pezkuwichain/pezkuwi-subxt
1
0
Fork 0
mirror of https://github.com/pezkuwichain/pezkuwi-subxt.git synced 2026-06-14 12:11:09 +00:00
Code Issues Packages Projects Releases Wiki Activity

more clear randomness API for BABE (#8180)

Browse Source 
* more clear randomness API for BABE

* babe: move randomness utilities to its own file

* node: use babe::RandomnessFromOneEpochAgo in random_seed implementation

* frame-support: annotate randomness trait with block number

* pallet-randomness-collective-flip: fix for new randomness trait

* pallet-society: fix randomness usage

* pallet-lottery: fix randomness usage

* pallet-contracts: fix randomness usage

* pallet-babe: fix randomness usage

we need to track when the current and previous epoch started so that we
know the block number by each existing on-chain was known

* node: fix random_seed

* node-template: fix random_seed

* frame-support: extend docs

* babe: add test for epoch starting block number tracking

* babe: fix epoch randomness docs

* frame: add todos for dealing with randomness api changes

Co-authored-by: André Silva <andrerfosilva@gmail.com>
This commit is contained in:
Robert Habermeier
2021-03-10 10:31:49 -06:00
committed by GitHub
parent f3d4355a20
commit e2960c383e
18 changed files with 286 additions and 78 deletions
Download Patch File Download Diff File Expand all files Collapse all files
substrate/frame/babe/src/lib.rs
+20 -28
View File
@@ -25,7 +25,7 @@ use codec::{Decode, Encode};
use frame_support::{
decl_error, decl_module, decl_storage,
dispatch::DispatchResultWithPostInfo,
traits::{FindAuthor, Get, KeyOwnerProofSystem, OneSessionHandler, Randomness as RandomnessT},
traits::{FindAuthor, Get, KeyOwnerProofSystem, OneSessionHandler},
weights::{Pays, Weight},
Parameter,
};
@@ -33,7 +33,7 @@ use frame_system::{ensure_none, ensure_root, ensure_signed};
use sp_application_crypto::Public;
use sp_runtime::{
generic::DigestItem,
traits::{Hash, IsMember, One, SaturatedConversion, Saturating, Zero},
traits::{IsMember, One, SaturatedConversion, Saturating, Zero},
ConsensusEngineId, KeyTypeId,
};
use sp_session::{GetSessionNumber, GetValidatorCount};
@@ -49,8 +49,9 @@ use sp_consensus_vrf::schnorrkel;
pub use sp_consensus_babe::{AuthorityId, PUBLIC_KEY_LENGTH, RANDOMNESS_LENGTH, VRF_OUTPUT_LENGTH};
mod equivocation;
mod default_weights;
mod equivocation;
mod randomness;
#[cfg(any(feature = "runtime-benchmarks", test))]
mod benchmarking;
@@ -60,6 +61,9 @@ mod mock;
mod tests;
pub use equivocation::{BabeEquivocationOffence, EquivocationHandler, HandleEquivocation};
pub use randomness::{
CurrentBlockRandomness, RandomnessFromOneEpochAgo, RandomnessFromTwoEpochsAgo,
};
pub trait Config: pallet_timestamp::Config {
/// The amount of time, in slots, that each epoch should last.
@@ -220,6 +224,13 @@ decl_storage! {
/// secondary plain slots are enabled (which don't contain a VRF output).
AuthorVrfRandomness get(fn author_vrf_randomness): MaybeRandomness;
/// The block numbers when the last and current epoch have started, respectively `N-1` and
/// `N`.
/// NOTE: We track this is in order to annotate the block number when a given pool of
/// entropy was fixed (i.e. it was known to chain observers). Since epochs are defined in
/// slots, which may be skipped, the block numbers may not line up with the slot numbers.
EpochStart: (T::BlockNumber, T::BlockNumber);
/// How late the current block is compared to its parent.
///
/// This entry is populated as part of block execution and is cleaned up
@@ -343,31 +354,6 @@ decl_module! {
}
}
impl<T: Config> RandomnessT<<T as frame_system::Config>::Hash> for Module<T> {
/// Some BABE blocks have VRF outputs where the block producer has exactly one bit of influence,
/// either they make the block or they do not make the block and thus someone else makes the
/// next block. Yet, this randomness is not fresh in all BABE blocks.
///
/// If that is an insufficient security guarantee then two things can be used to improve this
/// randomness:
///
/// - Name, in advance, the block number whose random value will be used; ensure your module
/// retains a buffer of previous random values for its subject and then index into these in
/// order to obviate the ability of your user to look up the parent hash and choose when to
/// transact based upon it.
/// - Require your user to first commit to an additional value by first posting its hash.
/// Require them to reveal the value to determine the final result, hashing it with the
/// output of this random function. This reduces the ability of a cabal of block producers
/// from conspiring against individuals.
fn random(subject: &[u8]) -> T::Hash {
let mut subject = subject.to_vec();
subject.reserve(VRF_OUTPUT_LENGTH);
subject.extend_from_slice(&Self::randomness()[..]);
<T as frame_system::Config>::Hashing::hash(&subject[..])
}
}
/// A BABE public key
pub type BabeKey = [u8; PUBLIC_KEY_LENGTH];
@@ -492,6 +478,12 @@ impl<T: Config> Module<T> {
// Update the next epoch authorities.
NextAuthorities::put(&next_authorities);
// Update the start blocks of the previous and new current epoch.
<EpochStart<T>>::mutate(|(previous_epoch_start_block, current_epoch_start_block)| {
*previous_epoch_start_block = sp_std::mem::take(current_epoch_start_block);
*current_epoch_start_block = <frame_system::Module<T>>::block_number();
});
// After we update the current epoch, we signal the *next* epoch change
// so that nodes can track changes.
let next_randomness = NextRandomness::get();