorSet) VerifyFutureCommit(newSet *ValidatorSet, chainID string,
blockID BlockID, height int64, commit *Commit) error {
oldVals := vals
// Commit must be a valid commit for newSet.
err := newSet.VerifyCommit(chainID, blockID, height, commit)
if err != nil {
return err
}
// Check old voting power.
oldVotingPower := int64(0)
seen := map[int32]bool{}
for idx, commitSig := range commit.Signatures {
if commitSig.Absent() {
continue // OK, some signatures can be absent.
}
// See if this validator is in oldVals.
oldIdx, val := oldVals.GetByAddress(commitSig.ValidatorAddress)
if val == nil || seen[oldIdx] {
continue // missing or double vote...
}
seen[oldIdx] = true
// Validate signature.
voteSignBytes := commit.VoteSignBytes(chainID, int32(idx))
if !val.PubKey.VerifyBytes(voteSignBytes, commitSig.Signature) {
return fmt.Errorf("wrong signature (#%d): %X", idx, commitSig.Signature)
}
// Good!
if blockID.Equals(commitSig.BlockID(commit.BlockID)) {
oldVotingPower += val.VotingPower
}
// else {
// It's OK that the BlockID doesn't match. We include stray
// signatures (~votes for nil) to measure validator availability.
// }
}
if got, needed := oldVotingPower, oldVals.TotalVotingPower()*2/3; got <= needed {
return ErrNotEnoughVotingPowerSigned{Got: got, Needed: needed}
}
return nil
}
// VerifyCommitTrusting verifies that trustLevel of the validator set signed
// this commit.
//