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randao.go
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randao.go
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package blocks
import (
"context"
"github.com/pkg/errors"
ethpb "github.com/prysmaticlabs/ethereumapis/eth/v1alpha1"
"github.com/prysmaticlabs/prysm/beacon-chain/core/helpers"
iface "github.com/prysmaticlabs/prysm/beacon-chain/state/interface"
"github.com/prysmaticlabs/prysm/shared/hashutil"
"github.com/prysmaticlabs/prysm/shared/params"
)
// ProcessRandao checks the block proposer's
// randao commitment and generates a new randao mix to update
// in the beacon state's latest randao mixes slice.
//
// Spec pseudocode definition:
// def process_randao(state: BeaconState, body: BeaconBlockBody) -> None:
// epoch = get_current_epoch(state)
// # Verify RANDAO reveal
// proposer = state.validators[get_beacon_proposer_index(state)]
// signing_root = compute_signing_root(epoch, get_domain(state, DOMAIN_RANDAO))
// assert bls.Verify(proposer.pubkey, signing_root, body.randao_reveal)
// # Mix in RANDAO reveal
// mix = xor(get_randao_mix(state, epoch), hash(body.randao_reveal))
// state.randao_mixes[epoch % EPOCHS_PER_HISTORICAL_VECTOR] = mix
func ProcessRandao(
_ context.Context,
beaconState iface.BeaconState,
b *ethpb.SignedBeaconBlock,
) (iface.BeaconState, error) {
if err := helpers.VerifyNilBeaconBlock(b); err != nil {
return nil, err
}
body := b.Block.Body
buf, proposerPub, domain, err := randaoSigningData(beaconState)
if err != nil {
return nil, err
}
if err := verifySignature(buf, proposerPub, body.RandaoReveal, domain); err != nil {
return nil, errors.Wrap(err, "could not verify block randao")
}
beaconState, err = ProcessRandaoNoVerify(beaconState, body.RandaoReveal)
if err != nil {
return nil, errors.Wrap(err, "could not process randao")
}
return beaconState, nil
}
// ProcessRandaoNoVerify generates a new randao mix to update
// in the beacon state's latest randao mixes slice.
//
// Spec pseudocode definition:
// # Mix it in
// state.latest_randao_mixes[get_current_epoch(state) % LATEST_RANDAO_MIXES_LENGTH] = (
// xor(get_randao_mix(state, get_current_epoch(state)),
// hash(body.randao_reveal))
// )
func ProcessRandaoNoVerify(
beaconState iface.BeaconState,
randaoReveal []byte,
) (iface.BeaconState, error) {
currentEpoch := helpers.SlotToEpoch(beaconState.Slot())
// If block randao passed verification, we XOR the state's latest randao mix with the block's
// randao and update the state's corresponding latest randao mix value.
latestMixesLength := params.BeaconConfig().EpochsPerHistoricalVector
latestMixSlice, err := beaconState.RandaoMixAtIndex(uint64(currentEpoch % latestMixesLength))
if err != nil {
return nil, err
}
blockRandaoReveal := hashutil.Hash(randaoReveal)
if len(blockRandaoReveal) != len(latestMixSlice) {
return nil, errors.New("blockRandaoReveal length doesnt match latestMixSlice length")
}
for i, x := range blockRandaoReveal {
latestMixSlice[i] ^= x
}
if err := beaconState.UpdateRandaoMixesAtIndex(uint64(currentEpoch%latestMixesLength), latestMixSlice); err != nil {
return nil, err
}
return beaconState, nil
}