* collect signature production and verificaiton in one place
Signatures are made over data and domain - here we collect all such
activities in one place.
Also:
* security: fix cast-before-range-check
* log block/attestation verification consistently
* run block verification based on `getProposer` in its own history
* clean up some unused stuff
* import
* missing raises
* random fixes
* create dump dir on startup
* don't crash on failure to write dump
* fix a few `uint64` instances being used when indexing arrays - this
should be a compile error but isn't due to compiler bugs
* fix standalone test_block_pool compilation
* add signed block processing in ncli
* reuse cache entry instead of allocating a new one
* allow for small clock disparities when validating blocks
* reorder ssz
* split into hash_trees and ssz_serialization, roughly, for hashing and
IO
* move bitseqs into ssz (from stew)
* clean up imports
* docs, imports
* sync fixes
* fix Status message finalized info
* work around sync starting before initial status exchange
* don't fail block on deposit signature check failure (fixes#989)
* print ForkDigest and Version nicely
* dump incoming blocks
* fix crash when libp2p peer connection is closed
* update chunk size to 16 to work around missing blocks when syncing
* bump libp2p
* bump libp2p
* better deposit skip message
* fix some warnings related to beacon_node splitting; reimplement finalization verification more robustly; improve attestation pool block selection logic
* re-add missing import
* whitelist allowed state transition flags and make rollback/restore naming more consistent
* restore usage of update flags passed into skipAndUpdateState(...) in addition to the potential verifyFinalization flag
* switch rest of rollback -> restore
* remove near-duplicate code paths: process_slot(), process_slots(), and state_transition() for BeaconState are now wrappers around the HashedBeaconState versions
* convert tests/test_state_transition.nim to use HashedBeaconState
* convert mocking infrastructure and spec_block/epoch_processing tests to use HashedBeaconBlock, and remove thus unused process_slot*(state: var BeaconState)
* add another check for inconsistent aggregation and committee length, since ncli_transition bypasses process_attestation(...)/check_attestation(...) and calls almost directly into process_epoch(...)
* bump validator functions to v0.11.1 spec references
* bump some spec references to v0.11.1
* poke
* initial extended validation setup
* flesh out all TODO items for attestation and beaconblock verification
* fix finalization and add chronicles debugging messages
* directly use blockPool.headState rather than pointlessly updating it and document this constraint
* fix logic relating to first-attestation checking; support validating blocks across multiple forks
* initial 0.11.1 spec commit; no test regressions and finalizes in eth2_network_simulation
* with BLS 0.10/0.11 available, stop skipping attester slashing, proposer slashing, and voluntary exist operations fixture tests
* switch param orders to group state.{fork, genesis_validators_root}; bump spec/datatypes spec version for network purposes
* mark attestation construction and broadcast and some minimal/mainnet constants as 0.11.1-compatible; remove phase 1 sharding constants from minimal which don't exist in that preset
* Initial implementation of runtime bls skipping.
Add libnfuzz skipBLSValidation handling, check that it propagates.
* Rename skipBLSValidation -> skipBlsValidation, start skipStateRootValidation
* Replace skipValidation flags with more granular flags.
Also added skipBlockParentRootValidation flag
Mainly replaced with skipBlsValidation but also StateRoot or
BlockParentRootValidation flags where appropriate.
* Adjust interop test to pass when skipping merkle validation.
* Stop skipping validation for mainchain_monitor.
* Remove comment.
* Also skipMerkleValidation for test_beacon_chain_db.
* update to 0.10.1
* SSZ Generic and nbench uses the v0.10.1 fixtures
* Tests + spec links: v0.10.0 -> v0.10.1
* Add v0.10.1 TODO in get_latest_attesting_balance (forkchoice)
* SSZ Bytes are now ByteList
* Remove nim-result submodules that was leftover/added by mistake in the branch
* nbench PoC
* Remove the yaml files from the example scenarios
* update README with current status
* Add an alternative implementation that uses defer
* Forgot to add the old proc body
* slots-processing
* allow benching state_transition failures
* Add Attestations processing (workaround confutils bug:
- https://github.com/status-im/nim-confutils/issues/10
- https://github.com/status-im/nim-confutils/issues/11
- https://github.com/status-im/nim-confutils/issues/12
* Add CLI command in the readme
* Filter report and add notes about CPU cycles
* Report averages
* Add debugecho style time/cycle print
* Report when we skip BLS and state root verification
* Update to 0.9.3
* Generalize scenario parsing
* Support all block processing scenarios
* parallel bench runner PoC
* gitBetter load issues reporting (the load issues were invalid signature and expected to fail)
* re-enable test_interop based on zcli with 0.9.1 specs and update initialize_beacon_state_from_eth1(...) to 0.9.1
* switch many procs to funcs
* fix import os.nim instead; ospaths is deprecated [Deprecated] warnings
* transition deposit operations fixture to 0.9.0
* mark slash_validator(...) as 0.9.0
* switch remaining non-ref objects to ref objects to maybe avoid crashes in CI
* remove unused helpers/debug_state imports
* rename compute_epoch_of_slot(...) to compute_epoch_at_slot(...)
* remove some unnecessary imports; remove some crosslink-related code and tests; complete renaming of compute_epoch_of_slot(...) to compute_epoch_at_slot(...)
* rm more transfer-related code and tests; rm more unnecessary strutils imports
* rm remaining unused imports
* remove useless get_empty_per_epoch_cache(...)/compute_start_slot_of_epoch(...) calls
* rename compute_start_slot_of_epoch(...) to compute_start_slot_at_epoch(...)
* rename ACTIVATION_EXIT_DELAY to MAX_SEED_LOOKAHEAD
* update domain types to 0.9.0
* mark AttesterSlashing, IndexedAttestation, AttestationDataAndCustodyBit, DepositData, BeaconBlockHeader, Fork, integer_squareroot(...), and process_voluntary_exit(...) as 0.9.0
* mark increase_balance(...), decrease_balance(...), get_block_root(...), CheckPoint, Deposit, PendingAttestation, HistoricalBatch, is_active_validator(...), and is_slashable_attestation_data(...) as 0.9.0
* mark compute_activation_exit_epoch(...), bls_verify(...), Validator, get_active_validator_indices(...), get_current_epoch(...), get_total_active_balance(...), and get_previous_epoch(...) as 0.9.0
* mark get_block_root_at_slot(...), ProposerSlashing, get_domain(...), VoluntaryExit, mainnet preset Gwei values, minimal preset max operations, process_block_header(...), and is_slashable_validator(...) as 0.9.0
* mark makeWithdrawalCredentials(...), get_validator_churn_limit(...), get_total_balance(...), is_valid_indexed_attestation(...), bls_aggregate_pubkeys(...), initial genesis value/constants, Attestation, get_randao_mix(...), mainnet preset max operations per block constants, minimal preset Gwei values and time parameters, process_eth1_data(...), get_shuffled_seq(...), compute_committee(...), and process_slots(...) as 0.9.0; partially update get_indexed_attestation(...) to 0.9.0 by removing crosslink refs and associated tests
* mark initiate_validator_exit(...), process_registry_updates(...), BeaconBlock, Eth1Data, compute_domain(...), process_randao(...), process_attester_slashing(...), get_base_reward(...), and process_slot(...) as 0.9.0
* Add attestation unit test
* process_attestation doesn't throw exceptions
* Allow SSZ deserialization of both real and invalid signatures
* Add new process_attestation checks - pass all process_attestation tests
* Add sanity check for #361
* Fix SSZ testing after fromBytes/fromSSZBytes changes
* Add sanity check for slot processing (also impacted by https://github.com/status-im/nim-beacon-chain/issues/373)
* use reportDiff also for all state tests vs EF
* initial sanity checks for blocks - workaround zero signature in block headers: https://github.com/status-im/nim-beacon-chain/issues/374
* Remove generic object variant compare commented code
* Add the one block state transition sanity checks
* generalize blocks test to multiple blocks
* simplify slots test runner
* Add official epoch transitions, sanity blocks, sanity slots to the test suite
* Fix index out-of-bounds in initiate_validator_exit - enable proposer slashings unittest
* Update BLS fixtures to 0.8.3
* Bump fixtures with shuffling with minimal preset
* Update shuffling tests
* parseTest generic over file format (Json or SSZ)
* Initial crosslink parsing commit for debugging Nim crash
* Workaround https://github.com/status-im/nim-beacon-chain/issues/369
* Crosslink test works for minimal - https://github.com/status-im/nim-beacon-chain/issues/369 is back on mainnet
* Use ref objects to workaround https://github.com/status-im/nim-beacon-chain/issues/369
* Generalize state transition epoch test to all epoch tests
* Fix slashing (potential uint64 overflow in previous spec)
* Add a state debugging macro to deeply inspect the wrong fields
* make reportDiff visible
* Improve the debug state macro for containers
* add interop launcher scripts
* stick validator_keygen into beacon_node
* fix lmd ghost slot number on missing block
* use mocked eth1data when producing blocks
* use bls public key method for withdrawal credentials
* fix deposit domain
* prefer lowercase for a bunch of toHex
* build simulation binary in data folder to avoid data types confusion
* Introduce new mocking proc to replace:
- makeFakeValidatorPrivKey
- hackPrivKey
- getNextBeaconProposerIndex
- addBlock
- makeBlock
* Add comments on datastructure unsynced with the spec
* Add merkle tree constructor and initial mocking for deposits (missing merkle proofs)
* [Mock] Implement sparse merkle tree and merkle proof builder
* [Mocking] Genesis deposits
* Add compact_committees_roots init + mock genesis state
* [Tests] Add first deposit test using the new mocking procedures
* [Tests -deposits] add at and over 32 ETH deposit tests
* [Tests - deposits] Add test for validator top-up
* [Tests -deposits] Mention the TODO to test for invalid conditions
* [Tests] Add stub to test "is_valid_genesis_state"
* [Merkle proofs] Implement round-trip checks
* Deactivate roundtrips test
* SSZ - use EF convention for hash_tree_root / hashTreeRoot
* [Tests - Attestation] Attestation mocking + initial test
* Add mocking + 3 new tests for valid attestations + mention future invalid attestation tests
* Add crosslinks test (1 failing to attestations in block being duplicated in state transition)
* Single attestation crosslink test - workaround https://github.com/status-im/nim-beacon-chain/issues/361
* Add test for failed crosslink penalty
* Rebase fixes + add refactored tests to test suite
* justif-finalization helpers first batch
* Add 234 finalization tests
* Fix justif test, Rule I 234 finalization does not happen with sufficient support.
(Also unittest check template does not fail properly in some cases)
* Add tests for all finalization rules
* Properly delete nim-byteutils following c91727e7e5 (diff-7c3613dba5171cb6027c67835dd3b9d4)
* use digest helper for deposit root
* relax attestation validation when attestation is incoming but make it
more strict when adding to block
* share attestation validation logic between attestation pool and state
transition
* remove a bunch of redundant logging
* fix potential underflow in attestation delay checking
* fix committee used for attestation shard selection when attesting
* fix attestation data construction
* working justification, 1 node, 64 validators
* closer to tn1 params: 256 validators
* more debugging output; switch to minimum test case
* working justification and finalization in local network simulation
* fix currently incorrect state transition/attestation test assumption
* rename get_genesis_beacon_state(...) to initialize_beacon_state_from_eth1(...); remove unused vestiges get_temporary_block_header(...) and get_empty_block(...); partly align initialize_beacon_state_from_eth1(...) with 0.8.0 version; implement CompactCommittee object type; update process_final_updates(...) to 0.8.0
* mark get_shard_delta(...) as 0.8.0
* mark get_total_active_balance(...) and epoch transition helper functions as 0.8.0
* move FORK_CHOICE_BALANCE_INCREMENT, not in spec anymore, to sole user in fork_choice
* replace BeaconState.finalized_{epoch,root} with BeaconState.finalized_checkpoint; rename get_delayed_activation_exit_epoch(...) to compute_activation_exit_epoch(...) and mark as 0.8.0; update get_churn_limit(...)/get_validator_churn_limit(...) to 0.8.0; update process_registry_updates(...) to 0.8.0
* update process_crosslinks(...) to 0.8.0; mark compute_start_slot_of_epoch(...) and get_committee_count(...) as 0.8.0
* mark Fork, is_slashable_validator(...), and get_beacon_proposer_index(...) as 0.8.0
* rename LATEST_SLASHED_EXIT_LENGTH to EPOCHS_PER_SLASHINGS_VECTOR; update process_slashings(...) to 0.8.0; remove pointless type conversion warning in get_previous_epoch(...)
* convert remaining references to finalized_epoch to finalized_checkpoint.epoch
* update slash_validator(...) to 0.8.0; mark inital value, Gwei, and time constants as 0.8.0; mark hash(...) and processBlockHeader(...) as 0.8.0
* rename WHISTLEBLOWING_REWARD_QUOTIENT to WHISTLEBLOWER_REWARD_QUOTIENT; rename LATEST_ACTIVE_INDEX_ROOTS_LENGTH to EPOCHS_PER_HISTORICAL_VECTOR (randao will also get merged into this); remove get_active_index_root(...); mark time parameter, signature domain types, and max operations per block constants as 0.8.0; update rewards and penalties constants to 0.8.0
* update is_valid_indexed_attestation(...) to 0.8.0; mark process_slot(...) as 0.8.0
* replace BeaconState.{current,previous}_justified_{epoch,root} with BeaconState.{current,previous}_justified_checkpoint
* rename slot_to_epoch(...) to compute_epoch_of_slot(...)
* rename aggregation_bitfield/custody_bitfield fields to aggregation_bits/custody_bits; rename convert_to_indexed(...) to get_indexed_attestation(...); mark BeaconBlockHeader as 0.8.0; update minimal preset MIN_ATTESTATION_INCLUSION_DELAY/time parameters in general to 0.8
* fix beacon node compilation; it used slightly different capitalizations of slot_to_epoch/slotToEpoch
* mark integer_squareroot(...), Deposit, VoluntaryExit, and Transfer as 0.8.0; rename get_epoch_start_slot(...) to compute_start_slot_of_epoch(...)
* add new Domain alias for uint64; rename bls_domain(...) to compute_domain(...), MAX_INDICES_PER_ATTESTATION to MAX_VALIDATORS_PER_COMMITTEE, and SignatureDomain to DomainType; update get_domain(...) to 0.8.0
* update/mark initiate_validator_exit(...) and Crosslink as 0.8.0; rename BeaconState.latest_block_roots -> BeaconState.block_roots; mark HistoricalBatch as 0.8.0
* migrate attestation pool tests from get_crosslink_committees_at_slot(...) to get_crosslink_committee(...)
* rm obsolete, unused get_crosslink_committees_at_slot_cached(...) and migrate tests/test_state_transition from get_crosslink_committees_at_slot(...) to get_crosslink_committee(...)
* migrate tests/testutil from get_crosslink_committees_at_slot(...) to get_crosslink_committee(...)
* use more pervasive caching infrastructure, initially of compute_committee; remove buggy (and per-index) shuffling to fix research/state_sim, which was noticing validators on multiple shard committees; rm now-unused specific get_attesting_balance_cached
* add some get_active_validator_index caching
* rm obsolete/unused get_attesting_indices_cached
* rm get_crosslink_committees_at_slot(...)
* some more 0.7 changes -- some of which can't be completed pending some data structure updates -- and shard handling changes to offset with epoch start shards
* update Deposit and BeaconBlockHeader to 0.7.0
* update get_total_balance(...) and get_base_reward(...) to 0.7.0
* rename initial value constant BLS_WITHDRAWAL_PREFIX_BYTE to BLS_WITHDRAWAL_PREFIX
* mark minimal presets as entirely migrated to 0.7.0; update process_rewards_and_penalties(...) to 0.7.0
* specify that targeting 0.7.0; adopt 0.7.0 refactoring of bls_domain/get_domain to update get_domain(...) to 0.7.0; mark that mainnet constant presets and block header processing are 0.7.0-consistent; update process_justification_and_finalization to 0.7.0 to fix potential underflow errors
* address mratsim's comment to copy whole spec comment
* 0.7.0 updates which don't change semantics; mostly comment changes
* mark get_attesting_indices, bls_verify, ProposerSlashing, BeaconBlockBody, deposit contract constants, state list length constants, compute_committee, get_crosslink_committee, is_slashable_attestation_data, processAttesterSlashings as 0.7.0; rename BASE_REWARD_QUOTIENT to BASE_REWARD_FACTOR
* complete marking unchanged-in-0.7.0 datatypes as such; a few more have trivial field renamings, etc
* update IndexedAttestation, verify_slashable_attestation/verify_indexed_attestation, and attester slashing processing to 0.6.3
* rm debug scaffolding
* rename Attestation.aggregate_signature -> Attestation.signature; convert various references to AttestationData.slot to get_attestation_slot; implement convert_to_indexed; update checkAttestation and processAttestations to 0.6.3; remove spurious assertion in beacon node related to invalid attestations
* replace 0.5 get_winning_root_and_participants with 0.6 get_winning_crosslink_and_attesting_indices; update process_crosslinks to 0.6.3
* mark both remaining 0.6.0 spec implementations as 0.6.3
* clear out all remaining spec version 0.6.1 refs
* GENESIS_SLOT and GENESIS_EPOCH are 0
* rm 0.5 get_attestation_participants in favor of 0.6 get_attesting_indices
* address mratsim's comment
* time can be equal to genesis
* fix invalid block assertions; those were essentially spurious
* allow toBeaconTime to handle time before genesis (in accordance with now(...) which states time can exist before GENESIS)
* update process_justification_and_finalization to 0.6.2; mark AttesterSlashing as 0.6.2
* replace get_effective_balance(...) with state.validator_registry[idx].effective_balance; rm get_effective_balance, process_ejections, should_update_validator_registry, update_validator_registry, and update_registry_and_shuffling_data; update get_total_balance to 0.6.2; implement process_registry_updates
* rm exit_validator; implement is_slashable_attestation_data; partly update processAttesterSlashings
* mark HistoricalBatch and Eth1Data as 0.6.2; implement get_shard_delta(...); replace 0.5 finish_epoch_update with 0.6 process_final_updates
* mark increase_balance, decrease_balance, get_delayed_activation_exit_epoch, bls_aggregate_pubkeys, bls_verify_multiple, Attestation, Transfer, slot_to_epoch, Crosslink, get_current_epoch, int_to_bytes*, various constants, processEth1Data, processTransfers, and verifyStateRoot as 0.6.2; rm is_double_vote and is_surround_vote
* mark get_bitfield_bit, verify_bitfield, ProposerSlashing, DepositData, VoluntaryExit, PendingAttestation, Fork, integer_squareroot, get_epoch_start_slot, is_active_validator, generate_seed, some constants to 0.6.2; rename MIN_PENALTY_QUOTIENT to MIN_SLASHING_PENALTY_QUOTIENT
* rm get_previous_total_balance, get_current_epoch_boundary_attestations, get_previous_epoch_boundary_attestations, and get_previous_epoch_matching_head_attestations
* update BeaconState to 0.6.2; simplify legacy get_crosslink_committees_at_slot infrastructure a bit by noting that registry_change is always false; reimplment 0.5 get_crosslink_committees_at_slot in terms of 0.6 get_crosslink_committee
* mark process_deposit(...), get_block_root_at_slot(...), get_block_root(...), Deposit, BeaconBlockHeader, BeaconBlockBody, hash(...), get_active_index_root(...), various constants, get_shard_delta(...), get_epoch_start_shard(...), get_crosslink_committee(...), processRandao(...), processVoluntaryExits(...), cacheState(...) as 0.6.2
* rm removed-since-0.5 split(...), is_power_of_2(...), get_shuffling(...); rm 0.5 versions of get_active_validator_indices and get_epoch_committee_count; add a few tests for integer_squareroot
* mark bytes_to_int(...) and advanceState(...) as 0.6.2
* rm 0.5 get_attesting_indices; update get_attesting_balance to 0.6.2
* another tiny commit to poke AppVeyor to maybe not timeout at connecting to GitHub partway through CI: mark get_churn_limit(...), initiate_validator_exit(...), and Validator as 0.6.2
* mark get_attestation_slot(...), AttestationDataAndCustodyBit, and BeaconBlock as 0.6.2
* implement get_churn_limit from 0.6.1; update initiate_validator_exit and get_previous_epoch to 0.6.1; remove obsoleted/non-spec reduce_balance, replaced by decrease_balance; mark BeaconBlock as 0.6.1
* rename get_block_root to get_block_root_at_slot and introduce epoch-oriented get_block_root; implement get_attestation_slot, get_matching_source_attestations, get_matching_target_attestations, get_matching_head_attestations, 0.6.1 get_attesting_indices, get_unslashed_attesting_indices, get_attestation_deltas, process_rewards_and_penalties; rm get_inactivity_penalty
* update Validator and processVoluntaryExits to 0.6.1; rm obsolete inclusion_slots/inclusion_distances
* rm removed activate_validator; mark DepositData, misc values, Gwei values, Randao processing, state caching as 0.6.1; update GENESIS_SLOT to 64, since it doesn't quite yet work at 0
* mark BeaconBlockHeader as 0.6.1; update BeaconBlockBody to 0.6.1; rename WHISTLEBLOWER_REWARD_QUOTIENT to WHISTLEBLOWING_REWARD_QUOTIENT; update slash_validator to 0.6.1
* implement 0.6.2 is_slashable_validator; update processProposerSlashings to 0.6.2; mark state caching as 0.6.2
* mark get_total_active_balance and process_slashings as 0.6.2; update get_base_reward to 0.6.2
* rm prepare_validator_for_withdrawal, process_exit_queue; mark mainnet misc constants as 0.6.2; update process block header to 0.6.2
* address mratsim's code review comment
* initial new get_beacon_proposer_index and dependencies (get_shuffled_index, get_shard_delta, get_epoch_start_shard, get_crosslink_committee)
* more 0.6.1 updates
* clean up debugEchos and fix validator keygen to create correct indices
* signed_root -> signing_root
* implement new process_deposit; update timing parameters to 0.6.1; update Deposit to 0.6.1 and remove DepositInput
* update get_active_validator_indices and get_epoch_committee_count to 0.6.1; rm get_current_epoch_committee_count, get_previous_epoch_committee_count, and get_next_epoch_committee_count; bump state_sim default validator count a bit more
* re-introduce 0.5.1-ish get_active_validator_indices, get_epoch_committee_count as scaffolding for still-0.5.1ish shuffling
* begin 0.6.0: new get_domain/increase_balance/reduce_balance, BeaconState.validator_balances -> BeaconState.balances, some renamed constants, transaction processing changes, SlashableAttestation field name changes, 0.6.0 get_beacon_proposer_index always uses given state's slot, update tests subrepo
* mark get_bitfield_bit/bls_verify_multiple/stat-list-lengths/is_active_validator/is_surround_vote/slot_to_epoch/int_to_bytes/etc as unchanged in 0.6.0; rm Eth1DataVote/maybe_reset_eth1_period and thus adjust expected tree hash test results
* mark verify_bitfield/bls_verify/deposit-contract/VoluntaryExit/PendingAttestation/Historicalbatch/Fork as 0.6.0; update DOMAIN_BEACON_BLOCK to DOMAIN_BEACON_PROPOSER
* update Crosslink to 0.6.0 (also requires tree hashing test result change, so isolate in individual commit)
* mark verify_merkle_branch/get_delayed_activation_exit_epoch/ProposerSlashing/Attestation/AttestationDataAndCustodyBit/hash/integer_squareroot/get_epoch_start_slot/is_double_vote/get_randao_mix/generate_seed as 0.6.0; update reward and penalty quotients; SlashableAttestation -> IndexedAttestation; rm get_fork_version; ATTESTATION_INCLUSION_REWARD_QUOTIENT -> PROPOSER_REWARD_QUOTIENT
* fix node.state being used unsafely across async callbacks (fixes#230)
* node.state -> node.stateCache
* fix attestation validation not to use asserts
* re-enable attestation pool tests
* prepare for resizing validator registry
* rm now-superceded shuffling cache (shuffling is only called from get_crosslinks), which was badly architected due to trying to exist in state; rm one more vestige of previous light-client regime (one more to go, from datatypes)
* fix wrong shuffling list size (active validator size, not validator size) to make consistent with 0.5.1 (will be inconsistent with testnet0); fix typo and change defaults in state_sim
* doAssert a couple of constant relationships necessary to avoid underflow; rm non-spec, unused helper function get_new_recent_block_roots
* refactor separate crosslink_committee_cache and winning_root_participants_cache(s) into StateData object; remove last vestige of previous shuffling cache
* separate out caching parts of StateData to new StateCache object
* ssz: avoid memory allocations
* a bit fishy with the 32-item stack.. this should be a smallvector
* digest: avoid another burnmem
* avoid a few allocations by using iterator
Mamy Ratsimbazafy
Dustin Brody
Jacek Sieka
Zahary Karadjov
Mamy Ratsimbazafy
Yuriy Glukhov
Yuriy Glukhov
Jacek Sieka