Verification by root and not by slot

cl/cltypes/Makefile

@@ -1,5 +1,5 @@
 all:
-	go run github.com/ferranbt/fastssz/sszgen -path types.go 
-	go run github.com/ferranbt/fastssz/sszgen -path network.go 	
+	go run github.com/prysmaticlabs/fastssz/sszgen -path types.go 
+	go run github.com/prysmaticlabs/fastssz/sszgen -path network.go 	
 clean:
 	rm lightrpc/*.pb.go

cl/cltypes/custom_types.go

@@ -1,8 +1,8 @@
 package cltypes
 
 import (
-	ssz "github.com/ferranbt/fastssz"
 	"github.com/pkg/errors"
+	ssz "github.com/prysmaticlabs/fastssz"
 )
 
 const (

cl/cltypes/types.go

@@ -299,12 +299,12 @@ type Checkpoint struct {
  */
 type AggregateAndProof struct {
 	AggregatorIndex uint64
-	Aggregate       Attestation
+	Aggregate       *Attestation
 	SelectionProof  [96]byte `ssz-size:"96"`
 }
 
 type SignedAggregateAndProof struct {
-	Message   AggregateAndProof
+	Message   *AggregateAndProof
 	Signature [96]byte `ssz-size:"96"`
 }
 
@@ -338,6 +338,23 @@ type BeaconState struct {
 	LatestExecutionPayloadHeader *ExecutionHeader
 }
 
+// BlockRoot retrieves a the state block root from the state.
+func (b *BeaconState) BlockRoot() ([32]byte, error) {
+	stateRoot, err := b.HashTreeRoot()
+	if err != nil {
+		return [32]byte{}, nil
+	}
+	// We make a temporary header for block root computation
+	tempHeader := &BeaconBlockHeader{
+		Slot:          b.LatestBlockHeader.Slot,
+		ProposerIndex: b.LatestBlockHeader.ProposerIndex,
+		ParentRoot:    b.LatestBlockHeader.ParentRoot,
+		BodyRoot:      b.LatestBlockHeader.BodyRoot,
+		Root:          stateRoot,
+	}
+	return tempHeader.HashTreeRoot()
+}
+
 type ObjectSSZ interface {
 	ssz.Marshaler
 	ssz.Unmarshaler