diff --git a/substrate/core/basic-authorship/src/basic_authorship.rs b/substrate/core/basic-authorship/src/basic_authorship.rs
index 5f8d189878..0464d96dc4 100644
--- a/substrate/core/basic-authorship/src/basic_authorship.rs
+++ b/substrate/core/basic-authorship/src/basic_authorship.rs
@@ -26,8 +26,8 @@ use client::{self, error, Client as SubstrateClient, CallExecutor};
 use client::{block_builder::api::BlockBuilder as BlockBuilderApi, runtime_api::Core};
 use codec::{Decode, Encode};
 use consensus_common::{self, evaluation};
-use primitives::{H256, AuthorityId, ed25519, Blake2Hasher};
-use runtime_primitives::traits::{Block as BlockT, Hash as HashT, Header as HeaderT, ProvideRuntimeApi};
+use primitives::{H256, Ed25519AuthorityId, ed25519, Blake2Hasher};
+use runtime_primitives::traits::{Block as BlockT, Hash as HashT, Header as HeaderT, ProvideRuntimeApi, AuthorityIdFor};
 use runtime_primitives::generic::BlockId;
 use runtime_primitives::BasicInherentData;
 use transaction_pool::txpool::{self, Pool as TransactionPool};
@@ -125,8 +125,7 @@ impl<C, A, ConsensusData> consensus_common::Environment<<C as AuthoringApi>::Blo
 	fn init(
 		&self,
 		parent_header: &<<C as AuthoringApi>::Block as BlockT>::Header,
-		_: &[AuthorityId],
-		_: Arc<ed25519::Pair>,
+		_: &[AuthorityIdFor<<C as AuthoringApi>::Block>],
 	) -> Result<Self::Proposer, error::Error> {
 		let parent_hash = parent_header.hash();
 
diff --git a/substrate/core/client/db/src/cache/mod.rs b/substrate/core/client/db/src/cache/mod.rs
index db2a1762db..11fbd93392 100644
--- a/substrate/core/client/db/src/cache/mod.rs
+++ b/substrate/core/client/db/src/cache/mod.rs
@@ -24,9 +24,8 @@ use kvdb::{KeyValueDB, DBTransaction};
 use client::blockchain::Cache as BlockchainCache;
 use client::error::Result as ClientResult;
 use codec::{Encode, Decode};
-use primitives::AuthorityId;
 use runtime_primitives::generic::BlockId;
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, As};
+use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, As, AuthorityIdFor};
 use utils::{self, COLUMN_META};
 
 use self::list_cache::ListCache;
@@ -65,7 +64,7 @@ impl<T> CacheItemT for T where T: Clone + Decode + Encode + PartialEq {}
 
 /// Database-backed blockchain data cache.
 pub struct DbCache<Block: BlockT> {
-	authorities_at: ListCache<Block, Vec<AuthorityId>, self::list_storage::DbStorage>,
+	authorities_at: ListCache<Block, Vec<AuthorityIdFor<Block>>, self::list_storage::DbStorage>,
 }
 
 impl<Block: BlockT> DbCache<Block> {
@@ -112,14 +111,14 @@ impl<Block: BlockT> DbCache<Block> {
 
 /// Cache operations that are to be committed after database transaction is committed.
 pub struct DbCacheTransactionOps<Block: BlockT> {
-	authorities_at_op: Option<self::list_cache::CommitOperation<Block, Vec<AuthorityId>>>,
+	authorities_at_op: Option<self::list_cache::CommitOperation<Block, Vec<AuthorityIdFor<Block>>>>,
 }
 
 /// Database-backed blockchain data cache transaction valid for single block import.
 pub struct DbCacheTransaction<'a, Block: BlockT> {
 	cache: &'a mut DbCache<Block>,
 	tx: &'a mut DBTransaction,
-	authorities_at_op: Option<self::list_cache::CommitOperation<Block, Vec<AuthorityId>>>,
+	authorities_at_op: Option<self::list_cache::CommitOperation<Block, Vec<AuthorityIdFor<Block>>>>,
 }
 
 impl<'a, Block: BlockT> DbCacheTransaction<'a, Block> {
@@ -135,7 +134,7 @@ impl<'a, Block: BlockT> DbCacheTransaction<'a, Block> {
 		mut self,
 		parent: ComplexBlockId<Block>,
 		block: ComplexBlockId<Block>,
-		authorities_at: Option<Vec<AuthorityId>>,
+		authorities_at: Option<Vec<AuthorityIdFor<Block>>>,
 		is_final: bool,
 	) -> ClientResult<Self> {
 		assert!(self.authorities_at_op.is_none());
@@ -179,7 +178,7 @@ impl<'a, Block: BlockT> DbCacheTransaction<'a, Block> {
 pub struct DbCacheSync<Block: BlockT>(pub RwLock<DbCache<Block>>);
 
 impl<Block: BlockT> BlockchainCache<Block> for DbCacheSync<Block> {
-	fn authorities_at(&self, at: BlockId<Block>) -> Option<Vec<AuthorityId>> {
+	fn authorities_at(&self, at: BlockId<Block>) -> Option<Vec<AuthorityIdFor<Block>>> {
 		let cache = self.0.read();
 		let storage = cache.authorities_at.storage();
 		let db = storage.db();
diff --git a/substrate/core/client/db/src/lib.rs b/substrate/core/client/db/src/lib.rs
index 9df93e45b5..371f0a4013 100644
--- a/substrate/core/client/db/src/lib.rs
+++ b/substrate/core/client/db/src/lib.rs
@@ -64,10 +64,10 @@ use hash_db::Hasher;
 use kvdb::{KeyValueDB, DBTransaction};
 use trie::MemoryDB;
 use parking_lot::RwLock;
-use primitives::{H256, AuthorityId, Blake2Hasher, ChangesTrieConfiguration, convert_hash};
+use primitives::{H256, Blake2Hasher, ChangesTrieConfiguration, convert_hash};
 use primitives::storage::well_known_keys;
 use runtime_primitives::{generic::BlockId, Justification, StorageMap, ChildrenStorageMap};
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, As, NumberFor, Zero, Digest, DigestItem};
+use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, As, NumberFor, Zero, Digest, DigestItem, AuthorityIdFor};
 use runtime_primitives::BuildStorage;
 use state_machine::backend::Backend as StateBackend;
 use executor::RuntimeInfo;
@@ -315,7 +315,7 @@ where Block: BlockT<Hash=H256>,
 		Ok(())
 	}
 
-	fn update_authorities(&mut self, _authorities: Vec<AuthorityId>) {
+	fn update_authorities(&mut self, _authorities: Vec<AuthorityIdFor<Block>>) {
 		// currently authorities are not cached on full nodes
 	}
 
diff --git a/substrate/core/client/db/src/light.rs b/substrate/core/client/db/src/light.rs
index 729519020c..cbed1348a9 100644
--- a/substrate/core/client/db/src/light.rs
+++ b/substrate/core/client/db/src/light.rs
@@ -28,10 +28,10 @@ use client::{cht, LeafSet};
 use client::error::{ErrorKind as ClientErrorKind, Result as ClientResult};
 use client::light::blockchain::Storage as LightBlockchainStorage;
 use codec::{Decode, Encode};
-use primitives::{AuthorityId, Blake2Hasher};
+use primitives::Blake2Hasher;
 use runtime_primitives::generic::BlockId;
 use runtime_primitives::traits::{Block as BlockT, Header as HeaderT,
-	Zero, One, As, NumberFor, Digest, DigestItem};
+	Zero, One, As, NumberFor, Digest, DigestItem, AuthorityIdFor};
 use cache::{DbCacheSync, DbCache, ComplexBlockId};
 use utils::{meta_keys, Meta, db_err, open_database,
 	read_db, block_id_to_lookup_key, read_meta};
@@ -306,7 +306,7 @@ impl<Block> LightBlockchainStorage<Block> for LightStorage<Block>
 	fn import_header(
 		&self,
 		header: Block::Header,
-		authorities: Option<Vec<AuthorityId>>,
+		authorities: Option<Vec<AuthorityIdFor<Block>>>,
 		leaf_state: NewBlockState,
 		aux_ops: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 	) -> ClientResult<()> {
@@ -510,7 +510,7 @@ pub(crate) mod tests {
 
 	pub fn insert_block<F: Fn() -> Header>(
 		db: &LightStorage<Block>,
-		authorities: Option<Vec<AuthorityId>>,
+		authorities: Option<Vec<AuthorityIdFor<Block>>>,
 		header: F,
 	) -> Hash {
 		let header = header();
@@ -521,7 +521,7 @@ pub(crate) mod tests {
 
 	fn insert_final_block<F: Fn() -> Header>(
 		db: &LightStorage<Block>,
-		authorities: Option<Vec<AuthorityId>>,
+		authorities: Option<Vec<AuthorityIdFor<Block>>>,
 		header: F,
 	) -> Hash {
 		let header = header();
@@ -532,7 +532,7 @@ pub(crate) mod tests {
 
 	fn insert_non_best_block<F: Fn() -> Header>(
 		db: &LightStorage<Block>,
-		authorities: Option<Vec<AuthorityId>>,
+		authorities: Option<Vec<AuthorityIdFor<Block>>>,
 		header: F,
 	) -> Hash {
 		let header = header();
@@ -762,7 +762,7 @@ pub(crate) mod tests {
 	fn authorites_are_cached() {
 		let db = LightStorage::new_test();
 
-		fn run_checks(db: &LightStorage<Block>, max: u64, checks: &[(u64, Option<Vec<AuthorityId>>)]) {
+		fn run_checks(db: &LightStorage<Block>, max: u64, checks: &[(u64, Option<Vec<AuthorityIdFor<Block>>>)]) {
 			for (at, expected) in checks.iter().take_while(|(at, _)| *at <= max) {
 				let actual = db.cache().authorities_at(BlockId::Number(*at));
 				assert_eq!(*expected, actual);
diff --git a/substrate/core/client/src/backend.rs b/substrate/core/client/src/backend.rs
index 290159bdc5..1f370f0e1b 100644
--- a/substrate/core/client/src/backend.rs
+++ b/substrate/core/client/src/backend.rs
@@ -17,9 +17,8 @@
 //! Substrate Client data backend
 
 use error;
-use primitives::AuthorityId;
 use runtime_primitives::{generic::BlockId, Justification, StorageMap, ChildrenStorageMap};
-use runtime_primitives::traits::{Block as BlockT, NumberFor};
+use runtime_primitives::traits::{AuthorityIdFor, Block as BlockT, NumberFor};
 use state_machine::backend::Backend as StateBackend;
 use state_machine::ChangesTrieStorage as StateChangesTrieStorage;
 use hash_db::Hasher;
@@ -67,7 +66,7 @@ pub trait BlockImportOperation<Block, H> where
 
 	/// Append authorities set to the transaction. This is a set of parent block (set which
 	/// has been used to check justification of this block).
-	fn update_authorities(&mut self, authorities: Vec<AuthorityId>);
+	fn update_authorities(&mut self, authorities: Vec<AuthorityIdFor<Block>>);
 	/// Inject storage data into the database.
 	fn update_storage(&mut self, update: <Self::State as StateBackend<H>>::Transaction) -> error::Result<()>;
 	/// Inject storage data into the database replacing any existing data.
diff --git a/substrate/core/client/src/blockchain.rs b/substrate/core/client/src/blockchain.rs
index ddc8ba866a..7ff395113b 100644
--- a/substrate/core/client/src/blockchain.rs
+++ b/substrate/core/client/src/blockchain.rs
@@ -16,8 +16,7 @@
 
 //! Substrate blockchain trait
 
-use primitives::AuthorityId;
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor};
+use runtime_primitives::traits::{AuthorityIdFor, Block as BlockT, Header as HeaderT, NumberFor};
 use runtime_primitives::generic::BlockId;
 use runtime_primitives::Justification;
 
@@ -90,7 +89,7 @@ pub trait Backend<Block: BlockT>: HeaderBackend<Block> {
 /// Blockchain optional data cache.
 pub trait Cache<Block: BlockT>: Send + Sync {
 	/// Returns the set of authorities, that was active at given block or None if there's no entry in the cache.
-	fn authorities_at(&self, block: BlockId<Block>) -> Option<Vec<AuthorityId>>;
+	fn authorities_at(&self, block: BlockId<Block>) -> Option<Vec<AuthorityIdFor<Block>>>;
 }
 
 /// Block import outcome
diff --git a/substrate/core/client/src/client.rs b/substrate/core/client/src/client.rs
index b0dfb939d0..79a112e616 100644
--- a/substrate/core/client/src/client.rs
+++ b/substrate/core/client/src/client.rs
@@ -20,7 +20,6 @@ use std::{marker::PhantomData, collections::{HashSet, BTreeMap}, sync::Arc};
 use error::Error;
 use futures::sync::mpsc;
 use parking_lot::{Mutex, RwLock};
-use primitives::AuthorityId;
 use runtime_primitives::{
 	Justification,
 	generic::{BlockId, SignedBlock},
@@ -28,7 +27,7 @@ use runtime_primitives::{
 use consensus::{Error as ConsensusError, ErrorKind as ConsensusErrorKind, ImportBlock, ImportResult, BlockOrigin, ForkChoiceStrategy};
 use runtime_primitives::traits::{
 	Block as BlockT, Header as HeaderT, Zero, As, NumberFor, CurrentHeight, BlockNumberToHash,
-	ApiRef, ProvideRuntimeApi, Digest, DigestItem,
+	ApiRef, ProvideRuntimeApi, Digest, DigestItem, AuthorityIdFor
 };
 use runtime_primitives::BuildStorage;
 use runtime_api::{Core as CoreAPI, CallRuntimeAt, ConstructRuntimeApi};
@@ -281,11 +280,11 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 	}
 
 	/// Get the set of authorities at a given block.
-	pub fn authorities_at(&self, id: &BlockId<Block>) -> error::Result<Vec<AuthorityId>> {
+	pub fn authorities_at(&self, id: &BlockId<Block>) -> error::Result<Vec<AuthorityIdFor<Block>>> {
 		match self.backend.blockchain().cache().and_then(|cache| cache.authorities_at(*id)) {
 			Some(cached_value) => Ok(cached_value),
 			None => self.executor.call(id, "Core_authorities", &[])
-				.and_then(|r| Vec::<AuthorityId>::decode(&mut &r.return_data[..])
+				.and_then(|r| Vec::<AuthorityIdFor<Block>>::decode(&mut &r.return_data[..])
 					.ok_or(error::ErrorKind::InvalidAuthoritiesSet.into()))
 		}
 	}
@@ -541,7 +540,7 @@ impl<B, E, Block, RA> Client<B, E, Block, RA> where
 		import_headers: PrePostHeader<Block::Header>,
 		justification: Option<Justification>,
 		body: Option<Vec<Block::Extrinsic>>,
-		authorities: Option<Vec<AuthorityId>>,
+		authorities: Option<Vec<AuthorityIdFor<Block>>>,
 		finalized: bool,
 		aux: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 		fork_choice: ForkChoiceStrategy,
@@ -1030,7 +1029,7 @@ impl<B, E, Block, RA> consensus::BlockImport<Block> for Client<B, E, Block, RA>
 	fn import_block(
 		&self,
 		import_block: ImportBlock<Block>,
-		new_authorities: Option<Vec<AuthorityId>>,
+		new_authorities: Option<Vec<AuthorityIdFor<Block>>>,
 	) -> Result<ImportResult, Self::Error> {
 		use runtime_primitives::traits::Digest;
 
@@ -1098,7 +1097,7 @@ impl<B, E, Block, RA> consensus::Authorities<Block> for Client<B, E, Block, RA>
 	Block: BlockT<Hash=H256>,
 {
 	type Error = Error;
-	fn authorities(&self, at: &BlockId<Block>) -> Result<Vec<AuthorityId>, Self::Error> {
+	fn authorities(&self, at: &BlockId<Block>) -> Result<Vec<AuthorityIdFor<Block>>, Self::Error> {
 		self.authorities_at(at).map_err(|e| e.into())
 	}
 }
diff --git a/substrate/core/client/src/in_mem.rs b/substrate/core/client/src/in_mem.rs
index 1bf50d715d..896f9821de 100644
--- a/substrate/core/client/src/in_mem.rs
+++ b/substrate/core/client/src/in_mem.rs
@@ -22,10 +22,10 @@ use parking_lot::RwLock;
 use error;
 use backend::{self, NewBlockState};
 use light;
-use primitives::{AuthorityId, storage::well_known_keys};
+use primitives::storage::well_known_keys;
 use runtime_primitives::generic::BlockId;
 use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, Zero,
-	NumberFor, As, Digest, DigestItem};
+	NumberFor, As, Digest, DigestItem, AuthorityIdFor};
 use runtime_primitives::{Justification, StorageMap, ChildrenStorageMap};
 use blockchain::{self, BlockStatus, HeaderBackend};
 use state_machine::backend::{Backend as StateBackend, InMemory, Consolidate};
@@ -108,7 +108,7 @@ pub struct Blockchain<Block: BlockT> {
 
 struct Cache<Block: BlockT> {
 	storage: Arc<RwLock<BlockchainStorage<Block>>>,
-	authorities_at: RwLock<HashMap<Block::Hash, Option<Vec<AuthorityId>>>>,
+	authorities_at: RwLock<HashMap<Block::Hash, Option<Vec<AuthorityIdFor<Block>>>>>,
 }
 
 impl<Block: BlockT + Clone> Clone for Blockchain<Block> {
@@ -368,7 +368,7 @@ impl<Block: BlockT> light::blockchain::Storage<Block> for Blockchain<Block>
 	fn import_header(
 		&self,
 		header: Block::Header,
-		authorities: Option<Vec<AuthorityId>>,
+		authorities: Option<Vec<AuthorityIdFor<Block>>>,
 		state: NewBlockState,
 		aux_ops: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 	) -> error::Result<()> {
@@ -409,7 +409,7 @@ impl<Block: BlockT> light::blockchain::Storage<Block> for Blockchain<Block>
 /// In-memory operation.
 pub struct BlockImportOperation<Block: BlockT, H: Hasher> {
 	pending_block: Option<PendingBlock<Block>>,
-	pending_authorities: Option<Vec<AuthorityId>>,
+	pending_authorities: Option<Vec<AuthorityIdFor<Block>>>,
 	old_state: InMemory<H>,
 	new_state: Option<InMemory<H>>,
 	changes_trie_update: Option<MemoryDB<H>>,
@@ -444,7 +444,7 @@ where
 		Ok(())
 	}
 
-	fn update_authorities(&mut self, authorities: Vec<AuthorityId>) {
+	fn update_authorities(&mut self, authorities: Vec<AuthorityIdFor<Block>>) {
 		self.pending_authorities = Some(authorities);
 	}
 
@@ -632,13 +632,13 @@ where
 {}
 
 impl<Block: BlockT> Cache<Block> {
-	fn insert(&self, at: Block::Hash, authorities: Option<Vec<AuthorityId>>) {
+	fn insert(&self, at: Block::Hash, authorities: Option<Vec<AuthorityIdFor<Block>>>) {
 		self.authorities_at.write().insert(at, authorities);
 	}
 }
 
 impl<Block: BlockT> blockchain::Cache<Block> for Cache<Block> {
-	fn authorities_at(&self, block: BlockId<Block>) -> Option<Vec<AuthorityId>> {
+	fn authorities_at(&self, block: BlockId<Block>) -> Option<Vec<AuthorityIdFor<Block>>> {
 		let hash = match block {
 			BlockId::Hash(hash) => hash,
 			BlockId::Number(number) => self.storage.read().hashes.get(&number).cloned()?,
@@ -652,7 +652,7 @@ impl<Block: BlockT> blockchain::Cache<Block> for Cache<Block> {
 pub fn cache_authorities_at<Block: BlockT>(
 	blockchain: &Blockchain<Block>,
 	at: Block::Hash,
-	authorities: Option<Vec<AuthorityId>>
+	authorities: Option<Vec<AuthorityIdFor<Block>>>
 ) {
 	blockchain.cache.insert(at, authorities);
 }
diff --git a/substrate/core/client/src/light/backend.rs b/substrate/core/client/src/light/backend.rs
index 185b7cfa06..79a636bfbc 100644
--- a/substrate/core/client/src/light/backend.rs
+++ b/substrate/core/client/src/light/backend.rs
@@ -21,10 +21,9 @@ use std::sync::{Arc, Weak};
 use futures::{Future, IntoFuture};
 use parking_lot::RwLock;
 
-use primitives::AuthorityId;
 use runtime_primitives::{generic::BlockId, Justification, StorageMap, ChildrenStorageMap};
 use state_machine::{Backend as StateBackend, InMemoryChangesTrieStorage, TrieBackend};
-use runtime_primitives::traits::{Block as BlockT, NumberFor};
+use runtime_primitives::traits::{Block as BlockT, NumberFor, AuthorityIdFor};
 
 use in_mem;
 use backend::{AuxStore, Backend as ClientBackend, BlockImportOperation, RemoteBackend, NewBlockState};
@@ -44,7 +43,7 @@ pub struct Backend<S, F> {
 /// Light block (header and justification) import operation.
 pub struct ImportOperation<Block: BlockT, S, F> {
 	header: Option<Block::Header>,
-	authorities: Option<Vec<AuthorityId>>,
+	authorities: Option<Vec<AuthorityIdFor<Block>>>,
 	leaf_state: NewBlockState,
 	aux_ops: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 	_phantom: ::std::marker::PhantomData<(S, F)>,
@@ -185,7 +184,7 @@ where
 		Ok(())
 	}
 
-	fn update_authorities(&mut self, authorities: Vec<AuthorityId>) {
+	fn update_authorities(&mut self, authorities: Vec<AuthorityIdFor<Block>>) {
 		self.authorities = Some(authorities);
 	}
 
diff --git a/substrate/core/client/src/light/blockchain.rs b/substrate/core/client/src/light/blockchain.rs
index ed75043164..62e40c579e 100644
--- a/substrate/core/client/src/light/blockchain.rs
+++ b/substrate/core/client/src/light/blockchain.rs
@@ -21,9 +21,8 @@ use std::sync::Weak;
 use futures::{Future, IntoFuture};
 use parking_lot::Mutex;
 
-use primitives::AuthorityId;
 use runtime_primitives::{Justification, generic::BlockId};
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT,NumberFor, Zero};
+use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, Zero, AuthorityIdFor};
 
 use backend::{AuxStore, NewBlockState};
 use blockchain::{Backend as BlockchainBackend, BlockStatus, Cache as BlockchainCache,
@@ -41,7 +40,7 @@ pub trait Storage<Block: BlockT>: AuxStore + BlockchainHeaderBackend<Block> {
 	fn import_header(
 		&self,
 		header: Block::Header,
-		authorities: Option<Vec<AuthorityId>>,
+		authorities: Option<Vec<AuthorityIdFor<Block>>>,
 		state: NewBlockState,
 		aux_ops: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 	) -> ClientResult<()>;
@@ -227,7 +226,7 @@ pub mod tests {
 		fn import_header(
 			&self,
 			_header: Header,
-			_authorities: Option<Vec<AuthorityId>>,
+			_authorities: Option<Vec<AuthorityIdFor<Block>>>,
 			_state: NewBlockState,
 			_aux_ops: Vec<(Vec<u8>, Option<Vec<u8>>)>,
 		) -> ClientResult<()> {
diff --git a/substrate/core/client/src/runtime_api.rs b/substrate/core/client/src/runtime_api.rs
index 9ad92fb493..596b355ddf 100644
--- a/substrate/core/client/src/runtime_api.rs
+++ b/substrate/core/client/src/runtime_api.rs
@@ -21,7 +21,7 @@
 pub use state_machine::OverlayedChanges;
 #[doc(hidden)]
 pub use runtime_primitives::{
-	traits::{Block as BlockT, GetNodeBlockType, GetRuntimeBlockType, ApiRef, RuntimeApiInfo},
+	traits::{AuthorityIdFor, Block as BlockT, GetNodeBlockType, GetRuntimeBlockType, ApiRef, RuntimeApiInfo},
 	generic::BlockId, transaction_validity::TransactionValidity
 };
 #[doc(hidden)]
@@ -34,7 +34,7 @@ pub use codec::{Encode, Decode};
 #[cfg(feature = "std")]
 use error;
 use rstd::vec::Vec;
-use primitives::{AuthorityId, OpaqueMetadata};
+use primitives::OpaqueMetadata;
 
 
 /// Something that can be constructed to a runtime api.
@@ -91,7 +91,7 @@ decl_runtime_apis! {
 		/// Returns the version of the runtime.
 		fn version() -> RuntimeVersion;
 		/// Returns the authorities.
-		fn authorities() -> Vec<AuthorityId>;
+		fn authorities() -> Vec<AuthorityIdFor<Block>>;
 		/// Execute the given block.
 		fn execute_block(block: Block);
 		/// Initialise a block with the given header.
diff --git a/substrate/core/consensus/aura/src/lib.rs b/substrate/core/consensus/aura/src/lib.rs
index b57dab030c..f544c2f0e7 100644
--- a/substrate/core/consensus/aura/src/lib.rs
+++ b/substrate/core/consensus/aura/src/lib.rs
@@ -67,8 +67,8 @@ use client::ChainHead;
 use client::block_builder::api::BlockBuilder as BlockBuilderApi;
 use consensus_common::{ImportBlock, BlockOrigin};
 use runtime_primitives::{generic, generic::BlockId, Justification, BasicInherentData};
-use runtime_primitives::traits::{Block, Header, Digest, DigestItemFor, ProvideRuntimeApi};
-use primitives::{AuthorityId, ed25519};
+use runtime_primitives::traits::{Block, Header, Digest, DigestItemFor, DigestItem, ProvideRuntimeApi};
+use primitives::{Ed25519AuthorityId, ed25519};
 
 use futures::{Stream, Future, IntoFuture, future::{self, Either}};
 use tokio::timer::Timeout;
@@ -91,7 +91,7 @@ pub trait Network: Clone {
 }
 
 /// Get slot author for given block along with authorities.
-fn slot_author(slot_num: u64, authorities: &[AuthorityId]) -> Option<AuthorityId> {
+fn slot_author(slot_num: u64, authorities: &[Ed25519AuthorityId]) -> Option<Ed25519AuthorityId> {
 	if authorities.is_empty() { return None }
 
 	let idx = slot_num % (authorities.len() as u64);
@@ -168,7 +168,7 @@ pub fn start_aura_thread<B, C, E, I, SO, Error>(
 	I: BlockImport<B> + Send + Sync + 'static,
 	Error: From<C::Error> + From<I::Error> + 'static,
 	SO: SyncOracle + Send + Clone + 'static,
-	DigestItemFor<B>: CompatibleDigestItem + 'static,
+	DigestItemFor<B>: CompatibleDigestItem + DigestItem<AuthorityId=Ed25519AuthorityId> + 'static,
 	Error: ::std::error::Error + Send + From<::consensus_common::Error> + 'static,
 {
 	use tokio::runtime::current_thread::Runtime;
@@ -211,7 +211,7 @@ pub fn start_aura<B, C, E, I, SO, Error>(
 	I: BlockImport<B>,
 	Error: From<C::Error> + From<I::Error>,
 	SO: SyncOracle + Send + Clone,
-	DigestItemFor<B>: CompatibleDigestItem,
+	DigestItemFor<B>: CompatibleDigestItem + DigestItem<AuthorityId=Ed25519AuthorityId>,
 	Error: ::std::error::Error + Send + 'static + From<::consensus_common::Error>,
 {
 	let make_authorship = move || {
@@ -266,7 +266,7 @@ pub fn start_aura<B, C, E, I, SO, Error>(
 							slot_num, timestamp);
 
 						// we are the slot author. make a block and sign it.
-						let proposer = match env.init(&chain_head, &authorities, pair.clone()) {
+						let proposer = match env.init(&chain_head, &authorities) {
 							Ok(p) => p,
 							Err(e) => {
 								warn!("Unable to author block in slot {:?}: {:?}", slot_num, e);
@@ -373,7 +373,7 @@ enum CheckedHeader<H> {
 /// if it's successful, returns the pre-header, the slot number, and the signat.
 //
 // FIXME: needs misbehavior types - https://github.com/paritytech/substrate/issues/1018
-fn check_header<B: Block>(slot_now: u64, mut header: B::Header, hash: B::Hash, authorities: &[AuthorityId])
+fn check_header<B: Block>(slot_now: u64, mut header: B::Header, hash: B::Hash, authorities: &[Ed25519AuthorityId])
 	-> Result<CheckedHeader<B::Header>, String>
 	where DigestItemFor<B>: CompatibleDigestItem
 {
@@ -446,7 +446,7 @@ impl<B: Block> ExtraVerification<B> for NothingExtra {
 impl<B: Block, C, E, MakeInherent, Inherent> Verifier<B> for AuraVerifier<C, E, MakeInherent> where
 	C: Authorities<B> + BlockImport<B> + ProvideRuntimeApi + Send + Sync,
 	C::Api: BlockBuilderApi<B, Inherent>,
-	DigestItemFor<B>: CompatibleDigestItem,
+	DigestItemFor<B>: CompatibleDigestItem + DigestItem<AuthorityId=Ed25519AuthorityId>,
 	E: ExtraVerification<B>,
 	MakeInherent: Fn(u64, u64) -> Inherent + Send + Sync,
 {
@@ -456,7 +456,7 @@ impl<B: Block, C, E, MakeInherent, Inherent> Verifier<B> for AuraVerifier<C, E,
 		header: B::Header,
 		justification: Option<Justification>,
 		mut body: Option<Vec<B::Extrinsic>>,
-	) -> Result<(ImportBlock<B>, Option<Vec<AuthorityId>>), String> {
+	) -> Result<(ImportBlock<B>, Option<Vec<Ed25519AuthorityId>>), String> {
 		use runtime_primitives::CheckInherentError;
 		const MAX_TIMESTAMP_DRIFT_SECS: u64 = 60;
 
@@ -600,7 +600,7 @@ pub fn import_queue<B, C, E, MakeInherent, Inherent>(
 	B: Block,
 	C: Authorities<B> + BlockImport<B,Error=ConsensusError> + ProvideRuntimeApi + Send + Sync,
 	C::Api: BlockBuilderApi<B, Inherent>,
-	DigestItemFor<B>: CompatibleDigestItem,
+	DigestItemFor<B>: CompatibleDigestItem + DigestItem<AuthorityId=Ed25519AuthorityId>,
 	E: ExtraVerification<B>,
 	MakeInherent: Fn(u64, u64) -> Inherent + Send + Sync,
 {
@@ -633,7 +633,7 @@ mod tests {
 		type Proposer = DummyProposer;
 		type Error = Error;
 
-		fn init(&self, parent_header: &<TestBlock as BlockT>::Header, _authorities: &[AuthorityId], _sign_with: Arc<ed25519::Pair>)
+		fn init(&self, parent_header: &<TestBlock as BlockT>::Header, _authorities: &[Ed25519AuthorityId])
 			-> Result<DummyProposer, Error>
 		{
 			Ok(DummyProposer(parent_header.number + 1, self.0.clone()))
diff --git a/substrate/core/consensus/common/src/block_import.rs b/substrate/core/consensus/common/src/block_import.rs
index 488112f0eb..f4a60d435d 100644
--- a/substrate/core/consensus/common/src/block_import.rs
+++ b/substrate/core/consensus/common/src/block_import.rs
@@ -16,8 +16,7 @@
 
 //! Block import helpers.
 
-use primitives::AuthorityId;
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, DigestItemFor};
+use runtime_primitives::traits::{AuthorityIdFor, Block as BlockT, Header as HeaderT, DigestItemFor};
 use runtime_primitives::Justification;
 use std::borrow::Cow;
 
@@ -146,6 +145,6 @@ pub trait BlockImport<B: BlockT> {
 	/// Import a Block alongside the new authorities valid form this block forward
 	fn import_block(&self,
 		block: ImportBlock<B>,
-		new_authorities: Option<Vec<AuthorityId>>
+		new_authorities: Option<Vec<AuthorityIdFor<B>>>
 	) -> Result<ImportResult, Self::Error>;
 }
diff --git a/substrate/core/consensus/common/src/error.rs b/substrate/core/consensus/common/src/error.rs
index 14a3fb81e1..ec378d24cb 100644
--- a/substrate/core/consensus/common/src/error.rs
+++ b/substrate/core/consensus/common/src/error.rs
@@ -44,13 +44,13 @@ error_chain! {
 		}
 
 		/// Error checking signature
-		InvalidSignature(s: ::primitives::ed25519::Signature, a: ::primitives::AuthorityId) {
+		InvalidSignature(s: ::primitives::ed25519::Signature, a: ::primitives::Ed25519AuthorityId) {
 			description("Message signature is invalid"),
 			display("Message signature {:?} by {:?} is invalid.", s, a),
 		}
 
 		/// Account is not an authority.
-		InvalidAuthority(a: ::primitives::AuthorityId) {
+		InvalidAuthority(a: ::primitives::Ed25519AuthorityId) {
 			description("Message sender is not a valid authority"),
 			display("Message sender {:?} is not a valid authority.", a),
 		}
diff --git a/substrate/core/consensus/common/src/import_queue.rs b/substrate/core/consensus/common/src/import_queue.rs
index 3a048f781a..5264b29cef 100644
--- a/substrate/core/consensus/common/src/import_queue.rs
+++ b/substrate/core/consensus/common/src/import_queue.rs
@@ -29,10 +29,9 @@ use std::collections::{HashSet, VecDeque};
 use std::sync::Arc;
 use std::sync::atomic::{AtomicBool, Ordering};
 use parking_lot::{Condvar, Mutex, RwLock};
-use primitives::AuthorityId;
 
 use runtime_primitives::Justification;
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, Zero};
+use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor, Zero, AuthorityIdFor};
 
 use error::Error as ConsensusError;
 
@@ -68,7 +67,7 @@ pub trait Verifier<B: BlockT>: Send + Sync + Sized {
 		header: B::Header,
 		justification: Option<Justification>,
 		body: Option<Vec<B::Extrinsic>>
-	) -> Result<(ImportBlock<B>, Option<Vec<AuthorityId>>), String>;
+	) -> Result<(ImportBlock<B>, Option<Vec<AuthorityIdFor<B>>>), String>;
 }
 
 /// Blocks import queue API.
diff --git a/substrate/core/consensus/common/src/lib.rs b/substrate/core/consensus/common/src/lib.rs
index e9b5d82951..23bde0c056 100644
--- a/substrate/core/consensus/common/src/lib.rs
+++ b/substrate/core/consensus/common/src/lib.rs
@@ -40,9 +40,8 @@ extern crate error_chain;
 
 use std::sync::Arc;
 
-use primitives::{ed25519, AuthorityId};
 use runtime_primitives::generic::BlockId;
-use runtime_primitives::traits::Block;
+use runtime_primitives::traits::{AuthorityIdFor, Block};
 use futures::prelude::*;
 
 pub mod offline_tracker;
@@ -60,7 +59,7 @@ pub use block_import::{BlockImport, ImportBlock, BlockOrigin, ImportResult, Fork
 /// Trait for getting the authorities at a given block.
 pub trait Authorities<B: Block> {
 	type Error: ::std::error::Error + Send + 'static;	/// Get the authorities at the given block.
-	fn authorities(&self, at: &BlockId<B>) -> Result<Vec<AuthorityId>, Self::Error>;
+	fn authorities(&self, at: &BlockId<B>) -> Result<Vec<AuthorityIdFor<B>>, Self::Error>;
 }
 
 /// Environment producer for a Consensus instance. Creates proposer instance and communication streams.
@@ -71,9 +70,8 @@ pub trait Environment<B: Block, ConsensusData> {
 	type Error: From<Error>;
 
 	/// Initialize the proposal logic on top of a specific header. Provide
-	/// the authorities at that header, and a local key to sign any additional
-	/// consensus messages with as well.
-	fn init(&self, parent_header: &B::Header, authorities: &[AuthorityId], sign_with: Arc<ed25519::Pair>)
+	/// the authorities at that header.
+	fn init(&self, parent_header: &B::Header, authorities: &[AuthorityIdFor<B>])
 		-> Result<Self::Proposer, Self::Error>;
 }
 
diff --git a/substrate/core/consensus/common/src/offline_tracker.rs b/substrate/core/consensus/common/src/offline_tracker.rs
index bd8eab8b1b..1ed923da2c 100644
--- a/substrate/core/consensus/common/src/offline_tracker.rs
+++ b/substrate/core/consensus/common/src/offline_tracker.rs
@@ -16,8 +16,6 @@
 
 //! Tracks offline validators.
 
-use primitives::AuthorityId;
-
 use std::collections::HashMap;
 use std::time::{Instant, Duration};
 
@@ -55,11 +53,11 @@ impl Observed {
 }
 
 /// Tracks offline validators and can issue a report for those offline.
-pub struct OfflineTracker {
+pub struct OfflineTracker<AuthorityId> {
 	observed: HashMap<AuthorityId, Observed>,
 }
 
-impl OfflineTracker {
+impl<AuthorityId: Eq + Clone + std::hash::Hash> OfflineTracker<AuthorityId> {
 	/// Create a new tracker.
 	pub fn new() -> Self {
 		OfflineTracker { observed: HashMap::new() }
@@ -114,10 +112,11 @@ impl OfflineTracker {
 #[cfg(test)]
 mod tests {
 	use super::*;
+	use primitives::Ed25519AuthorityId;
 
 	#[test]
 	fn validator_offline() {
-		let mut tracker = OfflineTracker::new();
+		let mut tracker = OfflineTracker::<Ed25519AuthorityId>::new();
 		let v = [0; 32].into();
 		let v2 = [1; 32].into();
 		let v3 = [2; 32].into();
diff --git a/substrate/core/finality-grandpa/primitives/src/lib.rs b/substrate/core/finality-grandpa/primitives/src/lib.rs
index df224fa9d4..15e4a027f6 100644
--- a/substrate/core/finality-grandpa/primitives/src/lib.rs
+++ b/substrate/core/finality-grandpa/primitives/src/lib.rs
@@ -34,7 +34,7 @@ extern crate substrate_client as client;
 
 extern crate sr_std as rstd;
 
-use substrate_primitives::AuthorityId;
+use substrate_primitives::Ed25519AuthorityId;
 use sr_primitives::traits::{DigestFor, NumberFor};
 use rstd::vec::Vec;
 
@@ -43,7 +43,7 @@ use rstd::vec::Vec;
 #[derive(Clone, Encode, Decode)]
 pub struct ScheduledChange<N> {
 	/// The new authorities after the change, along with their respective weights.
-	pub next_authorities: Vec<(AuthorityId, u64)>,
+	pub next_authorities: Vec<(Ed25519AuthorityId, u64)>,
 	/// The number of blocks to delay.
 	pub delay: N,
 }
@@ -97,6 +97,6 @@ decl_runtime_apis! {
 
 		/// Get the current GRANDPA authorities and weights. This should not change except
 		/// for when changes are scheduled and the corresponding delay has passed.
-		fn grandpa_authorities() -> Vec<(AuthorityId, u64)>;
+		fn grandpa_authorities() -> Vec<(Ed25519AuthorityId, u64)>;
 	}
 }
diff --git a/substrate/core/finality-grandpa/src/authorities.rs b/substrate/core/finality-grandpa/src/authorities.rs
index 64e9f36906..ca9bd61a88 100644
--- a/substrate/core/finality-grandpa/src/authorities.rs
+++ b/substrate/core/finality-grandpa/src/authorities.rs
@@ -17,7 +17,7 @@
 //! Utilities for dealing with authorities, authority sets, and handoffs.
 
 use parking_lot::RwLock;
-use substrate_primitives::AuthorityId;
+use substrate_primitives::Ed25519AuthorityId;
 
 use std::cmp::Ord;
 use std::collections::HashMap;
@@ -38,7 +38,7 @@ impl<H, N> Clone for SharedAuthoritySet<H, N> {
 
 impl<H, N> SharedAuthoritySet<H, N> {
 	/// The genesis authority set.
-	pub(crate) fn genesis(initial: Vec<(AuthorityId, u64)>) -> Self {
+	pub(crate) fn genesis(initial: Vec<(Ed25519AuthorityId, u64)>) -> Self {
 		SharedAuthoritySet {
 			inner: Arc::new(RwLock::new(AuthoritySet::genesis(initial)))
 		}
@@ -66,7 +66,7 @@ where
 	}
 
 	/// Get the current authorities and their weights (for the current set ID).
-	pub(crate) fn current_authorities(&self) -> HashMap<AuthorityId, u64> {
+	pub(crate) fn current_authorities(&self) -> HashMap<Ed25519AuthorityId, u64> {
 		self.inner.read().current_authorities.iter().cloned().collect()
 	}
 }
@@ -89,14 +89,14 @@ pub(crate) struct Status<H, N> {
 /// A set of authorities.
 #[derive(Debug, Clone, Encode, Decode)]
 pub(crate) struct AuthoritySet<H, N> {
-	current_authorities: Vec<(AuthorityId, u64)>,
+	current_authorities: Vec<(Ed25519AuthorityId, u64)>,
 	set_id: u64,
 	pending_changes: Vec<PendingChange<H, N>>,
 }
 
 impl<H, N> AuthoritySet<H, N> {
 	/// Get a genesis set with given authorities.
-	pub(crate) fn genesis(initial: Vec<(AuthorityId, u64)>) -> Self {
+	pub(crate) fn genesis(initial: Vec<(Ed25519AuthorityId, u64)>) -> Self {
 		AuthoritySet {
 			current_authorities: initial,
 			set_id: 0,
@@ -105,7 +105,7 @@ impl<H, N> AuthoritySet<H, N> {
 	}
 
 	/// Get the current set id and a reference to the current authority set.
-	pub(crate) fn current(&self) -> (u64, &[(AuthorityId, u64)]) {
+	pub(crate) fn current(&self) -> (u64, &[(Ed25519AuthorityId, u64)]) {
 		(self.set_id, &self.current_authorities[..])
 	}
 }
@@ -249,7 +249,7 @@ where
 #[derive(Debug, Clone, Encode, Decode, PartialEq)]
 pub(crate) struct PendingChange<H, N> {
 	/// The new authorities and weights to apply.
-	pub(crate) next_authorities: Vec<(AuthorityId, u64)>,
+	pub(crate) next_authorities: Vec<(Ed25519AuthorityId, u64)>,
 	/// How deep in the finalized chain the announcing block must be
 	/// before the change is applied.
 	pub(crate) finalization_depth: N,
diff --git a/substrate/core/finality-grandpa/src/communication.rs b/substrate/core/finality-grandpa/src/communication.rs
index 02a079b909..b8435cef6c 100644
--- a/substrate/core/finality-grandpa/src/communication.rs
+++ b/substrate/core/finality-grandpa/src/communication.rs
@@ -20,7 +20,7 @@
 use futures::prelude::*;
 use futures::sync::mpsc;
 use codec::{Encode, Decode};
-use substrate_primitives::{ed25519, AuthorityId};
+use substrate_primitives::{ed25519, Ed25519AuthorityId};
 use runtime_primitives::traits::Block as BlockT;
 use {Error, Network, Message, SignedMessage, Commit, CompactCommit};
 
@@ -34,7 +34,7 @@ fn localized_payload<E: Encode>(round: u64, set_id: u64, message: &E) -> Vec<u8>
 // check a message.
 pub(crate) fn check_message_sig<Block: BlockT>(
 	message: &Message<Block>,
-	id: &AuthorityId,
+	id: &Ed25519AuthorityId,
 	signature: &ed25519::Signature,
 	round: u64,
 	set_id: u64,
@@ -55,7 +55,7 @@ pub(crate) fn checked_message_stream<Block: BlockT, S>(
 	round: u64,
 	set_id: u64,
 	inner: S,
-	voters: Arc<HashMap<AuthorityId, u64>>,
+	voters: Arc<HashMap<Ed25519AuthorityId, u64>>,
 )
 	-> impl Stream<Item=SignedMessage<Block>,Error=Error> where
 	S: Stream<Item=Vec<u8>,Error=()>
@@ -92,7 +92,7 @@ pub(crate) fn checked_message_stream<Block: BlockT, S>(
 struct OutgoingMessages<Block: BlockT, N: Network> {
 	round: u64,
 	set_id: u64,
-	locals: Option<(Arc<ed25519::Pair>, AuthorityId)>,
+	locals: Option<(Arc<ed25519::Pair>, Ed25519AuthorityId)>,
 	sender: mpsc::UnboundedSender<SignedMessage<Block>>,
 	network: N,
 }
@@ -143,7 +143,7 @@ pub(crate) fn outgoing_messages<Block: BlockT, N: Network>(
 	round: u64,
 	set_id: u64,
 	local_key: Option<Arc<ed25519::Pair>>,
-	voters: Arc<HashMap<AuthorityId, u64>>,
+	voters: Arc<HashMap<Ed25519AuthorityId, u64>>,
 	network: N,
 ) -> (
 	impl Stream<Item=SignedMessage<Block>,Error=Error>,
@@ -151,7 +151,7 @@ pub(crate) fn outgoing_messages<Block: BlockT, N: Network>(
 ) {
 	let locals = local_key.and_then(|pair| {
 		let public = pair.public();
-		let id = AuthorityId(public.0);
+		let id = Ed25519AuthorityId(public.0);
 		if voters.contains_key(&id) {
 			Some((pair, id))
 		} else {
@@ -177,7 +177,7 @@ pub(crate) fn outgoing_messages<Block: BlockT, N: Network>(
 
 fn check_compact_commit<Block: BlockT>(
 	msg: CompactCommit<Block>,
-	voters: &HashMap<AuthorityId, u64>,
+	voters: &HashMap<Ed25519AuthorityId, u64>,
 	round: u64,
 	set_id: u64,
 ) -> Option<CompactCommit<Block>> {
@@ -216,7 +216,7 @@ fn check_compact_commit<Block: BlockT>(
 pub(crate) fn checked_commit_stream<Block: BlockT, S>(
 	set_id: u64,
 	inner: S,
-	voters: Arc<HashMap<AuthorityId, u64>>,
+	voters: Arc<HashMap<Ed25519AuthorityId, u64>>,
 )
 	-> impl Stream<Item=(u64, CompactCommit<Block>),Error=Error> where
 	S: Stream<Item=Vec<u8>,Error=()>
diff --git a/substrate/core/finality-grandpa/src/lib.rs b/substrate/core/finality-grandpa/src/lib.rs
index abd737d357..00ea6734af 100644
--- a/substrate/core/finality-grandpa/src/lib.rs
+++ b/substrate/core/finality-grandpa/src/lib.rs
@@ -92,10 +92,11 @@ use codec::{Encode, Decode};
 use consensus_common::{BlockImport, Error as ConsensusError, ErrorKind as ConsensusErrorKind, ImportBlock, ImportResult, Authorities};
 use runtime_primitives::traits::{
 	NumberFor, Block as BlockT, Header as HeaderT, DigestFor, ProvideRuntimeApi, Hash as HashT,
+	DigestItemFor, DigestItem,
 };
 use fg_primitives::GrandpaApi;
 use runtime_primitives::generic::BlockId;
-use substrate_primitives::{ed25519, H256, AuthorityId, Blake2Hasher};
+use substrate_primitives::{ed25519, H256, Ed25519AuthorityId, Blake2Hasher};
 use tokio::timer::Delay;
 
 use grandpa::Error as GrandpaError;
@@ -138,7 +139,7 @@ pub type SignedMessage<Block> = grandpa::SignedMessage<
 	<Block as BlockT>::Hash,
 	NumberFor<Block>,
 	ed25519::Signature,
-	AuthorityId,
+	Ed25519AuthorityId,
 >;
 /// A prevote message for this chain's block type.
 pub type Prevote<Block> = grandpa::Prevote<<Block as BlockT>::Hash, NumberFor<Block>>;
@@ -149,14 +150,14 @@ pub type Commit<Block> = grandpa::Commit<
 	<Block as BlockT>::Hash,
 	NumberFor<Block>,
 	ed25519::Signature,
-	AuthorityId
+	Ed25519AuthorityId
 >;
 /// A compact commit message for this chain's block type.
 pub type CompactCommit<Block> = grandpa::CompactCommit<
 	<Block as BlockT>::Hash,
 	NumberFor<Block>,
 	ed25519::Signature,
-	AuthorityId
+	Ed25519AuthorityId
 >;
 
 /// Configuration for the GRANDPA service.
@@ -306,7 +307,7 @@ impl<B, E, Block: BlockT<Hash=H256>, RA> BlockStatus<Block> for Arc<Client<B, E,
 /// The environment we run GRANDPA in.
 struct Environment<B, E, Block: BlockT, N: Network, RA> {
 	inner: Arc<Client<B, E, Block, RA>>,
-	voters: Arc<HashMap<AuthorityId, u64>>,
+	voters: Arc<HashMap<Ed25519AuthorityId, u64>>,
 	config: Config,
 	authority_set: SharedAuthoritySet<Block::Hash, NumberFor<Block>>,
 	network: N,
@@ -381,7 +382,7 @@ struct NewAuthoritySet<H, N> {
 	canon_number: N,
 	canon_hash: H,
 	set_id: u64,
-	authorities: Vec<(AuthorityId, u64)>,
+	authorities: Vec<(Ed25519AuthorityId, u64)>,
 }
 
 /// Signals either an early exit of a voter or an error.
@@ -432,7 +433,7 @@ impl<B, E, Block: BlockT<Hash=H256>, N, RA> voter::Environment<Block::Hash, Numb
 	NumberFor<Block>: BlockNumberOps,
 {
 	type Timer = Box<dyn Future<Item = (), Error = Self::Error> + Send>;
-	type Id = AuthorityId;
+	type Id = Ed25519AuthorityId;
 	type Signature = ed25519::Signature;
 
 	// regular round message streams
@@ -611,7 +612,7 @@ impl<Block: BlockT<Hash=H256>> GrandpaJustification<Block> {
 	fn decode_and_verify(
 		encoded: Vec<u8>,
 		set_id: u64,
-		voters: &HashMap<AuthorityId, u64>,
+		voters: &HashMap<Ed25519AuthorityId, u64>,
 	) -> Result<GrandpaJustification<Block>, ClientError> where
 		NumberFor<Block>: grandpa::BlockNumberOps,
 	{
@@ -830,13 +831,14 @@ impl<B, E, Block: BlockT<Hash=H256>, RA, PRA> BlockImport<Block>
 		B: Backend<Block, Blake2Hasher> + 'static,
 		E: CallExecutor<Block, Blake2Hasher> + 'static + Clone + Send + Sync,
 		DigestFor<Block>: Encode,
+		DigestItemFor<Block>: DigestItem<AuthorityId=Ed25519AuthorityId>,
 		RA: Send + Sync,
 		PRA: ProvideRuntimeApi,
 		PRA::Api: GrandpaApi<Block>,
 {
 	type Error = ConsensusError;
 
-	fn import_block(&self, mut block: ImportBlock<Block>, new_authorities: Option<Vec<AuthorityId>>)
+	fn import_block(&self, mut block: ImportBlock<Block>, new_authorities: Option<Vec<Ed25519AuthorityId>>)
 		-> Result<ImportResult, Self::Error>
 	{
 		use authorities::PendingChange;
@@ -1030,10 +1032,11 @@ impl<B, E, Block: BlockT<Hash=H256>, RA, PRA> Authorities<Block> for GrandpaBloc
 where
 	B: Backend<Block, Blake2Hasher> + 'static,
 	E: CallExecutor<Block, Blake2Hasher> + 'static + Clone + Send + Sync,
+	DigestItemFor<Block>: DigestItem<AuthorityId=Ed25519AuthorityId>,
 {
 
 	type Error = <Client<B, E, Block, RA> as Authorities<Block>>::Error;
-	fn authorities(&self, at: &BlockId<Block>) -> Result<Vec<AuthorityId>, Self::Error> {
+	fn authorities(&self, at: &BlockId<Block>) -> Result<Vec<Ed25519AuthorityId>, Self::Error> {
 		self.inner.authorities_at(at)
 	}
 }
@@ -1158,16 +1161,16 @@ pub fn block_import<B, E, Block: BlockT<Hash=H256>, RA, PRA>(
 
 fn committer_communication<Block: BlockT<Hash=H256>, B, E, N, RA>(
 	set_id: u64,
-	voters: &Arc<HashMap<AuthorityId, u64>>,
+	voters: &Arc<HashMap<Ed25519AuthorityId, u64>>,
 	client: &Arc<Client<B, E, Block, RA>>,
 	network: &N,
 ) -> (
 	impl Stream<
-		Item = (u64, ::grandpa::CompactCommit<H256, NumberFor<Block>, ed25519::Signature, AuthorityId>),
+		Item = (u64, ::grandpa::CompactCommit<H256, NumberFor<Block>, ed25519::Signature, Ed25519AuthorityId>),
 		Error = ExitOrError<H256, NumberFor<Block>>,
 	>,
 	impl Sink<
-		SinkItem = (u64, ::grandpa::Commit<H256, NumberFor<Block>, ed25519::Signature, AuthorityId>),
+		SinkItem = (u64, ::grandpa::Commit<H256, NumberFor<Block>, ed25519::Signature, Ed25519AuthorityId>),
 		SinkError = ExitOrError<H256, NumberFor<Block>>,
 	>,
 ) where
@@ -1176,6 +1179,7 @@ fn committer_communication<Block: BlockT<Hash=H256>, B, E, N, RA>(
 	N: Network,
 	RA: Send + Sync,
 	NumberFor<Block>: BlockNumberOps,
+	DigestItemFor<Block>: DigestItem<AuthorityId=Ed25519AuthorityId>,
 {
 	// verification stream
 	let commit_in = ::communication::checked_commit_stream::<Block, _>(
@@ -1217,6 +1221,7 @@ pub fn run_grandpa<B, E, Block: BlockT<Hash=H256>, N, RA>(
 	N::In: Send + 'static,
 	NumberFor<Block>: BlockNumberOps,
 	DigestFor<Block>: Encode,
+	DigestItemFor<Block>: DigestItem<AuthorityId=Ed25519AuthorityId>,
 	RA: Send + Sync + 'static,
 {
 	use futures::future::{self, Loop as FutureLoop};
diff --git a/substrate/core/finality-grandpa/src/tests.rs b/substrate/core/finality-grandpa/src/tests.rs
index a357fa81da..18bfaef1a5 100644
--- a/substrate/core/finality-grandpa/src/tests.rs
+++ b/substrate/core/finality-grandpa/src/tests.rs
@@ -230,12 +230,12 @@ impl Network for MessageRouting {
 
 #[derive(Default, Clone)]
 struct TestApi {
-	genesis_authorities: Vec<(AuthorityId, u64)>,
+	genesis_authorities: Vec<(Ed25519AuthorityId, u64)>,
 	scheduled_changes: Arc<Mutex<HashMap<Hash, ScheduledChange<BlockNumber>>>>,
 }
 
 impl TestApi {
-	fn new(genesis_authorities: Vec<(AuthorityId, u64)>) -> Self {
+	fn new(genesis_authorities: Vec<(Ed25519AuthorityId, u64)>) -> Self {
 		TestApi {
 			genesis_authorities,
 			scheduled_changes: Arc::new(Mutex::new(HashMap::new())),
@@ -260,7 +260,7 @@ impl Core<Block> for RuntimeApi {
 		unimplemented!("Not required for testing!")
 	}
 
-	fn authorities(&self, _: &BlockId<Block>) -> Result<Vec<AuthorityId>> {
+	fn authorities(&self, _: &BlockId<Block>) -> Result<Vec<Ed25519AuthorityId>> {
 		unimplemented!("Not required for testing!")
 	}
 
@@ -300,7 +300,7 @@ impl GrandpaApi<Block> for RuntimeApi {
 	fn grandpa_authorities(
 		&self,
 		at: &BlockId<Block>
-	) -> Result<Vec<(AuthorityId, u64)>> {
+	) -> Result<Vec<(Ed25519AuthorityId, u64)>> {
 		if at == &BlockId::Number(0) {
 			Ok(self.inner.genesis_authorities.clone())
 		} else {
@@ -325,9 +325,9 @@ impl GrandpaApi<Block> for RuntimeApi {
 const TEST_GOSSIP_DURATION: Duration = Duration::from_millis(500);
 const TEST_ROUTING_INTERVAL: Duration = Duration::from_millis(50);
 
-fn make_ids(keys: &[Keyring]) -> Vec<(AuthorityId, u64)> {
+fn make_ids(keys: &[Keyring]) -> Vec<(Ed25519AuthorityId, u64)> {
 	keys.iter()
-		.map(|key| AuthorityId(key.to_raw_public()))
+		.map(|key| Ed25519AuthorityId(key.to_raw_public()))
 		.map(|id| (id, 1))
 		.collect()
 }
diff --git a/substrate/core/finality-grandpa/src/until_imported.rs b/substrate/core/finality-grandpa/src/until_imported.rs
index 028b710acb..8cb825ac84 100644
--- a/substrate/core/finality-grandpa/src/until_imported.rs
+++ b/substrate/core/finality-grandpa/src/until_imported.rs
@@ -27,7 +27,7 @@ use futures::prelude::*;
 use futures::stream::Fuse;
 use parking_lot::Mutex;
 use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, NumberFor};
-use substrate_primitives::AuthorityId;
+use substrate_primitives::Ed25519AuthorityId;
 use tokio::timer::Interval;
 
 use std::collections::{HashMap, VecDeque};
@@ -181,7 +181,7 @@ impl<Block: BlockT, Status, I, M> Stream for UntilImported<Block, Status, I, M>
 	}
 }
 
-fn warn_authority_wrong_target<H: ::std::fmt::Display>(hash: H, id: AuthorityId) {
+fn warn_authority_wrong_target<H: ::std::fmt::Display>(hash: H, id: Ed25519AuthorityId) {
 	warn!(
 		target: "afg",
 		"Authority {:?} signed GRANDPA message with \
diff --git a/substrate/core/network/src/chain.rs b/substrate/core/network/src/chain.rs
index 166dfe55a7..457f8852b2 100644
--- a/substrate/core/network/src/chain.rs
+++ b/substrate/core/network/src/chain.rs
@@ -20,16 +20,16 @@ use client::{self, Client as SubstrateClient, ClientInfo, BlockStatus, CallExecu
 use client::error::Error;
 use client::light::fetcher::ChangesProof;
 use consensus::{BlockImport, Error as ConsensusError};
-use runtime_primitives::traits::{Block as BlockT, Header as HeaderT};
+use runtime_primitives::traits::{Block as BlockT, Header as HeaderT, AuthorityIdFor};
 use runtime_primitives::generic::{BlockId};
 use consensus::{ImportBlock, ImportResult};
 use runtime_primitives::Justification;
-use primitives::{H256, Blake2Hasher, AuthorityId};
+use primitives::{H256, Blake2Hasher};
 
 /// Local client abstraction for the network.
 pub trait Client<Block: BlockT>: Send + Sync {
 	/// Import a new block. Parent is supposed to be existing in the blockchain.
-	fn import(&self, block: ImportBlock<Block>, new_authorities: Option<Vec<AuthorityId>>)
+	fn import(&self, block: ImportBlock<Block>, new_authorities: Option<Vec<AuthorityIdFor<Block>>>)
 		-> Result<ImportResult, ConsensusError>;
 
 	/// Get blockchain info.
@@ -77,7 +77,7 @@ impl<B, E, Block, RA> Client<Block> for SubstrateClient<B, E, Block, RA> where
 	Block: BlockT<Hash=H256>,
 	RA: Send + Sync
 {
-	fn import(&self, block: ImportBlock<Block>, new_authorities: Option<Vec<AuthorityId>>)
+	fn import(&self, block: ImportBlock<Block>, new_authorities: Option<Vec<AuthorityIdFor<Block>>>)
 		-> Result<ImportResult, ConsensusError>
 	{
 		(self as &SubstrateClient<B, E, Block, RA>).import_block(block, new_authorities)
diff --git a/substrate/core/network/src/test/mod.rs b/substrate/core/network/src/test/mod.rs
index 94518978bc..48b401b21a 100644
--- a/substrate/core/network/src/test/mod.rs
+++ b/substrate/core/network/src/test/mod.rs
@@ -29,9 +29,8 @@ use client;
 use client::block_builder::BlockBuilder;
 use runtime_primitives::Justification;
 use runtime_primitives::generic::BlockId;
-use runtime_primitives::traits::{Block as BlockT, Zero};
+use runtime_primitives::traits::{Block as BlockT, Zero, AuthorityIdFor};
 use io::SyncIo;
-use primitives::AuthorityId;
 use protocol::{Context, Protocol, ProtocolContext};
 use config::ProtocolConfig;
 use service::{NetworkLink, TransactionPool};
@@ -92,7 +91,7 @@ impl<B: BlockT> Verifier<B> for PassThroughVerifier {
 		header: B::Header,
 		justification: Option<Justification>,
 		body: Option<Vec<B::Extrinsic>>
-	) -> Result<(ImportBlock<B>, Option<Vec<AuthorityId>>), String> {
+	) -> Result<(ImportBlock<B>, Option<Vec<AuthorityIdFor<B>>>), String> {
 		Ok((ImportBlock {
 			origin,
 			header,
diff --git a/substrate/core/primitives/src/authority_id.rs b/substrate/core/primitives/src/authority_id.rs
index 9a6abf1f03..7773e1a930 100644
--- a/substrate/core/primitives/src/authority_id.rs
+++ b/substrate/core/primitives/src/authority_id.rs
@@ -20,17 +20,17 @@ use H256;
 
 /// An identifier for an authority in the consensus algorithm. The same size as ed25519::Public.
 #[derive(Clone, Copy, PartialEq, Eq, Default, Encode, Decode)]
-pub struct AuthorityId(pub [u8; 32]);
+pub struct Ed25519AuthorityId(pub [u8; 32]);
 
 #[cfg(feature = "std")]
-impl ::std::fmt::Display for AuthorityId {
+impl ::std::fmt::Display for Ed25519AuthorityId {
 	fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
 		write!(f, "{}", ::ed25519::Public(self.0).to_ss58check())
 	}
 }
 
 #[cfg(feature = "std")]
-impl ::std::fmt::Debug for AuthorityId {
+impl ::std::fmt::Debug for Ed25519AuthorityId {
 	fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
 		let h = format!("{}", ::hexdisplay::HexDisplay::from(&self.0));
 		write!(f, "{} ({}…{})", ::ed25519::Public(self.0).to_ss58check(), &h[0..8], &h[60..])
@@ -38,57 +38,57 @@ impl ::std::fmt::Debug for AuthorityId {
 }
 
 #[cfg(feature = "std")]
-impl ::std::hash::Hash for AuthorityId {
+impl ::std::hash::Hash for Ed25519AuthorityId {
 	fn hash<H: ::std::hash::Hasher>(&self, state: &mut H) {
 		self.0.hash(state);
 	}
 }
 
-impl AsRef<[u8; 32]> for AuthorityId {
+impl AsRef<[u8; 32]> for Ed25519AuthorityId {
 	fn as_ref(&self) -> &[u8; 32] {
 		&self.0
 	}
 }
 
-impl AsRef<[u8]> for AuthorityId {
+impl AsRef<[u8]> for Ed25519AuthorityId {
 	fn as_ref(&self) -> &[u8] {
 		&self.0[..]
 	}
 }
 
-impl Into<[u8; 32]> for AuthorityId {
+impl Into<[u8; 32]> for Ed25519AuthorityId {
 	fn into(self) -> [u8; 32] {
 		self.0
 	}
 }
 
-impl From<[u8; 32]> for AuthorityId {
+impl From<[u8; 32]> for Ed25519AuthorityId {
 	fn from(a: [u8; 32]) -> Self {
-		AuthorityId(a)
+		Ed25519AuthorityId(a)
 	}
 }
 
-impl AsRef<AuthorityId> for AuthorityId {
-	fn as_ref(&self) -> &AuthorityId {
+impl AsRef<Ed25519AuthorityId> for Ed25519AuthorityId {
+	fn as_ref(&self) -> &Ed25519AuthorityId {
 		&self
 	}
 }
 
-impl Into<H256> for AuthorityId {
+impl Into<H256> for Ed25519AuthorityId {
 	fn into(self) -> H256 {
 		self.0.into()
 	}
 }
 
 #[cfg(feature = "std")]
-impl Serialize for AuthorityId {
+impl Serialize for Ed25519AuthorityId {
 	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> where S: Serializer {
 		::ed25519::serialize(&self, serializer)
 	}
 }
 
 #[cfg(feature = "std")]
-impl<'de> Deserialize<'de> for AuthorityId {
+impl<'de> Deserialize<'de> for Ed25519AuthorityId {
 	fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de> {
 		::ed25519::deserialize(deserializer)
 	}
diff --git a/substrate/core/primitives/src/ed25519.rs b/substrate/core/primitives/src/ed25519.rs
index c6f28c64c1..05077fbd37 100644
--- a/substrate/core/primitives/src/ed25519.rs
+++ b/substrate/core/primitives/src/ed25519.rs
@@ -21,7 +21,7 @@
 use untrusted;
 use blake2_rfc;
 use ring::{rand, signature};
-use {hash::H512, AuthorityId};
+use {hash::H512, Ed25519AuthorityId};
 use base58::{ToBase58, FromBase58};
 
 #[cfg(feature = "std")]
@@ -169,14 +169,14 @@ impl AsRef<Pair> for Pair {
 	}
 }
 
-impl Into<AuthorityId> for Public {
-	fn into(self) -> AuthorityId {
-		AuthorityId(self.0)
+impl Into<Ed25519AuthorityId> for Public {
+	fn into(self) -> Ed25519AuthorityId {
+		Ed25519AuthorityId(self.0)
 	}
 }
 
-impl From<AuthorityId> for Public {
-	fn from(id: AuthorityId) -> Self {
+impl From<Ed25519AuthorityId> for Public {
+	fn from(id: Ed25519AuthorityId) -> Self {
 		Public(id.0)
 	}
 }
diff --git a/substrate/core/primitives/src/lib.rs b/substrate/core/primitives/src/lib.rs
index 83f6a8d0bc..98289ddc18 100644
--- a/substrate/core/primitives/src/lib.rs
+++ b/substrate/core/primitives/src/lib.rs
@@ -109,7 +109,7 @@ mod tests;
 
 pub use self::hash::{H160, H256, H512, convert_hash};
 pub use self::uint::U256;
-pub use authority_id::AuthorityId;
+pub use authority_id::Ed25519AuthorityId;
 pub use changes_trie::ChangesTrieConfiguration;
 
 pub use hash_db::Hasher;
diff --git a/substrate/core/sr-api-macros/tests/decl_and_impl.rs b/substrate/core/sr-api-macros/tests/decl_and_impl.rs
index 47822e538b..699c8c01cf 100644
--- a/substrate/core/sr-api-macros/tests/decl_and_impl.rs
+++ b/substrate/core/sr-api-macros/tests/decl_and_impl.rs
@@ -4,9 +4,8 @@ extern crate sr_primitives as runtime_primitives;
 extern crate substrate_primitives as primitives;
 extern crate substrate_test_client as test_client;
 
-use runtime_primitives::traits::{GetNodeBlockType, Block as BlockT};
+use runtime_primitives::traits::{GetNodeBlockType, Block as BlockT, AuthorityIdFor};
 use runtime_primitives::generic::BlockId;
-use primitives::AuthorityId;
 use substrate_client::runtime_api::{self, RuntimeApiInfo};
 use substrate_client::error::Result;
 use test_client::runtime::Block;
@@ -57,7 +56,7 @@ impl_runtime_apis! {
 		fn version() -> runtime_api::RuntimeVersion {
 			unimplemented!()
 		}
-		fn authorities() -> Vec<AuthorityId> {
+		fn authorities() -> Vec<AuthorityIdFor<Block>> {
 			unimplemented!()
 		}
 		fn execute_block(_: Block) {
diff --git a/substrate/core/sr-primitives/src/generic/digest.rs b/substrate/core/sr-primitives/src/generic/digest.rs
index 1bf53a9c01..f2185c23db 100644
--- a/substrate/core/sr-primitives/src/generic/digest.rs
+++ b/substrate/core/sr-primitives/src/generic/digest.rs
@@ -19,7 +19,7 @@
 use rstd::prelude::*;
 
 use codec::{Decode, Encode, Codec, Input};
-use traits::{self, Member, DigestItem as DigestItemT, MaybeSerializeDebug};
+use traits::{self, Member, DigestItem as DigestItemT, MaybeSerializeDebug, MaybeHash};
 
 use substrate_primitives::hash::H512 as Signature;
 
@@ -124,7 +124,7 @@ impl<Hash, AuthorityId> DigestItem<Hash, AuthorityId> {
 
 impl<
 	Hash: Codec + Member + MaybeSerializeDebug,
-	AuthorityId: Codec + Member + MaybeSerializeDebug
+	AuthorityId: Codec + Member + MaybeSerializeDebug + MaybeHash
 > traits::DigestItem for DigestItem<Hash, AuthorityId> {
 	type Hash = Hash;
 	type AuthorityId = AuthorityId;
diff --git a/substrate/core/sr-primitives/src/testing.rs b/substrate/core/sr-primitives/src/testing.rs
index acbcd9241d..f552600de9 100644
--- a/substrate/core/sr-primitives/src/testing.rs
+++ b/substrate/core/sr-primitives/src/testing.rs
@@ -19,12 +19,30 @@
 use serde::{Serialize, Serializer, Deserialize, de::Error as DeError, Deserializer};
 use std::{fmt::Debug, ops::Deref, fmt};
 use codec::{Codec, Encode, Decode};
-use traits::{self, Checkable, Applyable, BlakeTwo256};
+use traits::{self, Checkable, Applyable, BlakeTwo256, Convert};
 use generic::DigestItem as GenDigestItem;
 
-pub use substrate_primitives::{H256, AuthorityId};
+pub use substrate_primitives::{H256, Ed25519AuthorityId};
+use substrate_primitives::U256;
 
-pub type DigestItem = GenDigestItem<H256, u64>;
+#[derive(Default, PartialEq, Eq, Clone, Decode, Encode, Debug)]
+#[cfg_attr(feature = "std", derive(Serialize, Deserialize))]
+pub struct UintAuthorityId(pub u64);
+impl Into<Ed25519AuthorityId> for UintAuthorityId {
+	fn into(self) -> Ed25519AuthorityId {
+		let bytes: [u8; 32] = U256::from(self.0).into();
+		Ed25519AuthorityId(bytes)
+	}
+}
+
+pub struct ConvertUintAuthorityId;
+impl Convert<u64, UintAuthorityId> for ConvertUintAuthorityId {
+	fn convert(a: u64) -> UintAuthorityId {
+		UintAuthorityId(a)
+	}
+}
+
+pub type DigestItem = GenDigestItem<H256, Ed25519AuthorityId>;
 
 #[derive(Default, PartialEq, Eq, Clone, Serialize, Debug, Encode, Decode)]
 pub struct Digest {
diff --git a/substrate/core/sr-primitives/src/traits.rs b/substrate/core/sr-primitives/src/traits.rs
index 8bdfd7eda6..0354953bfb 100644
--- a/substrate/core/sr-primitives/src/traits.rs
+++ b/substrate/core/sr-primitives/src/traits.rs
@@ -413,6 +413,16 @@ pub trait MaybeDisplay {}
 #[cfg(not(feature = "std"))]
 impl<T> MaybeDisplay for T {}
 
+#[cfg(feature = "std")]
+pub trait MaybeHash: ::rstd::hash::Hash {}
+#[cfg(feature = "std")]
+impl<T: ::rstd::hash::Hash> MaybeHash for T {}
+
+#[cfg(not(feature = "std"))]
+pub trait MaybeHash {}
+#[cfg(not(feature = "std"))]
+impl<T> MaybeHash for T {}
+
 #[cfg(feature = "std")]
 pub trait MaybeDecode: ::codec::Decode {}
 #[cfg(feature = "std")]
@@ -500,6 +510,8 @@ pub type NumberFor<B> = <<B as Block>::Header as Header>::Number;
 pub type DigestFor<B> = <<B as Block>::Header as Header>::Digest;
 /// Extract the digest item type for a block.
 pub type DigestItemFor<B> = <DigestFor<B> as Digest>::Item;
+/// Extract the authority ID type for a block.
+pub type AuthorityIdFor<B> = <DigestItemFor<B> as DigestItem>::AuthorityId;
 
 /// A "checkable" piece of information, used by the standard Substrate Executive in order to
 /// check the validity of a piece of extrinsic information, usually by verifying the signature.
@@ -575,7 +587,7 @@ pub trait Digest: Member + MaybeSerializeDebugButNotDeserialize + Default {
 /// If the runtime does not supports some 'system' items, use `()` as a stub.
 pub trait DigestItem: Codec + Member + MaybeSerializeDebugButNotDeserialize {
 	type Hash: Member + MaybeSerializeDebugButNotDeserialize;
-	type AuthorityId: Member + MaybeSerializeDebugButNotDeserialize;
+	type AuthorityId: Member + MaybeSerializeDebugButNotDeserialize + MaybeHash + codec::Encode + codec::Decode;
 
 	/// Returns Some if the entry is the `AuthoritiesChange` entry.
 	fn as_authorities_change(&self) -> Option<&[Self::AuthorityId]>;
diff --git a/substrate/core/test-runtime/src/genesismap.rs b/substrate/core/test-runtime/src/genesismap.rs
index 5e6adec86a..82e9423f05 100644
--- a/substrate/core/test-runtime/src/genesismap.rs
+++ b/substrate/core/test-runtime/src/genesismap.rs
@@ -19,23 +19,23 @@
 use std::collections::HashMap;
 use runtime_io::twox_128;
 use codec::{Encode, KeyedVec, Joiner};
-use primitives::{AuthorityId, ChangesTrieConfiguration};
+use primitives::{Ed25519AuthorityId, ChangesTrieConfiguration};
 use primitives::storage::well_known_keys;
 use runtime_primitives::traits::Block;
 
 /// Configuration of a general Substrate test genesis block.
 pub struct GenesisConfig {
 	pub changes_trie_config: Option<ChangesTrieConfiguration>,
-	pub authorities: Vec<AuthorityId>,
-	pub balances: Vec<(AuthorityId, u64)>,
+	pub authorities: Vec<Ed25519AuthorityId>,
+	pub balances: Vec<(Ed25519AuthorityId, u64)>,
 }
 
 impl GenesisConfig {
-	pub fn new_simple(authorities: Vec<AuthorityId>, balance: u64) -> Self {
+	pub fn new_simple(authorities: Vec<Ed25519AuthorityId>, balance: u64) -> Self {
 		Self::new(false, authorities, balance)
 	}
 
-	pub fn new(support_changes_trie: bool, authorities: Vec<AuthorityId>, balance: u64) -> Self {
+	pub fn new(support_changes_trie: bool, authorities: Vec<Ed25519AuthorityId>, balance: u64) -> Self {
 		GenesisConfig {
 			changes_trie_config: match support_changes_trie {
 				true => Some(super::changes_trie_config()),
diff --git a/substrate/core/test-runtime/src/lib.rs b/substrate/core/test-runtime/src/lib.rs
index cceeee74d1..8aafd99791 100644
--- a/substrate/core/test-runtime/src/lib.rs
+++ b/substrate/core/test-runtime/src/lib.rs
@@ -61,8 +61,7 @@ use runtime_primitives::{
 };
 use runtime_version::RuntimeVersion;
 pub use primitives::hash::H256;
-use primitives::AuthorityId;
-use primitives::OpaqueMetadata;
+use primitives::{Ed25519AuthorityId, OpaqueMetadata};
 #[cfg(any(feature = "std", test))]
 use runtime_version::NativeVersion;
 use consensus_aura::api as aura_api;
@@ -143,7 +142,7 @@ pub type BlockNumber = u64;
 /// Index of a transaction.
 pub type Index = u64;
 /// The item of a block digest.
-pub type DigestItem = runtime_primitives::generic::DigestItem<H256, u64>;
+pub type DigestItem = runtime_primitives::generic::DigestItem<H256, Ed25519AuthorityId>;
 /// The digest of a block.
 pub type Digest = runtime_primitives::generic::Digest<DigestItem>;
 /// A test block.
@@ -197,7 +196,7 @@ impl_runtime_apis! {
 			version()
 		}
 
-		fn authorities() -> Vec<AuthorityId> {
+		fn authorities() -> Vec<Ed25519AuthorityId> {
 			system::authorities()
 		}
 
diff --git a/substrate/core/test-runtime/src/system.rs b/substrate/core/test-runtime/src/system.rs
index 3703fb553e..81cbabe906 100644
--- a/substrate/core/test-runtime/src/system.rs
+++ b/substrate/core/test-runtime/src/system.rs
@@ -25,7 +25,7 @@ use runtime_primitives::generic;
 use runtime_primitives::{ApplyError, ApplyOutcome, ApplyResult, transaction_validity::TransactionValidity};
 use codec::{KeyedVec, Encode};
 use super::{AccountId, BlockNumber, Extrinsic, H256 as Hash, Block, Header, Digest};
-use primitives::{Blake2Hasher};
+use primitives::{Ed25519AuthorityId, Blake2Hasher};
 use primitives::storage::well_known_keys;
 
 const NONCE_OF: &[u8] = b"nonce:";
@@ -51,7 +51,7 @@ pub fn nonce_of(who: AccountId) -> u64 {
 }
 
 /// Get authorities ar given block.
-pub fn authorities() -> Vec<::primitives::AuthorityId> {
+pub fn authorities() -> Vec<Ed25519AuthorityId> {
 	let len: u32 = storage::unhashed::get(well_known_keys::AUTHORITY_COUNT)
 		.expect("There are always authorities in test-runtime");
 	(0..len)
@@ -94,7 +94,7 @@ pub fn execute_block(block: Block) {
 	// check digest
 	let mut digest = Digest::default();
 	if let Some(storage_changes_root) = storage_changes_root(header.parent_hash.into(), header.number - 1) {
-		digest.push(generic::DigestItem::ChangesTrieRoot::<Hash, u64>(storage_changes_root.into()));
+		digest.push(generic::DigestItem::ChangesTrieRoot(storage_changes_root.into()));
 	}
 	assert!(digest == header.digest, "Header digest items must match that calculated.");
 }
@@ -164,7 +164,7 @@ pub fn finalise_block() -> Header {
 
 	let mut digest = Digest::default();
 	if let Some(storage_changes_root) = storage_changes_root {
-		digest.push(generic::DigestItem::ChangesTrieRoot::<Hash, u64>(storage_changes_root));
+		digest.push(generic::DigestItem::ChangesTrieRoot(storage_changes_root));
 	}
 
 	Header {
diff --git a/substrate/node/cli/src/chain_spec.rs b/substrate/node/cli/src/chain_spec.rs
index 26e86f596b..b2d4b2ed4a 100644
--- a/substrate/node/cli/src/chain_spec.rs
+++ b/substrate/node/cli/src/chain_spec.rs
@@ -16,7 +16,7 @@
 
 //! Substrate chain configurations.
 
-use primitives::{AuthorityId, ed25519};
+use primitives::{Ed25519AuthorityId, ed25519};
 use node_primitives::AccountId;
 use node_runtime::{ConsensusConfig, CouncilSeatsConfig, CouncilVotingConfig, DemocracyConfig,
 	SessionConfig, StakingConfig, TimestampConfig, BalancesConfig, TreasuryConfig,
@@ -158,7 +158,7 @@ pub fn staging_testnet_config() -> ChainSpec {
 }
 
 /// Helper function to generate AuthorityID from seed
-pub fn get_authority_id_from_seed(seed: &str) -> AuthorityId {
+pub fn get_authority_id_from_seed(seed: &str) -> Ed25519AuthorityId {
 	let padded_seed = pad_seed(seed);
 	// NOTE from ed25519 impl:
 	// prefer pkcs#8 unless security doesn't matter -- this is used primarily for tests.
@@ -167,9 +167,9 @@ pub fn get_authority_id_from_seed(seed: &str) -> AuthorityId {
 
 /// Helper function to create GenesisConfig for testing
 pub fn testnet_genesis(
-	initial_authorities: Vec<AuthorityId>,
+	initial_authorities: Vec<Ed25519AuthorityId>,
 	upgrade_key: AccountId,
-	endowed_accounts: Option<Vec<AuthorityId>>,
+	endowed_accounts: Option<Vec<Ed25519AuthorityId>>,
 ) -> GenesisConfig {
 	let endowed_accounts = endowed_accounts.unwrap_or_else(|| {
 		vec![
diff --git a/substrate/node/primitives/src/lib.rs b/substrate/node/primitives/src/lib.rs
index e2336acafd..967b0d775c 100644
--- a/substrate/node/primitives/src/lib.rs
+++ b/substrate/node/primitives/src/lib.rs
@@ -56,7 +56,7 @@ pub type Balance = u128;
 
 /// The Ed25519 pub key of an session that belongs to an authority of the chain. This is
 /// exactly equivalent to what the substrate calls an "authority".
-pub type SessionKey = primitives::AuthorityId;
+pub type SessionKey = primitives::Ed25519AuthorityId;
 
 /// Index of a transaction in the chain.
 pub type Index = u64;
diff --git a/substrate/srml/aura/src/mock.rs b/substrate/srml/aura/src/mock.rs
index 125466c9c0..eb1fc9756b 100644
--- a/substrate/srml/aura/src/mock.rs
+++ b/substrate/srml/aura/src/mock.rs
@@ -18,7 +18,7 @@
 
 #![cfg(test)]
 
-use primitives::{BuildStorage, testing::{Digest, DigestItem, Header}};
+use primitives::{BuildStorage, testing::{Digest, DigestItem, Header, UintAuthorityId}};
 use runtime_io;
 use substrate_primitives::{H256, Blake2Hasher};
 use {Trait, Module, consensus, system, timestamp};
@@ -34,7 +34,7 @@ pub struct Test;
 impl consensus::Trait for Test {
 	const NOTE_OFFLINE_POSITION: u32 = 1;
 	type Log = DigestItem;
-	type SessionKey = u64;
+	type SessionKey = UintAuthorityId;
 	type InherentOfflineReport = ();
 }
 
@@ -66,7 +66,7 @@ pub fn new_test_ext(authorities: Vec<u64>) -> runtime_io::TestExternalities<Blak
 	let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
 	t.extend(consensus::GenesisConfig::<Test>{
 		code: vec![],
-		authorities,
+		authorities: authorities.into_iter().map(|a| UintAuthorityId(a)).collect(),
 	}.build_storage().unwrap().0);
 	t.extend(timestamp::GenesisConfig::<Test>{
 		period: 1,
diff --git a/substrate/srml/consensus/src/lib.rs b/substrate/srml/consensus/src/lib.rs
index 2c72642cf6..2a55ac9e19 100644
--- a/substrate/srml/consensus/src/lib.rs
+++ b/substrate/srml/consensus/src/lib.rs
@@ -143,12 +143,12 @@ impl<SessionKey: Member> RawLog<SessionKey> {
 
 // Implementation for tests outside of this crate.
 #[cfg(any(feature = "std", test))]
-impl<N> From<RawLog<N>> for primitives::testing::DigestItem where N: Into<u64> {
+impl<N> From<RawLog<N>> for primitives::testing::DigestItem where N: Into<substrate_primitives::Ed25519AuthorityId> {
 	fn from(log: RawLog<N>) -> primitives::testing::DigestItem {
 		match log {
 			RawLog::AuthoritiesChange(authorities) =>
-				primitives::generic::DigestItem::AuthoritiesChange
-					::<substrate_primitives::H256, u64>(authorities.into_iter()
+				primitives::generic::DigestItem::AuthoritiesChange(
+					authorities.into_iter()
 						.map(Into::into).collect()),
 		}
 	}
diff --git a/substrate/srml/consensus/src/mock.rs b/substrate/srml/consensus/src/mock.rs
index 5945a89018..78351309ac 100644
--- a/substrate/srml/consensus/src/mock.rs
+++ b/substrate/srml/consensus/src/mock.rs
@@ -18,7 +18,7 @@
 
 #![cfg(test)]
 
-use primitives::{BuildStorage, testing::{Digest, DigestItem, Header}};
+use primitives::{BuildStorage, testing::{Digest, DigestItem, Header, UintAuthorityId}};
 use runtime_io;
 use substrate_primitives::{H256, Blake2Hasher};
 use {GenesisConfig, Trait, Module, system};
@@ -33,7 +33,7 @@ pub struct Test;
 impl Trait for Test {
 	const NOTE_OFFLINE_POSITION: u32 = 1;
 	type Log = DigestItem;
-	type SessionKey = u64;
+	type SessionKey = UintAuthorityId;
 	type InherentOfflineReport = ::InstantFinalityReportVec<()>;
 }
 impl system::Trait for Test {
@@ -53,7 +53,7 @@ pub fn new_test_ext(authorities: Vec<u64>) -> runtime_io::TestExternalities<Blak
 	let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
 	t.extend(GenesisConfig::<Test>{
 		code: vec![],
-		authorities,
+		authorities: authorities.into_iter().map(|a| UintAuthorityId(a)).collect(),
 	}.build_storage().unwrap().0);
 	t.into()
 }
diff --git a/substrate/srml/consensus/src/tests.rs b/substrate/srml/consensus/src/tests.rs
index 9c57739fbc..9dc65136fb 100644
--- a/substrate/srml/consensus/src/tests.rs
+++ b/substrate/srml/consensus/src/tests.rs
@@ -18,21 +18,20 @@
 
 #![cfg(test)]
 
-use primitives::{generic, testing, traits::{OnFinalise, ProvideInherent}};
+use primitives::{generic, testing::{self, UintAuthorityId}, traits::{OnFinalise, ProvideInherent}};
 use runtime_io::with_externalities;
-use substrate_primitives::H256;
 use mock::{Consensus, System, new_test_ext};
 
 #[test]
 fn authorities_change_logged() {
 	with_externalities(&mut new_test_ext(vec![1, 2, 3]), || {
 		System::initialise(&1, &Default::default(), &Default::default());
-		Consensus::set_authorities(&[4, 5, 6]);
+		Consensus::set_authorities(&[UintAuthorityId(4), UintAuthorityId(5), UintAuthorityId(6)]);
 		Consensus::on_finalise(1);
 		let header = System::finalise();
 		assert_eq!(header.digest, testing::Digest {
 			logs: vec![
-				generic::DigestItem::AuthoritiesChange::<H256, u64>(vec![4, 5, 6]),
+				generic::DigestItem::AuthoritiesChange(vec![UintAuthorityId(4).into(), UintAuthorityId(5).into(), UintAuthorityId(6).into()]),
 			],
 		});
 	});
@@ -54,8 +53,8 @@ fn authorities_change_is_not_logged_when_not_changed() {
 fn authorities_change_is_not_logged_when_changed_back_to_original() {
 	with_externalities(&mut new_test_ext(vec![1, 2, 3]), || {
 		System::initialise(&1, &Default::default(), &Default::default());
-		Consensus::set_authorities(&[4, 5, 6]);
-		Consensus::set_authorities(&[1, 2, 3]);
+		Consensus::set_authorities(&[UintAuthorityId(4), UintAuthorityId(5), UintAuthorityId(6)]);
+		Consensus::set_authorities(&[UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
 		Consensus::on_finalise(1);
 		let header = System::finalise();
 		assert_eq!(header.digest, testing::Digest {
diff --git a/substrate/srml/grandpa/src/lib.rs b/substrate/srml/grandpa/src/lib.rs
index 50ab852891..1a0d0f7c31 100644
--- a/substrate/srml/grandpa/src/lib.rs
+++ b/substrate/srml/grandpa/src/lib.rs
@@ -61,7 +61,7 @@ use runtime_support::dispatch::Result;
 use runtime_support::storage::StorageValue;
 use runtime_support::storage::unhashed::StorageVec;
 use primitives::traits::{CurrentHeight, Convert};
-use substrate_primitives::AuthorityId;
+use substrate_primitives::Ed25519AuthorityId;
 use system::ensure_signed;
 use primitives::traits::MaybeSerializeDebug;
 
@@ -105,7 +105,7 @@ impl<N: Clone, SessionKey> RawLog<N, SessionKey> {
 }
 
 impl<N, SessionKey> GrandpaChangeSignal<N> for RawLog<N, SessionKey>
-	where N: Clone, SessionKey: Clone + Into<AuthorityId>,
+	where N: Clone, SessionKey: Clone + Into<Ed25519AuthorityId>,
 {
 	fn as_signal(&self) -> Option<ScheduledChange<N>> {
 		RawLog::as_signal(self).map(|(delay, next_authorities)| ScheduledChange {
@@ -243,7 +243,7 @@ impl<T: Trait> Module<T> {
 	}
 }
 
-impl<T: Trait> Module<T> where AuthorityId: core::convert::From<<T as Trait>::SessionKey> {
+impl<T: Trait> Module<T> where Ed25519AuthorityId: core::convert::From<<T as Trait>::SessionKey> {
 	/// See if the digest contains any scheduled change.
 	pub fn scrape_digest_change(log: &Log<T>)
 		-> Option<ScheduledChange<T::BlockNumber>>
diff --git a/substrate/srml/session/src/lib.rs b/substrate/srml/session/src/lib.rs
index 6992a5311f..05381e6df9 100644
--- a/substrate/srml/session/src/lib.rs
+++ b/substrate/srml/session/src/lib.rs
@@ -248,8 +248,8 @@ mod tests {
 	use runtime_io::with_externalities;
 	use substrate_primitives::{H256, Blake2Hasher};
 	use primitives::BuildStorage;
-	use primitives::traits::{Identity, BlakeTwo256};
-	use primitives::testing::{Digest, DigestItem, Header};
+	use primitives::traits::BlakeTwo256;
+	use primitives::testing::{Digest, DigestItem, Header, UintAuthorityId, ConvertUintAuthorityId};
 
 	impl_outer_origin!{
 		pub enum Origin for Test {}
@@ -260,7 +260,7 @@ mod tests {
 	impl consensus::Trait for Test {
 		const NOTE_OFFLINE_POSITION: u32 = 1;
 		type Log = DigestItem;
-		type SessionKey = u64;
+		type SessionKey = UintAuthorityId;
 		type InherentOfflineReport = ();
 	}
 	impl system::Trait for Test {
@@ -281,7 +281,7 @@ mod tests {
 		type OnTimestampSet = ();
 	}
 	impl Trait for Test {
-		type ConvertAccountIdToSessionKey = Identity;
+		type ConvertAccountIdToSessionKey = ConvertUintAuthorityId;
 		type OnSessionChange = ();
 		type Event = ();
 	}
@@ -294,7 +294,7 @@ mod tests {
 		let mut t = system::GenesisConfig::<Test>::default().build_storage().unwrap().0;
 		t.extend(consensus::GenesisConfig::<Test>{
 			code: vec![],
-			authorities: vec![1, 2, 3],
+			authorities: vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)],
 		}.build_storage().unwrap().0);
 		t.extend(timestamp::GenesisConfig::<Test>{
 			period: 5,
@@ -309,7 +309,7 @@ mod tests {
 	#[test]
 	fn simple_setup_should_work() {
 		with_externalities(&mut new_test_ext(), || {
-			assert_eq!(Consensus::authorities(), vec![1, 2, 3]);
+			assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1).into(), UintAuthorityId(2).into(), UintAuthorityId(3).into()]);
 			assert_eq!(Session::length(), 2);
 			assert_eq!(Session::validators(), vec![1, 2, 3]);
 		});
@@ -405,25 +405,25 @@ mod tests {
 			// Block 1: No change
 			System::set_block_number(1);
 			Session::check_rotate_session(1);
-			assert_eq!(Consensus::authorities(), vec![1, 2, 3]);
+			assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
 
 			// Block 2: Session rollover, but no change.
 			System::set_block_number(2);
 			Session::check_rotate_session(2);
-			assert_eq!(Consensus::authorities(), vec![1, 2, 3]);
+			assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
 
 			// Block 3: Set new key for validator 2; no visible change.
 			System::set_block_number(3);
-			assert_ok!(Session::set_key(Origin::signed(2), 5));
-			assert_eq!(Consensus::authorities(), vec![1, 2, 3]);
+			assert_ok!(Session::set_key(Origin::signed(2), UintAuthorityId(5)));
+			assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
 
 			Session::check_rotate_session(3);
-			assert_eq!(Consensus::authorities(), vec![1, 2, 3]);
+			assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(2), UintAuthorityId(3)]);
 
 			// Block 4: Session rollover, authority 2 changes.
 			System::set_block_number(4);
 			Session::check_rotate_session(4);
-			assert_eq!(Consensus::authorities(), vec![1, 5, 3]);
+			assert_eq!(Consensus::authorities(), vec![UintAuthorityId(1), UintAuthorityId(5), UintAuthorityId(3)]);
 		});
 	}
 }
diff --git a/substrate/srml/staking/src/mock.rs b/substrate/srml/staking/src/mock.rs
index cf5976f88a..b6efce154d 100644
--- a/substrate/srml/staking/src/mock.rs
+++ b/substrate/srml/staking/src/mock.rs
@@ -19,8 +19,8 @@
 #![cfg(test)]
 
 use primitives::BuildStorage;
-use primitives::{Perbill, traits::Identity};
-use primitives::testing::{Digest, DigestItem, Header};
+use primitives::Perbill;
+use primitives::testing::{Digest, DigestItem, Header, UintAuthorityId, ConvertUintAuthorityId};
 use substrate_primitives::{H256, Blake2Hasher};
 use runtime_io;
 use {GenesisConfig, Module, Trait, consensus, session, system, timestamp, balances};
@@ -35,7 +35,7 @@ pub struct Test;
 impl consensus::Trait for Test {
 	const NOTE_OFFLINE_POSITION: u32 = 1;
 	type Log = DigestItem;
-	type SessionKey = u64;
+	type SessionKey = UintAuthorityId;
 	type InherentOfflineReport = ();
 }
 impl system::Trait for Test {
@@ -58,7 +58,7 @@ impl balances::Trait for Test {
 	type Event = ();
 }
 impl session::Trait for Test {
-	type ConvertAccountIdToSessionKey = Identity;
+	type ConvertAccountIdToSessionKey = ConvertUintAuthorityId;
 	type OnSessionChange = Staking;
 	type Event = ();
 }
diff --git a/substrate/srml/system/src/lib.rs b/substrate/srml/system/src/lib.rs
index bd349982e4..67b10e2639 100644
--- a/substrate/srml/system/src/lib.rs
+++ b/substrate/srml/system/src/lib.rs
@@ -176,8 +176,7 @@ impl<Hash: Member> RawLog<Hash> {
 impl From<RawLog<substrate_primitives::H256>> for primitives::testing::DigestItem {
 	fn from(log: RawLog<substrate_primitives::H256>) -> primitives::testing::DigestItem {
 		match log {
-			RawLog::ChangesTrieRoot(root) => primitives::generic::DigestItem::ChangesTrieRoot
-				::<substrate_primitives::H256, u64>(root),
+			RawLog::ChangesTrieRoot(root) => primitives::generic::DigestItem::ChangesTrieRoot(root),
 		}
 	}
 }
diff --git a/substrate/srml/timestamp/src/lib.rs b/substrate/srml/timestamp/src/lib.rs
index d89bb50a64..0d9360b747 100644
--- a/substrate/srml/timestamp/src/lib.rs
+++ b/substrate/srml/timestamp/src/lib.rs
@@ -190,7 +190,7 @@ mod tests {
 	use substrate_primitives::H256;
 	use runtime_primitives::BuildStorage;
 	use runtime_primitives::traits::BlakeTwo256;
-	use runtime_primitives::testing::{Digest, DigestItem, Header};
+	use runtime_primitives::testing::{Digest, DigestItem, Header, UintAuthorityId};
 
 	impl_outer_origin! {
 		pub enum Origin for Test {}
@@ -213,7 +213,7 @@ mod tests {
 	impl consensus::Trait for Test {
 		const NOTE_OFFLINE_POSITION: u32 = 1;
 		type Log = DigestItem;
-		type SessionKey = u64;
+		type SessionKey = UintAuthorityId;
 		type InherentOfflineReport = ();
 	}
 	impl Trait for Test {