state proofs: add block hash to LightBlockHeader

config/consensus.go

@@ -419,6 +419,11 @@
 	// their account balances.
 	StateProofExcludeTotalWeightWithRewards bool
 
+	// StateProofBlockHashInLightHeader specifies that the LightBlockHeader
+	// committed to by state proofs should contain the BlockHash of each
+	// block, instead of the seed.
+	StateProofBlockHashInLightHeader bool
+
 	// EnableAssetCloseAmount adds an extra field to the ApplyData. The field contains the amount of the remaining
 	// asset that were sent to the close-to address.
 	EnableAssetCloseAmount bool
@@ -759,15 +764,20 @@
 		return err
 	}
 	if newConsensus != nil {
-		Consensus = newConsensus
-		// Set allocation limits
-		for _, p := range Consensus {
-			checkSetAllocBounds(p)
-		}
+		SetConfigurableConsensusProtocols(newConsensus)
 	}
 	return nil
 }
 
+// SetConfigurableConsensusProtocols sets the configurable protocols.
+func SetConfigurableConsensusProtocols(newConsensus ConsensusProtocols) {
+	Consensus = newConsensus
+	// Set allocation limits
+	for _, p := range Consensus {
+		checkSetAllocBounds(p)
+	}
+}
+
 // PreloadConfigurableConsensusProtocols loads the configurable protocols from the data directory
 // and merge it with a copy of the Consensus map. Then, it returns it to the caller.
 func PreloadConfigurableConsensusProtocols(dataDirectory string) (ConsensusProtocols, error) {
@@ -1377,6 +1387,8 @@
 	vFuture.LogicSigVersion = 10 // When moving this to a release, put a new higher LogicSigVersion here
 	vFuture.EnableLogicSigCostPooling = true
 
+	vFuture.StateProofBlockHashInLightHeader = true
+
 	// Setting DynamicFilterTimeout in vFuture will impact e2e test performance
 	// by reducing round time. Hence, it is commented out for now.
 	// vFuture.DynamicFilterTimeout = true

data/bookkeeping/lightBlockHeader.go

@@ -17,6 +17,7 @@
 package bookkeeping
 
 import (
+	"github.com/algorand/go-algorand/config"
 	"github.com/algorand/go-algorand/crypto"
 	"github.com/algorand/go-algorand/data/basics"
 	"github.com/algorand/go-algorand/data/committee"
@@ -38,21 +39,36 @@
 		In addition, we make sure that the Seed (The unpredictable value) would be the first field that gets
 		hashed (give it the lowest codec value in the LightBlockHeader struct) to mitigate a collision attack
 		on the merkle damgard construction.
+
+		The BlockHash serves a similar role, in that it also depends on the seed and introduces some
+		uncontrollable input.  It is slightly weaker, in the sense that an adversary can influence
+		the BlockHash to some degree (e.g., by including specific transactions in the payset), but
+		it comes with the added benefit of allowing to authenticate the entire blockchain based on
+		the BlockHash value.
 	*/
 	Seed                committee.Seed       `codec:"0"`
+	BlockHash           BlockHash            `codec:"1"`
 	Round               basics.Round         `codec:"r"`
 	GenesisHash         crypto.Digest        `codec:"gh"`
 	Sha256TxnCommitment crypto.GenericDigest `codec:"tc,allocbound=crypto.Sha256Size"`
 }
 
 // ToLightBlockHeader creates returns a LightBlockHeader from a given block header
 func (bh *BlockHeader) ToLightBlockHeader() LightBlockHeader {
-	return LightBlockHeader{
-		Seed:                bh.Seed,
+	res := LightBlockHeader{
 		GenesisHash:         bh.GenesisHash,
 		Round:               bh.Round,
 		Sha256TxnCommitment: bh.Sha256Commitment[:],
 	}
+
+	proto := config.Consensus[bh.CurrentProtocol]
+	if proto.StateProofBlockHashInLightHeader {
+		res.BlockHash = bh.Hash()
+	} else {
+		res.Seed = bh.Seed
+	}
+
+	return res
 }
 
 // ToBeHashed implements the crypto.Hashable interface

test/e2e-go/features/stateproofs/stateproofs_test.go

@@ -323,6 +323,7 @@ func TestStateProofMessageCommitmentVerification(t *testing.T) {
 	consensusVersion := protocol.ConsensusVersion("test-fast-stateproofs")
 	consensusParams := getDefaultStateProofConsensusParams()
 	configurableConsensus[consensusVersion] = consensusParams
+	config.SetConfigurableConsensusProtocols(configurableConsensus)
 
 	var fixture fixtures.RestClientFixture
 	fixture.SetConsensus(configurableConsensus)