Struct pallet_babe::RandomnessFromOneEpochAgo

source ·

pub struct RandomnessFromOneEpochAgo<T>(_);

Expand description

Randomness usable by on-chain code that does not depend upon finality and takes action based upon on-chain commitments made during the previous epoch.

All randomness is relative to commitments to any other inputs to the computation: If Alice samples randomness near perfectly using radioactive decay, but then afterwards Eve selects an arbitrary value with which to xor Alice’s randomness, then Eve always wins whatever game they play.

All input commitments used with RandomnessFromOneEpochAgo should come from at least two epochs ago, although the previous epoch might work in special cases under additional assumption.

All users learn RandomnessFromOneEpochAgo at the end of the previous epoch, although some block producers learn it several block earlier.

Adversaries with enough block producers could bias this randomness by choosing upon what their block producers build at either the end of the previous epoch or the beginning of the current epoch, or electing to skipping some of their own block production slots towards the end of the previous epoch.

Adversaries should not possess many block production slots towards the beginning or end of every epoch, but they possess some influence over when they possess more slots.

As an example usage, we determine parachain auctions ending times in Polkadot using RandomnessFromOneEpochAgo because it reduces bias from ParentBlockRandomness and does not require the extra finality delay of RandomnessFromTwoEpochsAgo.

Struct pallet_babe::RandomnessFromOneEpochAgo

Trait Implementations§

impl<T: Config> Randomness<<T as Config>::Hash, <T as Config>::BlockNumber> for RandomnessFromOneEpochAgo<T>

fn random(subject: &[u8]) -> (T::Hash, T::BlockNumber)

fn random_seed() -> (Output, BlockNumber)

Auto Trait Implementations§

impl<T> RefUnwindSafe for RandomnessFromOneEpochAgo<T>where T: RefUnwindSafe,

impl<T> Send for RandomnessFromOneEpochAgo<T>where T: Send,

impl<T> Sync for RandomnessFromOneEpochAgo<T>where T: Sync,

impl<T> Unpin for RandomnessFromOneEpochAgo<T>where T: Unpin,

impl<T> UnwindSafe for RandomnessFromOneEpochAgo<T>where T: UnwindSafe,

Blanket Implementations§

impl<T> Any for Twhere T: 'static + ?Sized,

fn type_id(&self) -> TypeId

impl<T> Borrow<T> for Twhere T: ?Sized,

fn borrow(&self) -> &T

impl<T> BorrowMut<T> for Twhere T: ?Sized,

fn borrow_mut(&mut self) -> &mut T

impl<T> CheckedConversion for T

fn checked_from<T>(t: T) -> Option<Self>where Self: TryFrom<T>,

fn checked_into<T>(self) -> Option<T>where Self: TryInto<T>,

impl<T> Conv for T

fn conv<T>(self) -> Twhere Self: Into<T>,

impl<T> Downcast for Twhere T: Any,

fn into_any(self: Box<T, Global>) -> Box<dyn Any, Global>

fn into_any_rc(self: Rc<T>) -> Rc<dyn Any>

fn as_any(&self) -> &(dyn Any + 'static)

fn as_any_mut(&mut self) -> &mut (dyn Any + 'static)

impl<T> DowncastSync for Twhere T: Any + Send + Sync,

fn into_any_arc(self: Arc<T>) -> Arc<dyn Any + Sync + Send>

impl<T> FmtForward for T

fn fmt_binary(self) -> FmtBinary<Self>where Self: Binary,

fn fmt_display(self) -> FmtDisplay<Self>where Self: Display,

fn fmt_lower_exp(self) -> FmtLowerExp<Self>where Self: LowerExp,

fn fmt_lower_hex(self) -> FmtLowerHex<Self>where Self: LowerHex,

fn fmt_octal(self) -> FmtOctal<Self>where Self: Octal,

fn fmt_pointer(self) -> FmtPointer<Self>where Self: Pointer,

fn fmt_upper_exp(self) -> FmtUpperExp<Self>where Self: UpperExp,

fn fmt_upper_hex(self) -> FmtUpperHex<Self>where Self: UpperHex,

fn fmt_list(self) -> FmtList<Self>where &'a Self: for<'a> IntoIterator,

impl<T> From<T> for T

fn from(t: T) -> T

impl<T> Instrument for T

fn instrument(self, span: Span) -> Instrumented<Self>

fn in_current_span(self) -> Instrumented<Self>

impl<T, U> Into<U> for Twhere U: From<T>,

fn into(self) -> U

impl<T> IsType<T> for T

fn from_ref(t: &T) -> &T

fn into_ref(&self) -> &T

fn from_mut(t: &mut T) -> &mut T

fn into_mut(&mut self) -> &mut T

impl<T, Outer> IsWrappedBy<Outer> for Twhere Outer: AsRef<T> + AsMut<T> + From<T>, T: From<Outer>,

fn from_ref(outer: &Outer) -> &T

fn from_mut(outer: &mut Outer) -> &mut T

impl<T> Pipe for Twhere T: ?Sized,

fn pipe<R>(self, func: impl FnOnce(Self) -> R) -> Rwhere Self: Sized,

fn pipe_ref<'a, R>(&'a self, func: impl FnOnce(&'a Self) -> R) -> Rwhere R: 'a,

fn pipe_ref_mut<'a, R>(&'a mut self, func: impl FnOnce(&'a mut Self) -> R) -> Rwhere R: 'a,

fn pipe_borrow<'a, B, R>(&'a self, func: impl FnOnce(&'a B) -> R) -> Rwhere Self: Borrow<B>, B: 'a + ?Sized, R: 'a,

fn pipe_borrow_mut<'a, B, R>( &'a mut self, func: impl FnOnce(&'a mut B) -> R ) -> Rwhere Self: BorrowMut<B>, B: 'a + ?Sized, R: 'a,

fn pipe_as_ref<'a, U, R>(&'a self, func: impl FnOnce(&'a U) -> R) -> Rwhere Self: AsRef<U>, U: 'a + ?Sized, R: 'a,

fn pipe_as_mut<'a, U, R>(&'a mut self, func: impl FnOnce(&'a mut U) -> R) -> Rwhere Self: AsMut<U>, U: 'a + ?Sized, R: 'a,

fn pipe_deref<'a, T, R>(&'a self, func: impl FnOnce(&'a T) -> R) -> Rwhere Self: Deref<Target = T>, T: 'a + ?Sized, R: 'a,

fn pipe_deref_mut<'a, T, R>( &'a mut self, func: impl FnOnce(&'a mut T) -> R ) -> Rwhere Self: DerefMut<Target = T> + Deref, T: 'a + ?Sized, R: 'a,

impl<T> Pointable for T

const ALIGN: usize = mem::align_of::<T>()

type Init = T

unsafe fn init(init: <T as Pointable>::Init) -> usize

unsafe fn deref<'a>(ptr: usize) -> &'a T

unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

unsafe fn drop(ptr: usize)

impl<T> Same<T> for T

type Output = T

impl<T> SaturatedConversion for T

fn saturated_from<T>(t: T) -> Selfwhere Self: UniqueSaturatedFrom<T>,

fn saturated_into<T>(self) -> Twhere Self: UniqueSaturatedInto<T>,

impl<T> Tap for T

fn tap(self, func: impl FnOnce(&Self)) -> Self

fn tap_mut(self, func: impl FnOnce(&mut Self)) -> Self