prysm-pulse/beacon-chain/core/attestations/attestation.go
Nishant Das 929bc04211
Implement IsSurroundVote, IsDoubleVote, GetForkVersion,GetDomain helpers (#1180)
* Adding vote helpers

* Adding fork/domain helpers

* Adding comments

* visibility

* removing misc package
2018-12-28 15:29:02 +08:00

108 lines
3.9 KiB
Go

package attestations
import (
"encoding/binary"
pb "github.com/prysmaticlabs/prysm/proto/beacon/p2p/v1"
"github.com/prysmaticlabs/prysm/shared/hashutil"
"github.com/prysmaticlabs/prysm/shared/params"
)
// CreateAttestationMsg hashes parentHashes + shardID + slotNumber +
// shardBlockHash + justifiedSlot into a message to use for verifying
// with aggregated public key and signature.
func CreateAttestationMsg(
blockHash []byte,
slot uint64,
shardID uint64,
justifiedSlot uint64,
forkVersion uint64,
) [32]byte {
msg := make([]byte, binary.MaxVarintLen64)
binary.BigEndian.PutUint64(msg, forkVersion)
binary.PutUvarint(msg, slot%params.BeaconConfig().CycleLength)
binary.PutUvarint(msg, shardID)
msg = append(msg, blockHash...)
binary.PutUvarint(msg, justifiedSlot)
return hashutil.Hash(msg)
}
// Key generates the blake2b hash of the following attestation fields:
// slotNumber + shardID + blockHash + obliqueParentHash
// This is used for attestation table look up in localDB.
func Key(att *pb.AttestationData) [32]byte {
key := make([]byte, binary.MaxVarintLen64)
binary.PutUvarint(key, att.GetSlot())
binary.PutUvarint(key, att.GetShard())
key = append(key, att.GetShardBlockRootHash32()...)
return hashutil.Hash(key)
}
// VerifyProposerAttestation verifies the proposer's attestation of the block.
// Proposers broadcast the attestation along with the block to its peers.
func VerifyProposerAttestation(att *pb.AttestationData, pubKey [32]byte, proposerShardID uint64) error {
// Verify the attestation attached with block response.
// Get proposer index and shardID.
attestationMsg := CreateAttestationMsg(
att.GetShardBlockRootHash32(),
att.GetSlot(),
proposerShardID,
att.GetJustifiedSlot(),
params.BeaconConfig().InitialForkVersion,
)
_ = attestationMsg
_ = pubKey
// TODO(#258): use attestationMsg to verify against signature
// and public key. Return error if incorrect.
return nil
}
// ContainsValidator checks if the validator is included in the attestation.
// TODO(#569): Modify method to accept a single index rather than a bitfield.
func ContainsValidator(attesterBitfield []byte, bitfield []byte) bool {
for i := 0; i < len(bitfield); i++ {
if bitfield[i]&attesterBitfield[i] != 0 {
return true
}
}
return false
}
// IsDoubleVote checks if both of the attestations have been used to vote for the same slot.
// Spec:
// def is_double_vote(attestation_data_1: AttestationData,
// attestation_data_2: AttestationData) -> bool
// """
// Assumes ``attestation_data_1`` is distinct from ``attestation_data_2``.
// Returns True if the provided ``AttestationData`` are slashable
// due to a 'double vote'.
// """
// return attestation_data_1.slot == attestation_data_2.slot
func IsDoubleVote(attestation1 *pb.AttestationData, attestation2 *pb.AttestationData) bool {
return attestation1.Slot == attestation2.Slot
}
// IsSurroundVote checks if the data provided by the attestations fulfill the conditions for
// a surround vote.
// Spec:
// def is_surround_vote(attestation_data_1: AttestationData,
// attestation_data_2: AttestationData) -> bool:
// """
// Assumes ``attestation_data_1`` is distinct from ``attestation_data_2``.
// Returns True if the provided ``AttestationData`` are slashable
// due to a 'surround vote'.
// Note: parameter order matters as this function only checks
// that ``attestation_data_1`` surrounds ``attestation_data_2``.
// """
// return (
// (attestation_data_1.justified_slot < attestation_data_2.justified_slot) and
// (attestation_data_2.justified_slot + 1 == attestation_data_2.slot) and
// (attestation_data_2.slot < attestation_data_1.slot)
// )
func IsSurroundVote(attestation1 *pb.AttestationData, attestation2 *pb.AttestationData) bool {
return attestation1.JustifiedSlot < attestation2.JustifiedSlot &&
attestation2.JustifiedSlot+1 == attestation2.Slot &&
attestation2.Slot < attestation1.Slot
}