Elizabeth/aura (#18)

* added bootnodes to bootnodes.go and added authorities array to GoerliChainConfig in params/config.go

* Seal() returns errUnauthorized if not authorized to sign block

* verifySeal now checks if signer of block was correct signer at that turn

consensus/aura/aura.go

@@ -454,27 +454,35 @@ func (a *Aura) verifySeal(chain consensus.ChainReader, header *types.Header, par
 		return errUnknownBlock
 	}
 	// Retrieve the snapshot needed to verify this header and cache it
-	snap, err := a.snapshot(chain, number-1, header.ParentHash, parents)
-	if err != nil {
-		return err
-	}
+	// snap, err := a.snapshot(chain, number-1, header.ParentHash, parents)
+	// if err != nil {
+	// 	return err
+	// }
 
 	// Resolve the authorization key and check against signers
 	signer, err := ecrecover(header, a.signatures)
 	if err != nil {
 		return err
 	}
-	if _, ok := snap.Signers[signer]; !ok {
+
+	ts := header.Time.Uint64()
+	step := ts % a.config.Period
+	turn := step % uint64(len(a.config.Authorities))
+	if signer != a.config.Authorities[turn] {
+		// not authorized to sign
 		return errUnauthorized
 	}
-	for seen, recent := range snap.Recents {
-		if recent == signer {
-			// Signer is among recents, only fail if the current block doesn't shift it out
-			if limit := uint64(len(snap.Signers)/2 + 1); seen > number-limit {
-				return errUnauthorized
-			}
-		}
-	}
+	// if _, ok := snap.Signers[signer]; !ok {
+	// 	return errUnauthorized
+	// }
+	// for seen, recent := range snap.Recents {
+	// 	if recent == signer {
+	// 		// Signer is among recents, only fail if the current block doesn't shift it out
+	// 		if limit := uint64(len(snap.Signers)/2 + 1); seen > number-limit {
+	// 			return errUnauthorized
+	// 		}
+	// 	}
+	// }
 	// Ensure that the difficulty corresponds to the turn-ness of the signer
 	//inturn := snap.inturn(header.Number.Uint64(), signer)
 	//if inturn && header.Difficulty.Cmp(diffInTurn) != 0 {
@@ -591,24 +599,34 @@ func (a *Aura) Seal(chain consensus.ChainReader, block *types.Block, results cha
 	signer, signFn := a.signer, a.signFn
 	a.lock.RUnlock()
 
-	// Bail out if we're unauthorized to sign a block
-	snap, err := a.snapshot(chain, number-1, header.ParentHash, nil)
-	if err != nil {
-		return err
-	}
-	if _, authorized := snap.Signers[signer]; !authorized {
+
+	// check if authorized to sign
+	step := uint64(time.Now().Unix()) % a.config.Period
+	turn := step % uint64(len(a.config.Authorities))
+	if a.signer != a.config.Authorities[turn] {
+		// not authorized to sign
 		return errUnauthorized
 	}
-	// If we're amongst the recent signers, wait for the next block
-	for seen, recent := range snap.Recents {
-		if recent == signer {
-			// Signer is among recents, only wait if the current block doesn't shift it out
-			if limit := uint64(len(snap.Signers)/2 + 1); number < limit || seen > number-limit {
-				log.Info("Signed recently, must wait for others")
-				return nil
-			}
-		}
-	}
+
+	// Bail out if we're unauthorized to sign a block
+	// snap, err := a.snapshot(chain, number-1, header.ParentHash, nil)
+	// if err != nil {
+	// 	return err
+	// }
+	// if _, authorized := snap.Signers[signer]; !authorized {
+	// 	return errUnauthorized
+	// }
+	// // If we're amongst the recent signers, wait for the next block
+	// for seen, recent := range snap.Recents {
+	// 	if recent == signer {
+	// 		// Signer is among recents, only wait if the current block doesn't shift it out
+	// 		if limit := uint64(len(snap.Signers)/2 + 1); number < limit || seen > number-limit {
+	// 			log.Info("Signed recently, must wait for others")
+	// 			return nil
+	// 		}
+	// 	}
+	// }
+
 	// Sweet, the protocol permits us to sign the block, wait for our time
 	delay := time.Unix(header.Time.Int64(), 0).Sub(time.Now()) // nolint: gosimple
 	//if header.Difficulty.Cmp(diffNoTurn) == 0 {

params/config.go

@@ -92,10 +92,10 @@ var (
 		ByzantiumBlock:      big.NewInt(0),
 		ConstantinopleBlock: nil,
 		Aura: &AuraConfig{
-			Period: 15,
+			Period: 4,
 			Epoch:  30000,
-			Authorities: []string{
-				"0x540a9fe3d2381016dec8ffba7235c6fb00b0f942",
+			Authorities: []common.Address{
+				common.HexToAddress("0x540a9fe3d2381016dec8ffba7235c6fb00b0f942"),
 			},
 			Difficulty:  big.NewInt(131072),
 		},
@@ -166,7 +166,7 @@ type CliqueConfig struct {
 type AuraConfig struct {
 	Period uint64 `json:"period"` // Number of seconds between blocks to enforce
 	Epoch  uint64 `json:"epoch"`  // Epoch length to reset votes and checkpoint
-	Authorities []string `json:"authorities"` // list of addresses of authorities
+	Authorities []common.Address `json:"authorities"` // list of addresses of authorities
 	Difficulty *big.Int `json:"difficulty"` // Constant block difficulty
 }