From 74c46bbce2972a0bd82657c49f1b3a4280922271 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=BDiga=20Kokelj?= <ziga.kokelj@gmail.com>
Date: Fri, 17 Jan 2025 14:39:09 +0100
Subject: [PATCH] add data to composite hash & sign it

---
 go/enclave/nodetype/sequencer.go | 29 +++++++++++++++++++++++++----
 go/ethadapter/blob.go            |  6 +++++-
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/go/enclave/nodetype/sequencer.go b/go/enclave/nodetype/sequencer.go
index 24ba59b50..b7b38cbce 100644
--- a/go/enclave/nodetype/sequencer.go
+++ b/go/enclave/nodetype/sequencer.go
@@ -328,13 +328,34 @@ func (s *sequencer) CreateRollup(ctx context.Context, lastBatchNo uint64) (*comm
 		return nil, fmt.Errorf("failed to encode rollup to blobs: %w", err)
 	}
 
-	// Store the blob data
+	// Calculate blob hash
+	blobHash, err := ethadapter.ComputeBlobHash(blobs[0])
+	if err != nil {
+		return nil, fmt.Errorf("failed to compute blob hash: %w", err)
+	}
+
+	// Store blob data and required fields
 	extRollup.BlobData = blobs
+	extRollup.Header.BlobHash = blobHash
+	extRollup.Header.MessageRoot = gethcommon.Hash{} // TODO: Implement message root
+	extRollup.Header.BlockNumber = currentL1Head.Number.Uint64()
+	extRollup.Header.CompressionL1Head = currentL1Head.Hash()
+
+	// Create composite hash matching the contract expectation
+	compositeHash := gethcrypto.Keccak256Hash(
+		blobHash.Bytes(),
+		extRollup.Header.MessageRoot.Bytes(),
+		currentL1Head.Hash().Bytes(),
+		big.NewInt(int64(currentL1Head.Number.Uint64())).Bytes(),
+		big.NewInt(int64(extRollup.Header.LastBatchSeqNo)).Bytes(),
+	)
 
-	// Sign the rollup
-	if err := s.signRollup(extRollup); err != nil {
-		return nil, fmt.Errorf("failed to sign created rollup: %w", err)
+	// Sign the composite hash
+	signature, err := s.enclaveKeyService.Sign(compositeHash)
+	if err != nil {
+		return nil, fmt.Errorf("failed to sign rollup: %w", err)
 	}
+	extRollup.Header.Signature = signature
 
 	return extRollup, nil
 }
diff --git a/go/ethadapter/blob.go b/go/ethadapter/blob.go
index b27d9a914..886b20e9a 100644
--- a/go/ethadapter/blob.go
+++ b/go/ethadapter/blob.go
@@ -162,5 +162,9 @@ func ComputeBlobHash(blob *kzg4844.Blob) (gethcommon.Hash, error) {
 		return gethcommon.Hash{}, err
 	}
 
-	return KZGToVersionedHash(commitment), nil
+	// Create versioned hash matching EIP-4844 specification
+	var hash gethcommon.Hash
+	hash[0] = 0x01 // Version byte
+	copy(hash[1:], commitment[:])
+	return hash, nil
 }