complete switching to v0.2.0 RANDAO scheme, with verification enabled

beacon_chain/beacon_node.nim

@@ -131,7 +131,6 @@ proc addLocalValidators*(node: BeaconNode) =
     let
       privKey = validator.privKey
       pubKey = privKey.pubKey()
-      randao = validator.randao
 
     let idx = node.beaconState.validator_registry.findIt(it.pubKey == pubKey)
     if idx == -1:
@@ -139,7 +138,7 @@ proc addLocalValidators*(node: BeaconNode) =
     else:
       debug "Attaching validator", validator = shortValidatorKey(node, idx),
                                    idx, pubKey
-      node.attachedValidators.addLocalValidator(idx, pubKey, privKey, randao)
+      node.attachedValidators.addLocalValidator(idx, pubKey, privKey)
 
   info "Local validators attached ", count = node.attachedValidators.count
 
@@ -216,7 +215,7 @@ proc proposeBlock(node: BeaconNode,
   var newBlock = BeaconBlock(
     slot: slot,
     parent_root: node.headBlockRoot,
-    randao_reveal: validator.genRandaoReveal(state),
+    randao_reveal: validator.genRandaoReveal(state, state.slot),
     eth1_data: node.mainchainMonitor.getBeaconBlockRef(),
     signature: ValidatorSig(), # we need the rest of the block first!
     body: blockBody)

beacon_chain/conf.nim

@@ -2,7 +2,7 @@ import
   os, options,
   confutils/defs, chronicles/options as chroniclesOptions,
   json_serialization,
-  spec/[crypto, datatypes], randao, time
+  spec/[crypto, datatypes], time
 
 export
   json_serialization
@@ -20,7 +20,6 @@ type
 
   PrivateValidatorData* = object
     privKey*: ValidatorPrivKey
-    randao*: Randao
 
   BeaconNodeConf* = object
     logLevel* {.
@@ -81,13 +80,9 @@ proc readFileBytes(path: string): seq[byte] =
 proc loadPrivKey*(p: ValidatorKeyPath): ValidatorPrivKey =
   ValidatorPrivKey.init(readFileBytes(string(p) & ".privkey"))
 
-proc loadRandao*(p: ValidatorKeyPath): Randao =
-  initRandao(readFileBytes(string(p) & ".randao"))
-
 proc parseCmdArg*(T: type ValidatorKeyPath, input: TaintedString): T =
   result = T(input)
   discard loadPrivKey(result)
-  discard loadRandao(result)
 
 template mustBeFilePath(input: TaintedString) =
   if not fileExists(string input):

beacon_chain/randao.nim

@@ -1,49 +0,0 @@
-import spec/[digest, helpers]
-
-type Randao* = object
-  seed*: Eth2Digest
-
-const MaxRandaoLevels = 10000 # TODO: This number is arbitrary
-
-proc initRandao*(seed: Eth2Digest): Randao =
-  result.seed = seed
-
-proc initRandao*(bytes: openarray[byte]): Randao =
-  if bytes.len != sizeof(Eth2Digest):
-    raise newException(Exception, "Wrong randao size")
-  var s: Eth2Digest
-  s.data[0 .. ^1] = bytes
-  initRandao(s)
-
-proc initialCommitment*(r: Randao): Eth2Digest =
-  repeatHash(r.seed, MaxRandaoLevels)
-
-proc reveal*(r: Randao, commitment: Eth2Digest): Eth2Digest =
-  if commitment == r.seed:
-    raise newException(Exception, "Randao: cannot reveal for seed")
-  result = r.seed
-  for i in 0 .. MaxRandaoLevels:
-    let h = eth2hash(result.data)
-    if h == commitment:
-      return
-    result = h
-
-  raise newException(Exception, "Randao: commitment not found")
-
-when isMainModule:
-  import times, nimcrypto
-  var seed: Eth2Digest
-  let r = initRandao(seed)
-
-  var s = epochTime()
-  var ic = r.initialCommitment()
-  var e = epochTime()
-  echo "initialCommitment: ", ic
-  echo "Took time: ", e - s
-  s = epochTime()
-  let rev = r.reveal(ic)
-  e = epochTime()
-  echo "reveal: ", rev
-  echo "Took time: ", e - s
-
-  echo r.reveal(eth2hash([1.byte, 2, 3])) # Should raise

beacon_chain/spec/helpers.nim

@@ -54,18 +54,6 @@ func get_new_recent_block_roots*(old_block_roots: seq[Eth2Digest],
   for _ in 0 ..< min(d, old_block_roots.len):
     result.add parent_hash
 
-# TODO remove; cascades through randao.nim, validator_pool.nim, etc
-func repeat_hash*(v: Eth2Digest, n: SomeInteger): Eth2Digest =
-  # Spec version:
-  # if n == 0: v
-  # else: repeat_hash(eth2hash(v.data), n - 1)
-  # Nim is pretty bad at recursion though (max 2k levels / no tco), so:
-  result = v
-  var n = n
-  while n != 0:
-    result = eth2hash(result.data)
-    dec n
-
 func ceil_div8*(v: int): int = (v + 7) div 8 # TODO use a proper bitarray!
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.2.0/specs/core/0_beacon-chain.md#integer_squareroot

beacon_chain/state_transition.nim

@@ -39,60 +39,49 @@ func flatten[T](v: openArray[seq[T]]): seq[T] =
   # TODO not in nim - doh.
   for x in v: result.add x
 
-proc verifyProposerSignature(state: BeaconState, blck: BeaconBlock): bool =
+# https://github.com/ethereum/eth2.0-specs/blob/v0.2.0/specs/core/0_beacon-chain.md#proposer-signature
+func verifyProposerSignature(state: BeaconState, blck: BeaconBlock): bool =
   ## When creating a block, the proposer will sign a version of the block that
   ## doesn't contain the data (chicken and egg), then add the signature to that
   ## block. Here, we check that the signature is correct by repeating the same
   ## process.
-  ##
+  var blck_without_signature = blck
-  ## https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#proposer-signature
+  blck_without_signature.signature = ValidatorSig()
-  var blck_without_sig = blck
-  blck_without_sig.signature = ValidatorSig()
 
   let
     signed_data = ProposalSignedData(
       slot: state.slot,
       shard: BEACON_CHAIN_SHARD_NUMBER,
-      block_root: hash_tree_root_final(blck_without_sig)
+      block_root: hash_tree_root_final(blck_without_signature)
     )
-    proposal_hash = hash_tree_root_final(signed_data)
+    proposal_root = hash_tree_root_final(signed_data)
     proposer_index = get_beacon_proposer_index(state, state.slot)
 
   bls_verify(
     state.validator_registry[proposer_index].pubkey,
-    proposal_hash.data, blck.signature,
+    proposal_root.data, blck.signature,
-    get_domain(state.fork, slot_to_epoch(state.slot), DOMAIN_PROPOSAL))
+    get_domain(state.fork, get_current_epoch(state), DOMAIN_PROPOSAL))
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.2.0/specs/core/0_beacon-chain.md#randao
 proc processRandao(
     state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags): bool =
-  ## When a validator signs up, they will include a hash number together with
-  ## the deposit - the randao_commitment. The commitment is formed by hashing
-  ## a secret value N times.
-  ## The first time the proposer proposes a block, they will hash their secret
-  ## value N-1 times, and provide the reuslt as "reveal" - now everyone else can
-  ## verify that the reveal matches the commitment by hashing it once.
-  ## The next time the proposer proposes, they will reveal the secret value
-  ## hashed N-2 times and so on, and everyone will verify that it matches N-1.
-  ## The previous reveal has now become the commitment!
-  ##
-  ## Effectively, the block proposer can only reveal N-1 times, so better pick
-  ## a large N!
-  ##
-  ## https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#randao
   let
     proposer_index = get_beacon_proposer_index(state, state.slot)
     proposer = addr state.validator_registry[proposer_index]
 
   if skipValidation notin flags:
-    # Check that proposer commit and reveal match
+    if not bls_verify(
-    # TODO re-enable if appropriate
+      proposer.pubkey,
-    #if expected != proposer.randao_commitment:
+      int_to_bytes32(get_current_epoch(state)),
-    #  notice "Randao reveal mismatch", reveal = blck.randao_reveal,
+      blck.randao_reveal,
-    #                                   layers = proposer.randao_layers,
+      get_domain(state.fork, get_current_epoch(state), DOMAIN_RANDAO)):
-    #                                   commitment = proposer.randao_commitment,
+
-    #                                   expected
+      notice "Randao mismatch", proposer_pubkey = proposer.pubkey,
-    #  return false
+                                message = get_current_epoch(state),
-    discard
+                                signature = blck.randao_reveal,
+                                slot = state.slot,
+                                blck_slot = blck.slot
+      return false
 
   # Update state and proposer now that we're alright
   let
@@ -102,7 +91,7 @@ proc processRandao(
   for i, b in state.latest_randao_mixes[mix].data:
     state.latest_randao_mixes[mix].data[i] = b xor rr[i]
 
-  return true
+  true
 
 func processDepositRoot(state: var BeaconState, blck: BeaconBlock) =
   ## https://github.com/ethereum/eth2.0-specs/blob/master/specs/core/0_beacon-chain.md#eth1-data
@@ -359,13 +348,12 @@ proc process_ejections(state: var BeaconState) =
         state.validator_balances[index] < EJECTION_BALANCE:
       exit_validator(state, index.ValidatorIndex)
 
+# https://github.com/ethereum/eth2.0-specs/blob/v0.2.0/specs/core/0_beacon-chain.md#per-slot-processing
 func processSlot(state: var BeaconState, previous_block_root: Eth2Digest) =
   ## Time on the beacon chain moves in slots. Every time we make it to a new
   ## slot, a proposer creates a block to represent the state of the beacon
   ## chain at that time. In case the proposer is missing, it may happen that
   ## the no block is produced during the slot.
-  ##
-  ## https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#per-slot-processing
   state.slot += 1
   state.latest_block_roots[(state.slot - 1) mod LATEST_BLOCK_ROOTS_LENGTH] =
     previous_block_root
@@ -380,6 +368,7 @@ proc processBlock(
   # TODO when there's a failure, we should reset the state!
   # TODO probably better to do all verification first, then apply state changes
 
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.2.0/specs/core/0_beacon-chain.md#slot-1
   if not (blck.slot == state.slot):
     notice "Unexpected block slot number",
       blockSlot = blck.slot,

beacon_chain/validator_pool.nim

@@ -1,7 +1,7 @@
 import
   tables, random,
   chronos,
-  spec/[datatypes, crypto, digest, helpers], randao, ssz
+  spec/[datatypes, crypto, digest, helpers], ssz
 
 type
   ValidatorKind = enum
@@ -15,7 +15,6 @@ type
     case kind: ValidatorKind
     of inProcess:
       privKey: ValidatorPrivKey
-      randaoSecret: Randao
     else:
       connection: ValidatorConnection
 
@@ -31,12 +30,10 @@ template count*(pool: ValidatorPool): int =
 proc addLocalValidator*(pool: var ValidatorPool,
                         idx: int,
                         pubKey: ValidatorPubKey,
-                        privKey: ValidatorPrivKey,
+                        privKey: ValidatorPrivKey) =
-                        randaoSecret: Randao) =
   let v = AttachedValidator(idx: idx,
                             kind: inProcess,
-                            privKey: privKey,
+                            privKey: privKey)
-                            randaoSecret: randaoSecret)
   pool.validators[pubKey] = v
 
 proc getValidator*(pool: ValidatorPool,
@@ -74,25 +71,13 @@ proc signAttestation*(v: AttachedValidator,
     # send RPC
     discard
 
-proc randaoReveal*(v: AttachedValidator, commitment: Eth2Digest): Future[Eth2Digest] {.async.} =
+func genRandaoReveal*(k: ValidatorPrivKey, state: BeaconState, slot: SlotNumber):
-  if v.kind == inProcess:
-    result = v.randaoSecret.reveal(commitment)
-  else:
-    # TODO:
-    # send RPC
-    discard
-
-# TODO move elsewhere when something else wants this utility function
-func int_to_bytes32(x: uint64) : array[32, byte] =
-  for i in 0 ..< 8:
-    result[31 - i] = byte((x shr i*8) and 0xff)
-
-func genRandaoReveal*(k: ValidatorPrivKey, state: BeaconState):
     ValidatorSig =
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.1/specs/core/0_beacon-chain.md#randao
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.2.0/specs/core/0_beacon-chain.md#randao
-  bls_sign(k, int_to_bytes32(get_current_epoch(state)),
+  assert slot > state.slot
-           get_domain(state.fork, get_current_epoch(state), DOMAIN_RANDAO))
+  bls_sign(k, int_to_bytes32(slot_to_epoch(slot)),
+    get_domain(state.fork, slot_to_epoch(slot), DOMAIN_RANDAO))
 
-func genRandaoReveal*(v: AttachedValidator, state: BeaconState):
+func genRandaoReveal*(v: AttachedValidator, state: BeaconState, slot: SlotNumber):
     ValidatorSig =
-  genRandaoReveal(v.privKey, state)
+  genRandaoReveal(v.privKey, state, slot)

tests/testutil.nim

@@ -100,7 +100,7 @@ proc addBlock*(
       slot: state.slot + 1,
       parent_root: previous_block_root,
       state_root: Eth2Digest(), # we need the new state first
-      randao_reveal: privKey.genRandaoReveal(state),
+      randao_reveal: privKey.genRandaoReveal(state, state.slot + 1),
       eth1_data: Eth1Data(), # TODO
       signature: ValidatorSig(), # we need the rest of the block first!
       body: body