slightly update/rename verify_merkle_branch(...) to 0.8.2 is_valid_merkle_branch(...); mark check_attestation(...), get_active_validator_indices(...), get_seed(...), and BeaconBlockBody as 0.8.2; update compute_domain(...) 0.8.2 by reversing field order (#356)

beacon_chain/spec/beaconstate.nim

@@ -11,21 +11,21 @@ import
   ../extras, ../ssz, ../beacon_node_types,
   ./crypto, ./datatypes, ./digest, ./helpers, ./validator
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#verify_merkle_branch
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.2/specs/core/0_beacon-chain.md#is_valid_merkle_branch
-func verify_merkle_branch(leaf: Eth2Digest, proof: openarray[Eth2Digest], depth: uint64, index: uint64, root: Eth2Digest): bool =
+func is_valid_merkle_branch(leaf: Eth2Digest, branch: openarray[Eth2Digest], depth: uint64, index: uint64, root: Eth2Digest): bool =
-  ## Verify that the given ``leaf`` is on the merkle branch ``proof``
+  ## Check if ``leaf`` at ``index`` verifies against the Merkle ``root`` and
-  ## starting with the given ``root``.
+  ## ``branch``.
   var
     value = leaf
     buf: array[64, byte]
 
   for i in 0 ..< depth.int:
     if (index div (1'u64 shl i)) mod 2 != 0:
-      buf[0..31] = proof[i.int].data
+      buf[0..31] = branch[i.int].data
       buf[32..63] = value.data
     else:
       buf[0..31] = value.data
-      buf[32..63] = proof[i.int].data
+      buf[32..63] = branch[i.int].data
     value = eth2hash(buf)
   value == root
 
@@ -53,7 +53,7 @@ func process_deposit*(
 
   # Verify the Merkle branch
   # TODO enable this check, but don't use doAssert
-  if not verify_merkle_branch(
+  if not is_valid_merkle_branch(
     hash_tree_root(deposit.data),
      deposit.proof,
      DEPOSIT_CONTRACT_TREE_DEPTH,
@@ -466,8 +466,7 @@ func get_indexed_attestation*(state: BeaconState, attestation: Attestation,
     signature: attestation.signature,
   )
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.1/specs/core/0_beacon-chain.md#attestations
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.2/specs/core/0_beacon-chain.md#attestations
-
 proc check_attestation*(
     state: BeaconState, attestation: Attestation, flags: UpdateFlags,
     stateCache: var StateCache): bool =

beacon_chain/spec/datatypes.nim

@@ -53,7 +53,7 @@ else:
   {.fatal: "Preset \"" & const_preset ".nim\" is not supported.".}
 
 const
-  SPEC_VERSION* = "0.8.1" ## \
+  SPEC_VERSION* = "0.8.2" ## \
   ## Spec version we're aiming to be compatible with, right now
   ## TODO: improve this scheme once we can negotiate versions in protocol
 
@@ -239,11 +239,13 @@ type
     body_root*: Eth2Digest
     signature*: ValidatorSig
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#beaconblockbody
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.2/specs/core/0_beacon-chain.md#beaconblockbody
   BeaconBlockBody* = object
     randao_reveal*: ValidatorSig
     eth1_data*: Eth1Data
     graffiti*: Eth2Digest
+
+    # Each of these is a length-bounded list, but enforcing that's elsewhere
     proposer_slashings*: seq[ProposerSlashing]
     attester_slashings*: seq[AttesterSlashing]
     attestations*: seq[Attestation]

beacon_chain/spec/helpers.nim

@@ -73,9 +73,10 @@ func is_active_validator*(validator: Validator, epoch: Epoch): bool =
   validator.activation_epoch <= epoch and epoch < validator.exit_epoch
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#get_active_validator_indices
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.2/specs/core/0_beacon-chain.md#get_active_validator_indices
 func get_active_validator_indices*(state: BeaconState, epoch: Epoch):
     seq[ValidatorIndex] =
-  # Get active validator indices at ``epoch``.
+  # Return the sequence of active validator indices at ``epoch``.
   for idx, val in state.validators:
     if is_active_validator(val, epoch):
       result.add idx.ValidatorIndex
@@ -106,7 +107,6 @@ func get_randao_mix*(state: BeaconState,
     ## LATEST_RANDAO_MIXES_LENGTH, current_epoch].
     state.randao_mixes[epoch mod LATEST_RANDAO_MIXES_LENGTH]
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.7.1/specs/core/0_beacon-chain.md#bytes_to_int
 func bytes_to_int*(data: openarray[byte]): uint64 =
   doAssert data.len == 8
 
@@ -115,7 +115,6 @@ func bytes_to_int*(data: openarray[byte]): uint64 =
   for i in countdown(7, 0):
     result = result * 256 + data[i]
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#int_to_bytes1-int_to_bytes2-
 # Have 1, 4, 8, and 32-byte versions. 1+ more and maybe worth metaprogramming.
 func int_to_bytes32*(x: uint64): array[32, byte] =
   ## Little-endian data representation
@@ -145,12 +144,12 @@ func int_to_bytes4*(x: uint64): array[4, byte] =
   result[2] = ((x shr 16) and 0xff).byte
   result[3] = ((x shr 24) and 0xff).byte
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#bls_domain
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.2/specs/core/0_beacon-chain.md#compute_domain
 func compute_domain(domain_type: DomainType, fork_version: array[4, byte]):
     uint64 =
   var buf: array[8, byte]
-  buf[0..3] = fork_version
+  buf[0..3] = int_to_bytes4(domain_type.uint64)
-  buf[4..7] = int_to_bytes4(domain_type.uint64)
+  buf[4..7] = fork_version
   bytes_to_int(buf)
 
 # https://github.com/ethereum/eth2.0-specs/blob/v0.8.2/specs/core/0_beacon-chain.md#get_domain
@@ -169,7 +168,7 @@ func get_domain*(
 func get_domain*(state: BeaconState, domain_type: DomainType): Domain =
   get_domain(state, domain_type, get_current_epoch(state))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.6.3/specs/core/0_beacon-chain.md#get_seed
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.2/specs/core/0_beacon-chain.md#get_seed
 func get_seed*(state: BeaconState, epoch: Epoch): Eth2Digest =
   # Generate a seed for the given ``epoch``.