From 700e7d921b573917702ee9b91084ac1af8dca1e8 Mon Sep 17 00:00:00 2001
From: Dustin Brody <tersec@users.noreply.github.com>
Date: Thu, 24 Oct 2019 13:36:36 +0000
Subject: [PATCH] update to beacon chain phase 0 spec version 0.8.4; no
 substantive changes (#494)

---
 beacon_chain/beacon_node.nim                  |  2 +-
 beacon_chain/fork_choice.nim                  |  2 +-
 beacon_chain/interop.nim                      |  2 +-
 beacon_chain/spec/beaconstate.nim             | 38 +++++++--------
 beacon_chain/spec/crypto.nim                  |  6 +--
 beacon_chain/spec/datatypes.nim               | 48 +++++++++----------
 beacon_chain/spec/digest.nim                  |  2 +-
 beacon_chain/spec/helpers.nim                 | 22 ++++-----
 beacon_chain/spec/presets/mainnet.nim         | 16 +++----
 beacon_chain/spec/presets/minimal.nim         | 14 +++---
 beacon_chain/spec/state_transition_block.nim  | 16 +++----
 beacon_chain/spec/state_transition_epoch.nim  | 40 ++++++++--------
 .../spec/state_transition_helpers.nim         |  2 +-
 beacon_chain/spec/validator.nim               | 16 +++----
 beacon_chain/state_transition.nim             | 10 ++--
 beacon_chain/time.nim                         |  2 +-
 16 files changed, 119 insertions(+), 119 deletions(-)

diff --git a/beacon_chain/beacon_node.nim b/beacon_chain/beacon_node.nim
index 40df9db69..1f44eacb9 100644
--- a/beacon_chain/beacon_node.nim
+++ b/beacon_chain/beacon_node.nim
@@ -567,7 +567,7 @@ proc handleAttestations(node: BeaconNode, head: BlockRef, slot: Slot) =
   # We need to run attestations exactly for the slot that we're attesting to.
   # In case blocks went missing, this means advancing past the latest block
   # using empty slots as fillers.
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/validator/0_beacon-chain-validator.md#validator-assignments
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/validator/0_beacon-chain-validator.md#validator-assignments
   # TODO we could cache the validator assignment since it's valid for the entire
   #      epoch since it doesn't change, but that has to be weighed against
   #      the complexity of handling forks correctly - instead, we use an adapted
diff --git a/beacon_chain/fork_choice.nim b/beacon_chain/fork_choice.nim
index ca138b9af..89bfa9e86 100644
--- a/beacon_chain/fork_choice.nim
+++ b/beacon_chain/fork_choice.nim
@@ -12,7 +12,7 @@ proc get_ancestor(blck: BlockRef, slot: Slot): BlockRef =
   else:
     get_ancestor(blck.parent, slot)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_fork-choice.md
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_fork-choice.md
 # The structure of this code differs from the spec since we use a different
 # strategy for storing states and justification points - it should nonetheless
 # be close in terms of functionality.
diff --git a/beacon_chain/interop.nim b/beacon_chain/interop.nim
index 2ae584f30..ceb31deb2 100644
--- a/beacon_chain/interop.nim
+++ b/beacon_chain/interop.nim
@@ -41,7 +41,7 @@ const eth1BlockHash* = block:
   x
 
 func makeWithdrawalCredentials*(k: ValidatorPubKey): Eth2Digest =
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_deposit-contract.md#withdrawal-credentials
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_deposit-contract.md#withdrawal-credentials
   var bytes = eth2hash(k.getBytes())
   bytes.data[0] = BLS_WITHDRAWAL_PREFIX.uint8
   bytes
diff --git a/beacon_chain/spec/beaconstate.nim b/beacon_chain/spec/beaconstate.nim
index 2a9a9b395..7d8b35dad 100644
--- a/beacon_chain/spec/beaconstate.nim
+++ b/beacon_chain/spec/beaconstate.nim
@@ -11,7 +11,7 @@ import
   ../extras, ../ssz,
   ./crypto, ./datatypes, ./digest, ./helpers, ./validator
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#is_valid_merkle_branch
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#is_valid_merkle_branch
 func is_valid_merkle_branch(leaf: Eth2Digest, branch: openarray[Eth2Digest], depth: uint64, index: uint64, root: Eth2Digest): bool =
   ## Check if ``leaf`` at ``index`` verifies against the Merkle ``root`` and
   ## ``branch``.
@@ -29,13 +29,13 @@ func is_valid_merkle_branch(leaf: Eth2Digest, branch: openarray[Eth2Digest], dep
     value = eth2hash(buf)
   value == root
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#increase_balance
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#increase_balance
 func increase_balance*(
     state: var BeaconState, index: ValidatorIndex, delta: Gwei) =
   # Increase the validator balance at index ``index`` by ``delta``.
   state.balances[index] += delta
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#decrease_balance
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#decrease_balance
 func decrease_balance*(
     state: var BeaconState, index: ValidatorIndex, delta: Gwei) =
   ## Decrease the validator balance at index ``index`` by ``delta``, with
@@ -102,13 +102,13 @@ func process_deposit*(
 
   true
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#compute_activation_exit_epoch
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compute_activation_exit_epoch
 func compute_activation_exit_epoch*(epoch: Epoch): Epoch =
   ## Return the epoch during which validator activations and exits initiated in
   ## ``epoch`` take effect.
   epoch + 1 + ACTIVATION_EXIT_DELAY
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_validator_churn_limit
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_validator_churn_limit
 func get_validator_churn_limit(state: BeaconState): uint64 =
   # Return the validator churn limit for the current epoch.
   let active_validator_indices =
@@ -116,7 +116,7 @@ func get_validator_churn_limit(state: BeaconState): uint64 =
   max(MIN_PER_EPOCH_CHURN_LIMIT,
     len(active_validator_indices) div CHURN_LIMIT_QUOTIENT).uint64
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#initiate_validator_exit
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#initiate_validator_exit
 func initiate_validator_exit*(state: var BeaconState,
                               index: ValidatorIndex) =
   # Initiate the exit of the validator with index ``index``.
@@ -146,7 +146,7 @@ func initiate_validator_exit*(state: var BeaconState,
   validator.withdrawable_epoch =
     validator.exit_epoch + MIN_VALIDATOR_WITHDRAWABILITY_DELAY
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#slash_validator
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#slash_validator
 func slash_validator*(state: var BeaconState, slashed_index: ValidatorIndex,
     stateCache: var StateCache) =
   # Slash the validator with index ``index``.
@@ -174,7 +174,7 @@ func slash_validator*(state: var BeaconState, slashed_index: ValidatorIndex,
   increase_balance(
     state, whistleblower_index, whistleblowing_reward - proposer_reward)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_compact_committees_root
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_compact_committees_root
 func get_compact_committees_root*(state: BeaconState, epoch: Epoch): Eth2Digest =
   # Return the compact committee root at ``epoch``.
 
@@ -201,7 +201,7 @@ func get_compact_committees_root*(state: BeaconState, epoch: Epoch): Eth2Digest
 
   hash_tree_root(committees)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#genesis
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#genesis
 func initialize_beacon_state_from_eth1*(
     eth1_block_hash: Eth2Digest,
     eth1_timestamp: uint64,
@@ -296,7 +296,7 @@ func get_initial_beacon_block*(state: BeaconState): BeaconBlock =
     # initialized to default values.
 
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_attestation_data_slot
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_attestation_data_slot
 func get_attestation_data_slot*(state: BeaconState,
     data: AttestationData, committee_count: uint64): Slot =
   # Return the slot corresponding to the attestation ``data``.
@@ -313,7 +313,7 @@ func get_attestation_data_slot*(state: BeaconState,
   get_attestation_data_slot(
     state, data, get_committee_count(state, data.target.epoch))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_block_root_at_slot
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_block_root_at_slot
 func get_block_root_at_slot*(state: BeaconState,
                              slot: Slot): Eth2Digest =
   # Return the block root at a recent ``slot``.
@@ -322,12 +322,12 @@ func get_block_root_at_slot*(state: BeaconState,
   doAssert slot < state.slot
   state.block_roots[slot mod SLOTS_PER_HISTORICAL_ROOT]
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_block_root
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_block_root
 func get_block_root*(state: BeaconState, epoch: Epoch): Eth2Digest =
   # Return the block root at the start of a recent ``epoch``.
   get_block_root_at_slot(state, compute_start_slot_of_epoch(epoch))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_total_balance
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_total_balance
 func get_total_balance*(state: BeaconState, validators: auto): Gwei =
   ## Return the combined effective balance of the ``indices``. (1 Gwei minimum
   ## to avoid divisions by zero.)
@@ -336,7 +336,7 @@ func get_total_balance*(state: BeaconState, validators: auto): Gwei =
   )
 
 # XXX: Move to state_transition_epoch.nim?
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#registry-updates
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#registry-updates
 func process_registry_updates*(state: var BeaconState) =
   ## Process activation eligibility and ejections
   ## Try to avoid caching here, since this could easily become undefined
@@ -376,7 +376,7 @@ func process_registry_updates*(state: var BeaconState) =
       validator.activation_epoch =
         compute_activation_exit_epoch(get_current_epoch(state))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#is_valid_indexed_attestation
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#is_valid_indexed_attestation
 proc is_valid_indexed_attestation*(
     state: BeaconState, indexed_attestation: IndexedAttestation): bool =
   ## Check if ``indexed_attestation`` has valid indices and signature.
@@ -437,7 +437,7 @@ proc is_valid_indexed_attestation*(
   if not result:
     notice "indexed attestation: signature verification failure"
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_attesting_indices
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_attesting_indices
 func get_attesting_indices*(state: BeaconState,
                             data: AttestationData,
                             bits: CommitteeValidatorsBits,
@@ -460,7 +460,7 @@ func get_attesting_indices_seq*(state: BeaconState,
   toSeq(items(get_attesting_indices(
     state, attestation_data, bits, cache)))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_indexed_attestation
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_indexed_attestation
 func get_indexed_attestation*(state: BeaconState, attestation: Attestation,
     stateCache: var StateCache): IndexedAttestation =
   # Return the indexed attestation corresponding to ``attestation``.
@@ -499,7 +499,7 @@ func get_indexed_attestation*(state: BeaconState, attestation: Attestation,
     signature: attestation.signature,
   )
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#attestations
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#attestations
 proc check_attestation*(
     state: BeaconState, attestation: Attestation, flags: UpdateFlags,
     stateCache: var StateCache): bool =
@@ -656,7 +656,7 @@ proc makeAttestationData*(
   ## `state` is the state corresponding to the `beacon_block_root` advanced to
   ## the slot we're attesting to.
 
-  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/validator/0_beacon-chain-validator.md#construct-attestation
+  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/validator/0_beacon-chain-validator.md#construct-attestation
 
   let
     current_epoch = get_current_epoch(state)
diff --git a/beacon_chain/spec/crypto.nim b/beacon_chain/spec/crypto.nim
index cea544976..2ee234514 100644
--- a/beacon_chain/spec/crypto.nim
+++ b/beacon_chain/spec/crypto.nim
@@ -162,11 +162,11 @@ proc combine*[T](x: var BlsValue[T], other: BlsValue[T]) =
   doAssert x.kind == Real and other.kind == Real
   x.blsValue.combine(other.blsValue)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/bls_signature.md#bls_aggregate_pubkeys
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/bls_signature.md#bls_aggregate_pubkeys
 func bls_aggregate_pubkeys*(keys: openArray[ValidatorPubKey]): ValidatorPubKey =
   keys.combine()
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/bls_signature.md#bls_verify
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/bls_signature.md#bls_verify
 func bls_verify*(
     pubkey: ValidatorPubKey, msg: openArray[byte], sig: ValidatorSig,
     domain: Domain): bool =
@@ -182,7 +182,7 @@ func bls_verify*(
   else:
     sig.verify(msg, domain, pubkey)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/bls_signature.md#bls_verify_multiple
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/bls_signature.md#bls_verify_multiple
 proc bls_verify_multiple*(
     pubkeys: seq[ValidatorPubKey], message_hashes: openArray[Eth2Digest],
     sig: ValidatorSig, domain: Domain): bool =
diff --git a/beacon_chain/spec/datatypes.nim b/beacon_chain/spec/datatypes.nim
index 0e5d5952c..877827714 100644
--- a/beacon_chain/spec/datatypes.nim
+++ b/beacon_chain/spec/datatypes.nim
@@ -53,13 +53,13 @@ else:
   {.fatal: "Preset \"" & const_preset ".nim\" is not supported.".}
 
 const
-  SPEC_VERSION* = "0.8.3" ## \
+  SPEC_VERSION* = "0.8.4" ## \
   ## Spec version we're aiming to be compatible with, right now
   ## TODO: improve this scheme once we can negotiate versions in protocol
 
   # Initial values
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#initial-values
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#initial-values
   GENESIS_EPOCH* = (GENESIS_SLOT.uint64 div SLOTS_PER_EPOCH).Epoch ##\
   ## compute_epoch_of_slot(GENESIS_SLOT)
 
@@ -86,7 +86,7 @@ type
 
   BitList*[maxLen: static int] = distinct BitSeq
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#proposerslashing
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#proposerslashing
   ProposerSlashing* = object
     proposer_index*: uint64 ##\
     ## Proposer index
@@ -97,7 +97,7 @@ type
     header_2*: BeaconBlockHeader ##\
     # Second block header
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#attesterslashing
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#attesterslashing
   AttesterSlashing* = object
     attestation_1*: IndexedAttestation ## \
     ## First attestation
@@ -106,7 +106,7 @@ type
 
   CustodyBitIndices* = List[uint64, MAX_VALIDATORS_PER_COMMITTEE]
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#indexedattestation
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#indexedattestation
   IndexedAttestation* = object
     custody_bit_0_indices*: CustodyBitIndices ##\
     ## Indices with custody bit equal to 0
@@ -119,19 +119,19 @@ type
 
   CommitteeValidatorsBits* = BitList[MAX_VALIDATORS_PER_COMMITTEE]
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#attestation
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#attestation
   Attestation* = object
     aggregation_bits*: CommitteeValidatorsBits
     data*: AttestationData
     custody_bits*: CommitteeValidatorsBits
     signature*: ValidatorSig
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#checkpoint
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#checkpoint
   Checkpoint* = object
     epoch*: Epoch
     root*: Eth2Digest
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#AttestationData
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#AttestationData
   AttestationData* = object
     # LMD GHOST vote
     beacon_block_root*: Eth2Digest
@@ -143,21 +143,21 @@ type
     # Crosslink vote
     crosslink*: Crosslink
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#attestationdataandcustodybit
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#attestationdataandcustodybit
   AttestationDataAndCustodyBit* = object
     data*: AttestationData
 
     custody_bit*: bool ##\
     ## Challengeable bit (SSZ-bool, 1 byte) for the custody of crosslink data
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#deposit
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#deposit
   Deposit* = object
     proof*: array[DEPOSIT_CONTRACT_TREE_DEPTH + 1, Eth2Digest] ##\
     ## Merkle path to deposit data list root
 
     data*: DepositData
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#depositdata
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#depositdata
   DepositData* = object
     pubkey*: ValidatorPubKey ##\
     ## BLS pubkey
@@ -171,7 +171,7 @@ type
     signature*: ValidatorSig ##\
     ## Container self-signature
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#voluntaryexit
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#voluntaryexit
   VoluntaryExit* = object
     epoch*: Epoch ##\
     ## Earliest epoch when voluntary exit can be processed
@@ -179,7 +179,7 @@ type
     validator_index*: uint64
     signature*: ValidatorSig
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#transfer
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#transfer
   Transfer* = object
     sender*: uint64 ##\
     ## Sender index
@@ -203,7 +203,7 @@ type
     signature*: ValidatorSig ##\
     ## Signature checked against withdrawal pubkey
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beaconblock
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beaconblock
   BeaconBlock* = object
     ## For each slot, a proposer is chosen from the validator pool to propose
     ## a new block. Once the block as been proposed, it is transmitted to
@@ -224,12 +224,12 @@ type
     signature*: ValidatorSig ##\
     ## Proposer signature
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#compactcommittee
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compactcommittee
   CompactCommittee* = object
     pubkeys*: seq[ValidatorPubKey]
     compact_validators*: seq[uint64]
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beaconblockheader
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beaconblockheader
   BeaconBlockHeader* = object
     slot*: Slot
     parent_root*: Eth2Digest
@@ -237,7 +237,7 @@ type
     body_root*: Eth2Digest
     signature*: ValidatorSig
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beaconblockbody
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beaconblockbody
   BeaconBlockBody* = object
     randao_reveal*: ValidatorSig
     eth1_data*: Eth1Data
@@ -249,7 +249,7 @@ type
     voluntary_exits*: seq[VoluntaryExit]
     transfers*: seq[Transfer]
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beaconstate
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beaconstate
   BeaconState* = object
     # Versioning
     genesis_time*: uint64
@@ -320,7 +320,7 @@ type
     current_justified_checkpoint*: Checkpoint
     finalized_checkpoint*: Checkpoint
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#validator
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#validator
   Validator* = object
     pubkey*: ValidatorPubKey
 
@@ -343,7 +343,7 @@ type
     withdrawable_epoch*: Epoch ##\
     ## When validator can withdraw or transfer funds
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#crosslink
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#crosslink
   Crosslink* = object
     shard*: Shard
     parent_root*: Eth2Digest
@@ -354,19 +354,19 @@ type
 
     data_root*: Eth2Digest
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#pendingattestation
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#pendingattestation
   PendingAttestation* = object
     aggregation_bits*: CommitteeValidatorsBits
     data*: AttestationData
     inclusion_delay*: uint64
     proposer_index*: uint64
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#historicalbatch
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#historicalbatch
   HistoricalBatch* = object
     block_roots* : array[SLOTS_PER_HISTORICAL_ROOT, Eth2Digest]
     state_roots* : array[SLOTS_PER_HISTORICAL_ROOT, Eth2Digest]
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#fork
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#fork
   Fork* = object
     # TODO: Spec introduced an alias for Version = array[4, byte]
     #       and a default parameter to compute_domain
@@ -376,7 +376,7 @@ type
     epoch*: Epoch ##\
     ## Epoch of latest fork
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#eth1data
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#eth1data
   Eth1Data* = object
     deposit_root*: Eth2Digest ##\
     ## Root of the deposit tree
diff --git a/beacon_chain/spec/digest.nim b/beacon_chain/spec/digest.nim
index 698237d49..6361d4311 100644
--- a/beacon_chain/spec/digest.nim
+++ b/beacon_chain/spec/digest.nim
@@ -7,7 +7,7 @@
 
 # Serenity hash function / digest
 #
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#hash
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#hash
 #
 # In Phase 0 the beacon chain is deployed with SHA256 (SHA2-256).
 # Note that is is different from Keccak256 (often mistakenly called SHA3-256)
diff --git a/beacon_chain/spec/helpers.nim b/beacon_chain/spec/helpers.nim
index 5a7f904bf..e297ad57d 100644
--- a/beacon_chain/spec/helpers.nim
+++ b/beacon_chain/spec/helpers.nim
@@ -15,7 +15,7 @@ import
   # Internal
   ./datatypes, ./digest
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#integer_squareroot
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#integer_squareroot
 func integer_squareroot*(n: SomeInteger): SomeInteger =
   # Return the largest integer ``x`` such that ``x**2 <= n``.
   doAssert n >= 0'u64
@@ -63,7 +63,7 @@ func merkle_root*(values: openArray[Eth2Digest]): Eth2Digest =
 
   o[1]
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#compute_epoch_of_slot
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compute_epoch_of_slot
 func compute_epoch_of_slot*(slot: Slot|uint64): Epoch =
   # Return the epoch number of the given ``slot``.
   (slot div SLOTS_PER_EPOCH).Epoch
@@ -71,17 +71,17 @@ func compute_epoch_of_slot*(slot: Slot|uint64): Epoch =
 template epoch*(slot: Slot): Epoch =
   compute_epoch_of_slot(slot)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#compute_start_slot_of_epoch
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compute_start_slot_of_epoch
 func compute_start_slot_of_epoch*(epoch: Epoch): Slot =
   # Return the start slot of ``epoch``.
   (epoch * SLOTS_PER_EPOCH).Slot
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#is_active_validator
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#is_active_validator
 func is_active_validator*(validator: Validator, epoch: Epoch): bool =
   ### Check if ``validator`` is active
   validator.activation_epoch <= epoch and epoch < validator.exit_epoch
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_active_validator_indices
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_active_validator_indices
 func get_active_validator_indices*(state: BeaconState, epoch: Epoch):
     seq[ValidatorIndex] =
   # Return the sequence of active validator indices at ``epoch``.
@@ -89,7 +89,7 @@ func get_active_validator_indices*(state: BeaconState, epoch: Epoch):
     if is_active_validator(val, epoch):
       result.add idx.ValidatorIndex
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_committee_count
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_committee_count
 func get_committee_count*(state: BeaconState, epoch: Epoch): uint64 =
   # Return the number of committees at ``epoch``.
   let active_validator_indices = get_active_validator_indices(state, epoch)
@@ -101,13 +101,13 @@ func get_committee_count*(state: BeaconState, epoch: Epoch): uint64 =
   # Otherwise, get_crosslink_committee(...) cannot access some committees.
   doAssert SHARD_COUNT >= result
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_current_epoch
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_current_epoch
 func get_current_epoch*(state: BeaconState): Epoch =
   # Return the current epoch.
   doAssert state.slot >= GENESIS_SLOT, $state.slot
   compute_epoch_of_slot(state.slot)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_randao_mix
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_randao_mix
 func get_randao_mix*(state: BeaconState,
                      epoch: Epoch): Eth2Digest =
     ## Returns the randao mix at a recent ``epoch``.
@@ -148,14 +148,14 @@ 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/v0.8.3/specs/core/0_beacon-chain.md#compute_domain
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compute_domain
 func compute_domain*(
     domain_type: DomainType,
     fork_version: array[4, byte] = [0'u8, 0, 0, 0]): Domain =
   result[0..3] = int_to_bytes4(domain_type.uint64)
   result[4..7] = fork_version
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_domain
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_domain
 func get_domain*(
     state: BeaconState, domain_type: DomainType, message_epoch: Epoch): Domain =
   ## Return the signature domain (fork version concatenated with domain type)
@@ -171,7 +171,7 @@ 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/v0.8.3/specs/core/0_beacon-chain.md#get_seed
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_seed
 func get_seed*(state: BeaconState, epoch: Epoch): Eth2Digest =
   # Generate a seed for the given ``epoch``.
 
diff --git a/beacon_chain/spec/presets/mainnet.nim b/beacon_chain/spec/presets/mainnet.nim
index 457295fd9..83db343fc 100644
--- a/beacon_chain/spec/presets/mainnet.nim
+++ b/beacon_chain/spec/presets/mainnet.nim
@@ -25,7 +25,7 @@ type
 const
   # Misc
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#misc
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#misc
 
   SHARD_COUNT* {.intdefine.} = 1024 ##\
   ## Number of shards supported by the network - validators will jump around
@@ -53,14 +53,14 @@ const
   SHUFFLE_ROUND_COUNT* = 90
 
   # Constants (TODO: not actually configurable)
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#constants
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#constants
   BASE_REWARDS_PER_EPOCH* = 5
 
   DEPOSIT_CONTRACT_TREE_DEPTH* = 32
 
   # Gwei values
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#gwei-values
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#gwei-values
 
   MIN_DEPOSIT_AMOUNT* = 2'u64^0 * 10'u64^9 ##\
   ## Minimum amounth of ETH that can be deposited in one call - deposits can
@@ -84,12 +84,12 @@ const
 
   # Time parameters
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_fork-choice.md#time-parameters
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_fork-choice.md#time-parameters
 
   SECONDS_PER_SLOT*{.intdefine.} = 6'u64 # Compile with -d:SECONDS_PER_SLOT=1 for 6x faster slots
   ## TODO consistent time unit across projects, similar to C++ chrono?
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#time-parameters
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#time-parameters
   MIN_ATTESTATION_INCLUSION_DELAY* = 1 ##\
   ## (24 seconds)
   ## Number of slots that attestations stay in the attestation
@@ -142,7 +142,7 @@ const
 
   # Reward and penalty quotients
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#rewards-and-penalties
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#rewards-and-penalties
   BASE_REWARD_FACTOR* = 2'u64^6
   WHISTLEBLOWER_REWARD_QUOTIENT* = 2'u64^9
   PROPOSER_REWARD_QUOTIENT* = 2'u64^3
@@ -151,7 +151,7 @@ const
 
   # Max operations per block
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#max-operations-per-block
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#max-operations-per-block
   MAX_PROPOSER_SLASHINGS* = 2^4
   MAX_ATTESTER_SLASHINGS* = 2^0
   MAX_ATTESTATIONS* = 2^7
@@ -165,7 +165,7 @@ const
 type
   # Signature domains
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#signature-domain-types
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#signature-domain-types
   DomainType* {.pure.} = enum
     DOMAIN_BEACON_PROPOSER = 0
     DOMAIN_RANDAO = 1
diff --git a/beacon_chain/spec/presets/minimal.nim b/beacon_chain/spec/presets/minimal.nim
index b023830cb..a64d7d110 100644
--- a/beacon_chain/spec/presets/minimal.nim
+++ b/beacon_chain/spec/presets/minimal.nim
@@ -44,14 +44,14 @@ const
 
   # Constants
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#constants
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#constants
   # TODO "The following values are (non-configurable) constants" ...
   # Unchanged
   DEPOSIT_CONTRACT_TREE_DEPTH* = 32
 
   # Gwei values
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#gwei-values
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#gwei-values
 
   # Unchanged
   MIN_DEPOSIT_AMOUNT* = 2'u64^0 * 10'u64^9
@@ -69,12 +69,12 @@ const
 
   # Time parameters
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_fork-choice.md#time-parameters
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_fork-choice.md#time-parameters
 
   # Unchanged
   SECONDS_PER_SLOT*{.intdefine.} = 6'u64
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#time-parameters
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#time-parameters
   # Unchanged
   MIN_ATTESTATION_INCLUSION_DELAY* = 1
 
@@ -107,7 +107,7 @@ const
 
   # Reward and penalty quotients
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#rewards-and-penalties
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#rewards-and-penalties
 
   # Unchanged
   BASE_REWARD_FACTOR* = 2'u64^6
@@ -118,7 +118,7 @@ const
 
   # Max operations per block
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#max-operations-per-block
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#max-operations-per-block
 
   # Unchanged
   MAX_PROPOSER_SLASHINGS* = 2^4
@@ -132,7 +132,7 @@ const
 type
   # Signature domains
   # ---------------------------------------------------------------
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#signature-domain-types
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#signature-domain-types
   DomainType* {.pure.} = enum
     DOMAIN_BEACON_PROPOSER = 0
     DOMAIN_RANDAO = 1
diff --git a/beacon_chain/spec/state_transition_block.nim b/beacon_chain/spec/state_transition_block.nim
index 1cbc3d93a..26d9db8d8 100644
--- a/beacon_chain/spec/state_transition_block.nim
+++ b/beacon_chain/spec/state_transition_block.nim
@@ -44,7 +44,7 @@ declareGauge beacon_previous_live_validators, "Number of active validators that
 declareGauge beacon_pending_deposits, "Number of pending deposits (state.eth1_data.deposit_count - state.eth1_deposit_index)" # On block
 declareGauge beacon_processed_deposits_total, "Number of total deposits included on chain" # On block
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#block-header
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#block-header
 proc process_block_header*(
     state: var BeaconState, blck: BeaconBlock, flags: UpdateFlags,
     stateCache: var StateCache): bool =
@@ -99,7 +99,7 @@ proc process_block_header*(
 
   true
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#randao
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#randao
 proc process_randao(
     state: var BeaconState, body: BeaconBlockBody, flags: UpdateFlags,
     stateCache: var StateCache): bool =
@@ -132,21 +132,21 @@ proc process_randao(
 
   true
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#eth1-data
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#eth1-data
 func processEth1Data(state: var BeaconState, body: BeaconBlockBody) =
   state.eth1_data_votes.add body.eth1_data
   if state.eth1_data_votes.count(body.eth1_data) * 2 >
       SLOTS_PER_ETH1_VOTING_PERIOD:
     state.eth1_data = body.eth1_data
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#is_slashable_validator
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#is_slashable_validator
 func is_slashable_validator(validator: Validator, epoch: Epoch): bool =
   # Check if ``validator`` is slashable.
   (not validator.slashed) and
     (validator.activation_epoch <= epoch) and
     (epoch < validator.withdrawable_epoch)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#proposer-slashings
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#proposer-slashings
 proc process_proposer_slashing*(
     state: var BeaconState, proposer_slashing: ProposerSlashing,
     flags: UpdateFlags, stateCache: var StateCache): bool =
@@ -205,7 +205,7 @@ proc processProposerSlashings(
 
   true
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#is_slashable_attestation_data
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#is_slashable_attestation_data
 func is_slashable_attestation_data(
     data_1: AttestationData, data_2: AttestationData): bool =
   ## Check if ``data_1`` and ``data_2`` are slashable according to Casper FFG
@@ -217,7 +217,7 @@ func is_slashable_attestation_data(
     (data_1.source.epoch < data_2.source.epoch and
      data_2.target.epoch < data_1.target.epoch)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#attester-slashings
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#attester-slashings
 proc process_attester_slashing*(
        state: var BeaconState,
        attester_slashing: AttesterSlashing,
@@ -305,7 +305,7 @@ proc processDeposits(state: var BeaconState, blck: BeaconBlock): bool =
 
   true
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#voluntary-exits
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#voluntary-exits
 proc process_voluntary_exit*(
     state: var BeaconState,
     exit: VoluntaryExit,
diff --git a/beacon_chain/spec/state_transition_epoch.nim b/beacon_chain/spec/state_transition_epoch.nim
index 9e6934610..ab5929b84 100644
--- a/beacon_chain/spec/state_transition_epoch.nim
+++ b/beacon_chain/spec/state_transition_epoch.nim
@@ -55,13 +55,13 @@ declareGauge beacon_previous_justified_root, "Current previously justified root"
 # Spec
 # --------------------------------------------------------
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_total_active_balance
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_total_active_balance
 func get_total_active_balance*(state: BeaconState): Gwei =
   return get_total_balance(
     state,
     get_active_validator_indices(state, get_current_epoch(state)))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#helper-functions-1
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#helper-functions-1
 func get_matching_source_attestations(state: BeaconState, epoch: Epoch):
     seq[PendingAttestation] =
   doAssert epoch in [get_current_epoch(state), get_previous_epoch(state)]
@@ -188,7 +188,7 @@ func get_winning_crosslink_and_attesting_indices(
   (winning_crosslink,
    get_unslashed_attesting_indices(state, winning_attestations, stateCache))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#justification-and-finalization
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#justification-and-finalization
 proc process_justification_and_finalization*(
     state: var BeaconState, stateCache: var StateCache) =
 
@@ -227,11 +227,11 @@ proc process_justification_and_finalization*(
   ## matter -- in the next epoch, they'll be 2 epochs old, when BeaconState
   ## tracks current_epoch_attestations and previous_epoch_attestations only
   ## per
-  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#attestations
+  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#attestations
   ## and `get_matching_source_attestations(...)` via
-  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#helper-functions-1
+  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#helper-functions-1
   ## and
-  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#final-updates
+  ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#final-updates
   ## after which the state.previous_epoch_attestations is replaced.
   trace "Non-attesting indices in previous epoch",
     missing_all_validators=
@@ -320,7 +320,7 @@ proc process_justification_and_finalization*(
       checkpoint = shortLog(state.finalized_checkpoint),
       cat = "finalization"
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#crosslinks
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#crosslinks
 func process_crosslinks*(state: var BeaconState, stateCache: var StateCache) =
   state.previous_crosslinks = state.current_crosslinks
 
@@ -341,7 +341,7 @@ func process_crosslinks*(state: var BeaconState, stateCache: var StateCache) =
           2'u64 * get_total_balance(state, crosslink_committee):
         state.current_crosslinks[shard] = winning_crosslink
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#rewards-and-penalties-1
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#rewards-and-penalties-1
 func get_base_reward(state: BeaconState, index: ValidatorIndex): Gwei =
   let
     total_balance = get_total_active_balance(state)
@@ -349,7 +349,7 @@ func get_base_reward(state: BeaconState, index: ValidatorIndex): Gwei =
   effective_balance * BASE_REWARD_FACTOR div
     integer_squareroot(total_balance) div BASE_REWARDS_PER_EPOCH
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#rewards-and-penalties-1
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#rewards-and-penalties-1
 func get_attestation_deltas(state: BeaconState, stateCache: var StateCache):
     tuple[a: seq[Gwei], b: seq[Gwei]] =
   let
@@ -446,7 +446,7 @@ func get_attestation_deltas(state: BeaconState, stateCache: var StateCache):
 
   (rewards, penalties)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#rewards-and-penalties-1
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#rewards-and-penalties-1
 func get_crosslink_deltas*(state: BeaconState, cache: var StateCache):
     tuple[a: seq[Gwei], b: seq[Gwei]] =
 
@@ -475,7 +475,7 @@ func get_crosslink_deltas*(state: BeaconState, cache: var StateCache):
 
   (rewards, penalties)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#rewards-and-penalties-1
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#rewards-and-penalties-1
 func process_rewards_and_penalties(
     state: var BeaconState, cache: var StateCache) =
   if get_current_epoch(state) == GENESIS_EPOCH:
@@ -489,7 +489,7 @@ func process_rewards_and_penalties(
     increase_balance(state, i.ValidatorIndex, rewards1[i] + rewards2[i])
     decrease_balance(state, i.ValidatorIndex, penalties1[i] + penalties2[i])
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#slashings
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#slashings
 func process_slashings*(state: var BeaconState) =
   let
     epoch = get_current_epoch(state)
@@ -506,7 +506,7 @@ func process_slashings*(state: var BeaconState) =
       let penalty = penalty_numerator div total_balance * increment
       decrease_balance(state, index.ValidatorIndex, penalty)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#final-updates
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#final-updates
 proc process_final_updates*(state: var BeaconState) =
   let
     current_epoch = get_current_epoch(state)
@@ -569,7 +569,7 @@ proc process_final_updates*(state: var BeaconState) =
   state.previous_epoch_attestations = state.current_epoch_attestations
   state.current_epoch_attestations = @[]
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#per-epoch-processing
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#per-epoch-processing
 proc process_epoch*(state: var BeaconState) =
   # @proc are placeholders
 
@@ -578,19 +578,19 @@ proc process_epoch*(state: var BeaconState) =
 
   var per_epoch_cache = get_empty_per_epoch_cache()
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#justification-and-finalization
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#justification-and-finalization
   process_justification_and_finalization(state, per_epoch_cache)
 
   trace "ran process_justification_and_finalization",
     current_epoch = get_current_epoch(state)
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#crosslinks
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#crosslinks
   process_crosslinks(state, per_epoch_cache)
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#rewards-and-penalties-1
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#rewards-and-penalties-1
   process_rewards_and_penalties(state, per_epoch_cache)
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#registry-updates
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#registry-updates
   # Don't rely on caching here.
   process_registry_updates(state)
 
@@ -601,10 +601,10 @@ proc process_epoch*(state: var BeaconState) =
   # @process_reveal_deadlines
   # @process_challenge_deadlines
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#slashings
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#slashings
   process_slashings(state)
 
-  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#final-updates
+  # https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#final-updates
   process_final_updates(state)
 
   # @after_process_final_updates
diff --git a/beacon_chain/spec/state_transition_helpers.nim b/beacon_chain/spec/state_transition_helpers.nim
index ea7492955..332b70d6e 100644
--- a/beacon_chain/spec/state_transition_helpers.nim
+++ b/beacon_chain/spec/state_transition_helpers.nim
@@ -22,7 +22,7 @@ func shortLog*(x: Checkpoint): string =
 # Helpers used in epoch transition and trace-level block transition
 # --------------------------------------------------------
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#helper-functions-1
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#helper-functions-1
 func get_attesting_indices*(
     state: BeaconState, attestations: openarray[PendingAttestation],
     stateCache: var StateCache): HashSet[ValidatorIndex] =
diff --git a/beacon_chain/spec/validator.nim b/beacon_chain/spec/validator.nim
index bb58c9da2..0fa476146 100644
--- a/beacon_chain/spec/validator.nim
+++ b/beacon_chain/spec/validator.nim
@@ -12,8 +12,8 @@ import
   ./crypto, ./datatypes, ./digest, ./helpers
 
 # TODO: Proceed to renaming and signature changes
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#compute_shuffled_index
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#compute_committee
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compute_shuffled_index
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compute_committee
 func get_shuffled_seq*(seed: Eth2Digest,
                        list_size: uint64,
                        ): seq[ValidatorIndex] =
@@ -79,7 +79,7 @@ func get_shuffled_seq*(seed: Eth2Digest,
 
   result = shuffled_active_validator_indices
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_previous_epoch
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_previous_epoch
 func get_previous_epoch*(state: BeaconState): Epoch =
   # Return the previous epoch (unless the current epoch is ``GENESIS_EPOCH``).
   let current_epoch = get_current_epoch(state)
@@ -88,14 +88,14 @@ func get_previous_epoch*(state: BeaconState): Epoch =
   else:
     current_epoch - 1
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_shard_delta
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_shard_delta
 func get_shard_delta*(state: BeaconState, epoch: Epoch): uint64 =
   ## Return the number of shards to increment ``state.start_shard``
   ## during ``epoch``.
   min(get_committee_count(state, epoch),
     (SHARD_COUNT - SHARD_COUNT div SLOTS_PER_EPOCH).uint64)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_start_shard
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_start_shard
 func get_start_shard*(state: BeaconState, epoch: Epoch): Shard =
   # Return the start shard of the 0th committee at ``epoch``.
 
@@ -111,7 +111,7 @@ func get_start_shard*(state: BeaconState, epoch: Epoch): Shard =
       SHARD_COUNT
   return shard
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#compute_committee
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#compute_committee
 func compute_committee(indices: seq[ValidatorIndex], seed: Eth2Digest,
     index: uint64, count: uint64, stateCache: var StateCache): seq[ValidatorIndex] =
   ## Return the committee corresponding to ``indices``, ``seed``, ``index``,
@@ -136,7 +136,7 @@ func compute_committee(indices: seq[ValidatorIndex], seed: Eth2Digest,
     start.int .. (endIdx.int-1),
     indices[stateCache.crosslink_committee_cache[key][it]])
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_crosslink_committee
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_crosslink_committee
 func get_crosslink_committee*(state: BeaconState, epoch: Epoch, shard: Shard,
     stateCache: var StateCache): seq[ValidatorIndex] =
 
@@ -175,7 +175,7 @@ func get_empty_per_epoch_cache*(): StateCache =
   result.start_shard_cache = initTable[Epoch, Shard]()
   result.committee_count_cache = initTable[Epoch, uint64]()
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#get_beacon_proposer_index
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#get_beacon_proposer_index
 func get_beacon_proposer_index*(state: BeaconState, stateCache: var StateCache):
     ValidatorIndex =
   # Return the beacon proposer index at the current slot.
diff --git a/beacon_chain/state_transition.nim b/beacon_chain/state_transition.nim
index 2638820b4..6b0159f32 100644
--- a/beacon_chain/state_transition.nim
+++ b/beacon_chain/state_transition.nim
@@ -44,7 +44,7 @@ declareGauge beacon_previous_epoch_orphaned_blocks, "Number of blocks orphaned i
 # Canonical state transition functions
 # ---------------------------------------------------------------
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
 func process_slot*(state: var BeaconState) =
   # Cache state root
   let previous_state_root = hash_tree_root(state)
@@ -81,7 +81,7 @@ func get_epoch_validator_count(state: BeaconState): int64 =
        validator.withdrawable_epoch > get_current_epoch(state):
       result += 1
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
 proc process_slots*(state: var BeaconState, slot: Slot) =
   doAssert state.slot <= slot
 
@@ -97,7 +97,7 @@ proc process_slots*(state: var BeaconState, slot: Slot) =
     if is_epoch_transition:
       beacon_current_validators.set(get_epoch_validator_count(state))
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
 proc verifyStateRoot(state: BeaconState, blck: BeaconBlock): bool =
   # This is inlined in state_transition(...) in spec.
   let state_root = hash_tree_root(state)
@@ -171,7 +171,7 @@ proc state_transition*(
 # Hashed-state transition functions
 # ---------------------------------------------------------------
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
 func process_slot(state: var HashedBeaconState) =
   # Cache state root
   let previous_slot_state_root = state.root
@@ -186,7 +186,7 @@ func process_slot(state: var HashedBeaconState) =
   state.data.block_roots[state.data.slot mod SLOTS_PER_HISTORICAL_ROOT] =
     signing_root(state.data.latest_block_header)
 
-# https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
+# https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_beacon-chain.md#beacon-chain-state-transition-function
 proc process_slots*(state: var HashedBeaconState, slot: Slot) =
   # TODO: Eth specs strongly assert that state.data.slot <= slot
   #       This prevents receiving attestation in any order
diff --git a/beacon_chain/time.nim b/beacon_chain/time.nim
index f9abea8cd..fc5cc6baa 100644
--- a/beacon_chain/time.nim
+++ b/beacon_chain/time.nim
@@ -14,7 +14,7 @@ type
     ## which blocks are valid - in particular, blocks are not valid if they
     ## come from the future as seen from the local clock.
     ##
-    ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.3/specs/core/0_fork-choice.md#fork-choice
+    ## https://github.com/ethereum/eth2.0-specs/blob/v0.8.4/specs/core/0_fork-choice.md#fork-choice
     ##
     # TODO replace time in chronos with a proper unit type, then this code can
     #      follow: