More ergonomic digest items

primitives/consensus/sassafras/src/digests.rs

@@ -28,9 +28,11 @@ use scale_info::TypeInfo;
 use sp_runtime::{DigestItem, RuntimeDebug};
 use sp_std::vec::Vec;
 
-/// Sassafras slot assignment pre-digest.
+/// Epoch slot claim digest entry.
+///
+/// This is mandatory for each block.
 #[derive(Clone, RuntimeDebug, Encode, Decode, MaxEncodedLen, TypeInfo)]
-pub struct PreDigest {
+pub struct SlotClaim {
 	/// Authority index that claimed the slot.
 	pub authority_idx: AuthorityIndex,
 	/// Corresponding slot number.
@@ -43,18 +45,22 @@ pub struct PreDigest {
 
 /// Information about the next epoch.
 ///
-/// This is broadcast in the first block of each epoch.
+/// This is mandatory in the first block of each epoch.
 #[derive(Clone, PartialEq, Eq, Encode, Decode, RuntimeDebug)]
 pub struct NextEpochDescriptor {
 	/// Authorities list.
 	pub authorities: Vec<AuthorityId>,
 	/// Epoch randomness.
 	pub randomness: Randomness,
-	/// Configurable parameters. If not present previous epoch parameters are used.
+	/// Epoch configurable parameters.
+	///
+	/// If not present previous epoch parameters are used.
 	pub config: Option<EpochConfiguration>,
 }
 
-/// Consensus log item.
+/// Runtime digest entries.
+///
+/// Entries which may be generated by on-chain code.
 #[derive(Decode, Encode, Clone, PartialEq, Eq)]
 pub enum ConsensusLog {
 	/// Provides information about the next epoch parameters.
@@ -65,35 +71,28 @@ pub enum ConsensusLog {
 	OnDisabled(AuthorityIndex),
 }
 
-/// A digest item which is usable by Sassafras.
-pub trait CompatibleDigestItem {
-	/// Construct a digest item which contains a `PreDigest`.
-	fn sassafras_pre_digest(seal: PreDigest) -> Self;
-
-	/// If this item is a `PreDigest`, return it.
-	fn as_sassafras_pre_digest(&self) -> Option<PreDigest>;
-
-	/// Construct a digest item which contains an `AuthoritySignature`.
-	fn sassafras_seal(signature: AuthoritySignature) -> Self;
-
-	/// If this item is an `AuthoritySignature`, return it.
-	fn as_sassafras_seal(&self) -> Option<AuthoritySignature>;
+impl TryFrom<&DigestItem> for SlotClaim {
+	type Error = ();
+	fn try_from(item: &DigestItem) -> Result<Self, Self::Error> {
+		item.pre_runtime_try_to(&SASSAFRAS_ENGINE_ID).ok_or(())
+	}
 }
 
-impl CompatibleDigestItem for DigestItem {
-	fn sassafras_pre_digest(digest: PreDigest) -> Self {
-		DigestItem::PreRuntime(SASSAFRAS_ENGINE_ID, digest.encode())
+impl From<&SlotClaim> for DigestItem {
+	fn from(claim: &SlotClaim) -> Self {
+		DigestItem::PreRuntime(SASSAFRAS_ENGINE_ID, claim.encode())
 	}
+}
 
-	fn as_sassafras_pre_digest(&self) -> Option<PreDigest> {
-		self.pre_runtime_try_to(&SASSAFRAS_ENGINE_ID)
+impl TryFrom<&DigestItem> for AuthoritySignature {
+	type Error = ();
+	fn try_from(item: &DigestItem) -> Result<Self, Self::Error> {
+		item.seal_try_to(&SASSAFRAS_ENGINE_ID).ok_or(())
 	}
+}
 
-	fn sassafras_seal(signature: AuthoritySignature) -> Self {
+impl From<&AuthoritySignature> for DigestItem {
+	fn from(signature: &AuthoritySignature) -> Self {
 		DigestItem::Seal(SASSAFRAS_ENGINE_ID, signature.encode())
 	}
-
-	fn as_sassafras_seal(&self) -> Option<AuthoritySignature> {
-		self.seal_try_to(&SASSAFRAS_ENGINE_ID)
-	}
 }

primitives/consensus/sassafras/src/vrf.rs

@@ -17,7 +17,7 @@
 
 //! Utilities related to VRF input, output and signatures.
 
-use crate::{Randomness, TicketBody, TicketId, SASSAFRAS_ENGINE_ID};
+use crate::{Randomness, TicketBody, TicketId};
 use scale_codec::Encode;
 use sp_consensus_slots::Slot;
 use sp_std::vec::Vec;
@@ -52,7 +52,11 @@ pub fn slot_claim_input(randomness: &Randomness, slot: Slot, epoch: u64) -> VrfI
 /// Signing-data to claim slot ownership during block production.
 pub fn slot_claim_sign_data(randomness: &Randomness, slot: Slot, epoch: u64) -> VrfSignData {
 	let vrf_input = slot_claim_input(randomness, slot, epoch);
-	VrfSignData::new_unchecked(&SASSAFRAS_ENGINE_ID, Some("slot-claim-transcript"), Some(vrf_input))
+	VrfSignData::new_unchecked(
+		b"sassafras-slot-claim-transcript-v1.0",
+		Option::<&[u8]>::None,
+		Some(vrf_input),
+	)
 }
 
 /// VRF input to generate the ticket id.
@@ -74,8 +78,8 @@ pub fn revealed_key_input(randomness: &Randomness, attempt: u32, epoch: u64) ->
 /// Data to be signed via ring-vrf.
 pub fn ticket_body_sign_data(ticket_body: &TicketBody, ticket_id_input: VrfInput) -> VrfSignData {
 	VrfSignData::new_unchecked(
-		&SASSAFRAS_ENGINE_ID,
-		&[b"ticket-body-transcript", ticket_body.encode().as_slice()],
+		b"sassafras-ticket-body-transcript-v1.0",
+		Some(ticket_body.encode().as_slice()),
 		Some(ticket_id_input),
 	)
 }