Struct pallet_babe::RandomnessFromOneEpochAgo[−][src]

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 CurrentBlockRandomness and does not require the extra finality delay of RandomnessFromTwoEpochsAgo.

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)

Get the most recently determined random seed, along with the time in the past since when it was determinable by chain observers. Read more

fn random_seed() -> (Output, BlockNumber)

Get the basic random seed. Read more

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 T where
    T: 'static + ?Sized,

pub fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more

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

pub fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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

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

Mutably borrows from an owned value. Read more

impl<T> CheckedConversion for T

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

Convert from a value of T into an equivalent instance of Option<Self>. Read more

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

Consume self to return Some equivalent value of Option<T>. Read more

impl<T> Downcast for T where
    T: Any,

pub fn into_any(self: Box<T, Global>) -> Box<dyn Any + 'static, Global>

Convert Box<dyn Trait> (where Trait: Downcast) to Box<dyn Any>. Box<dyn Any> can then be further downcast into Box<ConcreteType> where ConcreteType implements Trait. Read more

pub fn into_any_rc(self: Rc<T>) -> Rc<dyn Any + 'static>

Convert Rc<Trait> (where Trait: Downcast) to Rc<Any>. Rc<Any> can then be further downcast into Rc<ConcreteType> where ConcreteType implements Trait. Read more

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

Convert &Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &Any’s vtable from &Trait’s. Read more

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

Convert &mut Trait (where Trait: Downcast) to &Any. This is needed since Rust cannot generate &mut Any’s vtable from &mut Trait’s. Read more

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

pub fn into_any_arc(self: Arc<T>) -> Arc<dyn Any + Sync + Send + 'static>

Convert Arc<Trait> (where Trait: Downcast) to Arc<Any>. Arc<Any> can then be further downcast into Arc<ConcreteType> where ConcreteType implements Trait. Read more

impl<T> From<T> for T

pub fn from(t: T) -> T

Performs the conversion.

impl<T> Instrument for T

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

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more

fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more

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

pub fn into(self) -> U

Performs the conversion.

impl<T> IsType<T> for T

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

Cast reference.

pub fn into_ref(&self) -> &T

Cast reference.

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

Cast mutable reference.

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

Cast mutable reference.

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

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

Get a reference to the inner from the outer.

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

Get a mutable reference to the inner from the outer.

impl<T> Same<T> for T

type Output = T

Should always be Self

impl<T> SaturatedConversion for T

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

Convert from a value of T into an equivalent instance of Self. Read more

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

Consume self to return an equivalent value of T. Read more

impl<SS, SP> SupersetOf<SS> for SP where
    SS: SubsetOf<SP>,

pub fn to_subset(&self) -> Option<SS>

The inverse inclusion map: attempts to construct self from the equivalent element of its superset. Read more

pub fn is_in_subset(&self) -> bool

Checks if self is actually part of its subset T (and can be converted to it).

pub fn to_subset_unchecked(&self) -> SS

Use with care! Same as self.to_subset but without any property checks. Always succeeds.

pub fn from_subset(element: &SS) -> SP

The inclusion map: converts self to the equivalent element of its superset.

impl<T, U> TryFrom<U> for T where
    U: Into<T>,

type Error = Infallible

The type returned in the event of a conversion error.

pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>,

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

impl<S, T> UncheckedInto<T> for S where
    T: UncheckedFrom<S>,

pub fn unchecked_into(self) -> T

The counterpart to unchecked_from.

impl<T, S> UniqueSaturatedInto<T> for S where
    T: Bounded,
    S: TryInto<T>,

pub fn unique_saturated_into(self) -> T

Consume self to return an equivalent value of T.

impl<V, T> VZip<V> for T where
    V: MultiLane<T>,

pub fn vzip(self) -> V

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