diff --git a/internal/block/header.go b/internal/block/header.go
index ca7cea04..15b49f0a 100644
--- a/internal/block/header.go
+++ b/internal/block/header.go
@@ -5,16 +5,23 @@ import (
 	"github.com/eigerco/strawberry/internal/time"
 )
 
+const NumberOfValidators uint16 = 1023
+
 // Header as defined in the section 5 in the paper
 type Header struct {
 	ParentHash           crypto.Hash                     // Hp
 	PriorStateRoot       crypto.Hash                     // Hr
 	ExtrinsicHash        crypto.Hash                     // Hx
 	TimeSlotIndex        time.Timeslot                   // Ht
-	EpochMarker          []crypto.Hash                   // He
+	EpochMarker          *Epoch                          // He
 	WinningTicketsMarker [time.TimeslotsPerEpoch]*Ticket // Hw
 	JudgementsMarkers    []crypto.Hash                   // Hj
-	BlockAuthorKey       []byte                          // Hk
-	VRFSignature         []byte                          // Hv
-	BlockSealSignature   []byte                          // Hs
+	PublicKeyIndex       uint16                          // Hk
+	VRFSignature         crypto.BandersnatchSignature    // Hv
+	BlockSealSignature   crypto.BandersnatchSignature    // Hs
+}
+
+type Epoch struct {
+	Keys    [NumberOfValidators]crypto.BandersnatchPublicKey
+	Entropy crypto.Hash
 }
diff --git a/internal/crypto/bandersnatch.go b/internal/crypto/bandersnatch.go
new file mode 100644
index 00000000..b70e5dbf
--- /dev/null
+++ b/internal/crypto/bandersnatch.go
@@ -0,0 +1,4 @@
+package crypto
+
+type BandersnatchPublicKey [BandersnatchSize]byte
+type BandersnatchSignature [96]byte