fixup event helpers

logverification/eventhelpers.go

@@ -1,70 +1,19 @@
 package logverification
 
 import (
-	"crypto/sha256"
-	"encoding/binary"
 	"encoding/json"
-	"errors"
 	"sort"
 
 	"github.com/datatrails/go-datatrails-common-api-gen/assets/v2/assets"
-	"github.com/datatrails/go-datatrails-merklelog/massifs"
-	"github.com/datatrails/go-datatrails-simplehash/simplehash"
 	"google.golang.org/protobuf/encoding/protojson"
 )
 
 // EventDetails contains key information for verifying inclusion of merkle log events
 type EventDetails struct {
-	eventID     string
-	tenantID    string
-	eventHash   []byte
-	merkleLog   *assets.MerkleLogEntry
-	massifIndex uint64
-}
-
-// HashEvent creates a hash of the supplied event in the canonical V3 format.
-func HashEvent(idBytes []byte, err error, v3event simplehash.V3Event) ([]byte, error) {
-	hasher := sha256.New()
-
-	domainSeparator := []byte{byte(LeafTypePlain)}
-	hasher.Write(domainSeparator)
-
-	hasher.Write(idBytes)
-
-	err = simplehash.V3HashEvent(hasher, v3event)
-	if err != nil {
-		return nil, err
-	}
-
-	hash := hasher.Sum(nil)
-
-	return hash, nil
-}
-
-// getIdTimestamp retrieves the ID Timestamp from a wrapped event
-func getIdTimestamp(timestamp string) ([]byte, error) {
-
-	// Note that we store the idtimestamp in the event data with the epoch
-	// prefixed to it. So that no matter when the event data is examined, that
-	// information is available. We do NOT include the epoch in the hash because
-	// we will never alow a single log to span multiple epochs. We will just
-	// start a new log. And we preserve the unified history provability by
-	// puting a commitment to the final state of the previous log as the first
-	// entry in the new log.
-
-	id, epoch, err := massifs.SplitIDTimestampHex(timestamp)
-	if err != nil {
-		return nil, err
-	}
-	if epoch < 1 {
-		return nil, errors.New("epoch is before datatrails existed")
-	}
-	if epoch > 1 {
-		return nil, errors.New("epoch is after Jan 2038")
-	}
-	b := make([]byte, 8)
-	binary.BigEndian.PutUint64(b, id)
-	return b, nil
+	eventID   string
+	tenantID  string
+	eventHash []byte
+	merkleLog *assets.MerkleLogEntry
 }
 
 // ParseEventList takes a json list of events returned by the datatrails events API
@@ -108,18 +57,8 @@ func ParseEventList(eventsJson []byte) ([]EventDetails, error) {
 			return nil, err
 		}
 
-		// Hash the events we want to verify using the v3 schema
-		v3event, err := simplehash.V3FromEventJSON(eventJson)
-		if err != nil {
-			return nil, err
-		}
-
-		idBytes, err := getIdTimestamp(merkleLog.Commit.Idtimestamp)
-		if err != nil {
-			return nil, err
-		}
-
-		eventHash, err := HashEvent(idBytes, err, v3event)
+		hasher := LogVersion0Hasher{}
+		eventHash, err := hasher.HashEvent(eventJson)
 		if err != nil {
 			return nil, err
 		}