Add randomness contract support to AuthorityRound. (#10946)

* Add randomness contract support to Authority Round.

Changes have been cherry-picked from poanetwork's aura-pos branch.
Most of the work has been done by @mbr.

* Address review comments for randomness contract.

Co-Authored-By: David <dvdplm@gmail.com>

* Rename revealSecret to revealNumber

* Update Randomness contract bytecode

* Use H256, rename secret to random number.

* Use get_commit_and_cipher

* Clean up Miner::prepare_block.

* Remove is_reveal_phase call.

* Add more comments, require randomness contract map.

* Simplify run_randomness_phase

* Address review comments.

* Remove Client::transact_contract.

ethcore/engine/src/engine.rs

@@ -32,7 +32,7 @@ use common_types::{
 	},
 	errors::{EthcoreError as Error, EngineError},
 	snapshot::Snapshotting,
-	transaction::{self, UnverifiedTransaction},
+	transaction::{self, SignedTransaction, UnverifiedTransaction},
 };
 use client_traits::EngineClient;
 
@@ -185,6 +185,14 @@ pub trait Engine: Sync + Send {
 	/// Allow mutating the header during seal generation. Currently only used by Clique.
 	fn on_seal_block(&self, _block: &mut ExecutedBlock) -> Result<(), Error> { Ok(()) }
 
+	/// Returns a list of transactions for a new block if we are the author.
+	///
+	/// This is called when the miner prepares a new block that this node will author and seal. It returns a list of
+	/// transactions that will be added to the block before any other transactions from the queue.
+	fn generate_engine_transactions(&self, _block: &ExecutedBlock) -> Result<Vec<SignedTransaction>, Error> {
+		Ok(Vec::new())
+	}
+
 	/// Returns the engine's current sealing state.
 	fn sealing_state(&self) -> SealingState { SealingState::External }
 

ethcore/engine/src/signer.rs

@@ -17,7 +17,7 @@
 //! A signer used by Engines which need to sign messages.
 
 use ethereum_types::{H256, Address};
-use parity_crypto::publickey::{Signature, KeyPair, Error};
+use parity_crypto::publickey::{ecies, Public, Signature, KeyPair, Error};
 
 /// Everything that an Engine needs to sign messages.
 pub trait EngineSigner: Send + Sync {
@@ -26,6 +26,12 @@ pub trait EngineSigner: Send + Sync {
 
 	/// Signing address
 	fn address(&self) -> Address;
+
+	/// Decrypt a message that was encrypted to this signer's key.
+	fn decrypt(&self, auth_data: &[u8], cipher: &[u8]) -> Result<Vec<u8>, Error>;
+
+	/// The signer's public key, if available.
+	fn public(&self) -> Option<Public>;
 }
 
 /// Creates a new `EngineSigner` from given key pair.
@@ -40,7 +46,15 @@ impl EngineSigner for Signer {
 		parity_crypto::publickey::sign(self.0.secret(), &hash)
 	}
 
+	fn decrypt(&self, auth_data: &[u8], cipher: &[u8]) -> Result<Vec<u8>, Error> {
+		ecies::decrypt(self.0.secret(), auth_data, cipher)
+	}
+
 	fn address(&self) -> Address {
 		self.0.address()
 	}
+
+	fn public(&self) -> Option<Public> {
+		Some(*self.0.public())
+	}
 }

ethcore/engine/src/test_helpers.rs

@@ -20,7 +20,7 @@ use std::sync::Arc;
 
 use ethereum_types::{Address, H256};
 use ethkey::Password;
-use parity_crypto::publickey::{Signature, Error};
+use parity_crypto::publickey::{Public, Signature, Error};
 use log::warn;
 use accounts::{self, AccountProvider, SignError};
 
@@ -44,7 +44,18 @@ impl EngineSigner for (Arc<AccountProvider>, Address, Password) {
 		}
 	}
 
+	fn decrypt(&self, auth_data: &[u8], cipher: &[u8]) -> Result<Vec<u8>, Error> {
+		self.0.decrypt(self.1, None, auth_data, cipher).map_err(|e| {
+			warn!("Unable to decrypt message: {:?}", e);
+			Error::InvalidMessage
+		})
+	}
+
 	fn address(&self) -> Address {
 		self.1
 	}
+
+	fn public(&self) -> Option<Public> {
+		self.0.account_public(self.1, &self.2).ok()
+	}
 }