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remove unneccessary checks
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@seunlanlege
seunlanlege committed Apr 1, 2022
1 parent 2a72aa0 commit 6d62eda
Showing 1 changed file with 104 additions and 107 deletions.
211 changes: 104 additions & 107 deletions modules/light-clients/11-beefy/types/update.go
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Original file line number Diff line number Diff line change
Expand Up @@ -68,126 +68,123 @@ func (cs *ClientState) CheckHeaderAndUpdateState(
)
}

// a new mmr update has arrived
if beefyHeader.MmrUpdateProof != nil {
var (
mmrUpdateProof = beefyHeader.MmrUpdateProof
authoritiesProof = beefyHeader.MmrUpdateProof.AuthoritiesProof
signedCommitment = beefyHeader.MmrUpdateProof.SignedCommitment
)

// checking signatures is expensive (667 authorities for kusama),
// we want to know if these sigs meet the minimum threshold before proceeding
// and are by a known authority set (the current one, or the next one)
if authoritiesThreshold(*cs.Authority) > uint32(len(signedCommitment.Signatures)) ||
authoritiesThreshold(*cs.NextAuthoritySet) > uint32(len(signedCommitment.Signatures)) {
// todo: error commitment isn't final
return nil, nil, nil
}
var (
mmrUpdateProof = beefyHeader.MmrUpdateProof
authoritiesProof = beefyHeader.MmrUpdateProof.AuthoritiesProof
signedCommitment = beefyHeader.MmrUpdateProof.SignedCommitment
)

// checking signatures is expensive (667 authorities for kusama),
// we want to know if these sigs meet the minimum threshold before proceeding
// and are by a known authority set (the current one, or the next one)
if authoritiesThreshold(*cs.Authority) > uint32(len(signedCommitment.Signatures)) ||
authoritiesThreshold(*cs.NextAuthoritySet) > uint32(len(signedCommitment.Signatures)) {
// todo: error commitment isn't final
return nil, nil, nil
}

if signedCommitment.Commitment.ValidatorSetId != cs.Authority.Id &&
signedCommitment.Commitment.ValidatorSetId != cs.NextAuthoritySet.Id {
// todo: authority set is unknown
return nil, nil, nil
}
if signedCommitment.Commitment.ValidatorSetId != cs.Authority.Id &&
signedCommitment.Commitment.ValidatorSetId != cs.NextAuthoritySet.Id {
// todo: authority set is unknown
return nil, nil, nil
}

// beefy authorities are signing the hash of the scale-encoded Commitment
commitmentBytes, err := Encode(&signedCommitment.Commitment)
if err != nil {
// todo: proper errors
return nil, nil, err
}
// beefy authorities are signing the hash of the scale-encoded Commitment
commitmentBytes, err := Encode(&signedCommitment.Commitment)
if err != nil {
// todo: proper errors
return nil, nil, err
}

// take keccak hash of the commitment scale-encoded
commitmentHash := crypto.Keccak256(commitmentBytes)
// take keccak hash of the commitment scale-encoded
commitmentHash := crypto.Keccak256(commitmentBytes)

// array of leaves in the authority merkle root.
var authorityLeaves []merkle.Leaf
// array of leaves in the authority merkle root.
var authorityLeaves []merkle.Leaf

for i := 0; i < len(signedCommitment.Signatures); i++ {
signature := signedCommitment.Signatures[i]
// recover uncompressed public key from signature
pubkey, err := crypto.SigToPub(commitmentHash, signature.Signature)
for i := 0; i < len(signedCommitment.Signatures); i++ {
signature := signedCommitment.Signatures[i]
// recover uncompressed public key from signature
pubkey, err := crypto.SigToPub(commitmentHash, signature.Signature)

if err != nil {
// todo: error failed to recover signature!
return nil, nil, err
}
if err != nil {
// todo: error failed to recover signature!
return nil, nil, err
}

// convert public key to ethereum address.
address := crypto.PubkeyToAddress(*pubkey)
authorityLeaf := merkle.Leaf{
Hash: crypto.Keccak256(address[:]),
Index: signature.AuthorityIndex,
}
authorityLeaves = append(authorityLeaves, authorityLeaf)
// convert public key to ethereum address.
address := crypto.PubkeyToAddress(*pubkey)
authorityLeaf := merkle.Leaf{
Hash: crypto.Keccak256(address[:]),
Index: signature.AuthorityIndex,
}
authorityLeaves = append(authorityLeaves, authorityLeaf)
}

// flag for if the authority set has been updated
updatedAuthority := false

// assert that known authorities signed this commitment, only 2 cases because we already
// made a prior check to assert that authorities are known
switch signedCommitment.Commitment.ValidatorSetId {
case cs.Authority.Id:
// here we construct a merkle proof, and verify that the public keys which produced this signature
// are part of the current round.
authoritiesProof := merkle.NewProof(authorityLeaves, authoritiesProof, cs.Authority.Len, Keccak256{})
valid, err := authoritiesProof.Verify(cs.Authority.AuthorityRoot[:])
if err != nil || !valid {
// todo: error unknown authority set!
return nil, nil, nil
}
// flag for if the authority set has been updated
updatedAuthority := false

// assert that known authorities signed this commitment, only 2 cases because we already
// made a prior check to assert that authorities are known
switch signedCommitment.Commitment.ValidatorSetId {
case cs.Authority.Id:
// here we construct a merkle proof, and verify that the public keys which produced this signature
// are part of the current round.
authoritiesProof := merkle.NewProof(authorityLeaves, authoritiesProof, cs.Authority.Len, Keccak256{})
valid, err := authoritiesProof.Verify(cs.Authority.AuthorityRoot[:])
if err != nil || !valid {
// todo: error unknown authority set!
return nil, nil, nil
}

// new authority set has kicked in
case cs.NextAuthoritySet.Id:
authoritiesProof := merkle.NewProof(authorityLeaves, authoritiesProof, cs.NextAuthoritySet.Len, Keccak256{})
valid, err := authoritiesProof.Verify(cs.NextAuthoritySet.AuthorityRoot[:])
if err != nil || !valid {
// todo: error unknown authority set!
return nil, nil, nil
}
updatedAuthority = true
// new authority set has kicked in
case cs.NextAuthoritySet.Id:
authoritiesProof := merkle.NewProof(authorityLeaves, authoritiesProof, cs.NextAuthoritySet.Len, Keccak256{})
valid, err := authoritiesProof.Verify(cs.NextAuthoritySet.AuthorityRoot[:])
if err != nil || !valid {
// todo: error unknown authority set!
return nil, nil, nil
}
updatedAuthority = true
}

// only update if we have a higher block number.
if signedCommitment.Commitment.BlockNumer > cs.LatestBeefyHeight {
for _, payload := range signedCommitment.Commitment.Payload {
mmrRootId := []byte("mh")
// checks for the right payloadId
if bytes.Equal(payload.PayloadId[:], mmrRootId) {
// the next authorities are in the latest BeefyMmrLeaf

// scale encode the mmr leaf
mmrLeafBytes, err := Encode(mmrUpdateProof.MmrLeaf)
if err != nil {
return nil, nil, err
}
// we treat this leaf as the latest leaf in the mmr
mmrSize := mmr.LeafIndexToMMRSize(mmrUpdateProof.MmrLeafIndex)
mmrLeaves := []mmr.Leaf{
{
Hash: crypto.Keccak256(mmrLeafBytes),
Index: mmrUpdateProof.MmrLeafIndex,
},
}
mmrProof := mmr.NewProof(mmrSize, mmrUpdateProof.MmrProof, mmrLeaves, Keccak256{})
// verify that the leaf is valid, for the signed mmr-root-hash
if !mmrProof.Verify(payload.PayloadData[:]) {
return nil, nil, err // error!, mmr proof is invalid
}
// update the block_number
cs.LatestBeefyHeight = signedCommitment.Commitment.BlockNumer
// updates the mmr_root_hash
cs.MmrRootHash = payload.PayloadData[:]
// authority set has changed, rotate our view of the authorities
if updatedAuthority {
cs.Authority = cs.NextAuthoritySet
// mmr leaf has been verified, use it to update our view of the next authority set
cs.NextAuthoritySet = &mmrUpdateProof.MmrLeaf.BeefyNextAuthoritySet
}
break
// only update if we have a higher block number.
if signedCommitment.Commitment.BlockNumer > cs.LatestBeefyHeight {
for _, payload := range signedCommitment.Commitment.Payload {
mmrRootId := []byte("mh")
// checks for the right payloadId
if bytes.Equal(payload.PayloadId[:], mmrRootId) {
// the next authorities are in the latest BeefyMmrLeaf

// scale encode the mmr leaf
mmrLeafBytes, err := Encode(mmrUpdateProof.MmrLeaf)
if err != nil {
return nil, nil, err
}
// we treat this leaf as the latest leaf in the mmr
mmrSize := mmr.LeafIndexToMMRSize(mmrUpdateProof.MmrLeafIndex)
mmrLeaves := []mmr.Leaf{
{
Hash: crypto.Keccak256(mmrLeafBytes),
Index: mmrUpdateProof.MmrLeafIndex,
},
}
mmrProof := mmr.NewProof(mmrSize, mmrUpdateProof.MmrProof, mmrLeaves, Keccak256{})
// verify that the leaf is valid, for the signed mmr-root-hash
if !mmrProof.Verify(payload.PayloadData[:]) {
return nil, nil, err // error!, mmr proof is invalid
}
// update the block_number
cs.LatestBeefyHeight = signedCommitment.Commitment.BlockNumer
// updates the mmr_root_hash
cs.MmrRootHash = payload.PayloadData[:]
// authority set has changed, rotate our view of the authorities
if updatedAuthority {
cs.Authority = cs.NextAuthoritySet
// mmr leaf has been verified, use it to update our view of the next authority set
cs.NextAuthoritySet = &mmrUpdateProof.MmrLeaf.BeefyNextAuthoritySet
}
break
}
}
}
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