diff --git a/file_upload.go b/file_upload.go
index 14f7a58..de28bc0 100644
--- a/file_upload.go
+++ b/file_upload.go
@@ -8,6 +8,7 @@ import (
 	"crypto/sha256"
 	"encoding/base64"
 	"encoding/hex"
+	"fmt"
 	"io"
 	"mime"
 	"os"
@@ -74,10 +75,32 @@ func (protonDrive *ProtonDrive) handleRevisionConflict(ctx context.Context, link
 	}
 }
 
-func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, parentLink *proton.Link, filename string, modTime time.Time, mimeType string) (string, string, *crypto.SessionKey, *crypto.KeyRing, error) {
+type verificationData struct {
+	sessionKey       *crypto.SessionKey
+	verificationCode []byte
+}
+
+func (verifier *verificationData) verifyBlock(encData []byte) ([]byte, error) {
+	_, err := verifier.sessionKey.Decrypt(encData)
+	if err != nil {
+		return nil, fmt.Errorf("verification failed: %w", err)
+	}
+
+	result := make([]byte, len(verifier.verificationCode))
+	for i, verCodeByte := range verifier.verificationCode {
+		var encDataByte byte
+		if i < len(encData) {
+			encDataByte = encData[i]
+		}
+		result[i] = verCodeByte ^ encDataByte
+	}
+	return result, nil
+}
+
+func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, parentLink *proton.Link, filename string, modTime time.Time, mimeType string) (string, string, *crypto.SessionKey, *crypto.KeyRing, *verificationData, error) {
 	parentNodeKR, err := protonDrive.getLinkKR(ctx, parentLink)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	/*
@@ -86,7 +109,7 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 	*/
 	newNodeKey, newNodePassphraseEnc, newNodePassphraseSignature, err := generateNodeKeys(parentNodeKR, protonDrive.DefaultAddrKR)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	createFileReq := proton.CreateFileReq{
@@ -112,7 +135,7 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 	*/
 	err = createFileReq.SetName(filename, protonDrive.DefaultAddrKR, parentNodeKR)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	/*
@@ -121,17 +144,17 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 	*/
 	signatureVerificationKR, err := protonDrive.getSignatureVerificationKeyring([]string{parentLink.SignatureEmail}, parentNodeKR)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 	parentHashKey, err := parentLink.GetHashKey(parentNodeKR, signatureVerificationKR)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	/* Use parent's hash key */
 	err = createFileReq.SetHash(filename, parentHashKey)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	/*
@@ -140,7 +163,7 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 	*/
 	newNodeKR, err := getKeyRing(parentNodeKR, protonDrive.DefaultAddrKR, newNodeKey, newNodePassphraseEnc, newNodePassphraseSignature)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	/*
@@ -149,7 +172,7 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 	*/
 	newSessionKey, err := createFileReq.SetContentKeyPacketAndSignature(newNodeKR)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	createFileAction := func() (*proton.CreateFileRes, *proton.Link, error) {
@@ -190,12 +213,12 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 
 	createFileResp, link, err := createFileAction()
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	revisionID, shouldSubmitCreateFileRequestAgain, err := protonDrive.handleRevisionConflict(ctx, link, createFileResp)
 	if err != nil {
-		return "", "", nil, nil, err
+		return "", "", nil, nil, nil, err
 	}
 
 	if shouldSubmitCreateFileRequestAgain {
@@ -203,12 +226,12 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 		// we need to delete the link and recreate one
 		createFileResp, link, err = createFileAction()
 		if err != nil {
-			return "", "", nil, nil, err
+			return "", "", nil, nil, nil, err
 		}
 
 		revisionID, _, err = protonDrive.handleRevisionConflict(ctx, link, createFileResp)
 		if err != nil {
-			return "", "", nil, nil, err
+			return "", "", nil, nil, nil, err
 		}
 	}
 
@@ -219,34 +242,54 @@ func (protonDrive *ProtonDrive) createFileUploadDraft(ctx context.Context, paren
 		// get original sessionKey and nodeKR for the current link
 		parentNodeKR, err = protonDrive.getLinkKRByID(ctx, link.ParentLinkID)
 		if err != nil {
-			return "", "", nil, nil, err
+			return "", "", nil, nil, nil, err
 		}
 		signatureVerificationKR, err := protonDrive.getSignatureVerificationKeyring([]string{link.SignatureEmail})
 		if err != nil {
-			return "", "", nil, nil, err
+			return "", "", nil, nil, nil, err
 		}
 		newNodeKR, err = link.GetKeyRing(parentNodeKR, signatureVerificationKR)
 		if err != nil {
-			return "", "", nil, nil, err
+			return "", "", nil, nil, nil, err
 		}
 		newSessionKey, err = link.GetSessionKey(newNodeKR)
 		if err != nil {
-			return "", "", nil, nil, err
+			return "", "", nil, nil, nil, err
 		}
 	} else {
 		linkID = createFileResp.ID
 	}
 
-	return linkID, revisionID, newSessionKey, newNodeKR, nil
+	verification, err := protonDrive.c.VerifyRevision(ctx, protonDrive.MainShare.ShareID, linkID, revisionID)
+	if err != nil {
+		return "", "", nil, nil, nil, err
+	}
+	encSessionKey, err := base64.StdEncoding.DecodeString(verification.ContentKeyPacket)
+	if err != nil {
+		return "", "", nil, nil, nil, err
+	}
+	verifierSessionKey, err := newNodeKR.DecryptSessionKey(encSessionKey)
+	if err != nil {
+		return "", "", nil, nil, nil, err
+	}
+	verificationCode, err := base64.StdEncoding.DecodeString(verification.VerificationCode)
+	if err != nil {
+		return "", "", nil, nil, nil, err
+	}
+
+	return linkID, revisionID, newSessionKey, newNodeKR, &verificationData{
+		sessionKey:       verifierSessionKey,
+		verificationCode: verificationCode,
+	}, nil
 }
 
-func (protonDrive *ProtonDrive) uploadAndCollectBlockData(ctx context.Context, newSessionKey *crypto.SessionKey, newNodeKR *crypto.KeyRing, file io.Reader, linkID, revisionID string) ([]byte, int64, []int64, string, error) {
+func (protonDrive *ProtonDrive) uploadAndCollectBlockData(ctx context.Context, newSessionKey *crypto.SessionKey, verifier *verificationData, newNodeKR *crypto.KeyRing, file io.Reader, linkID, revisionID string) ([]byte, int64, []int64, string, error) {
 	type PendingUploadBlocks struct {
 		blockUploadInfo proton.BlockUploadInfo
 		encData         []byte
 	}
 
-	if newSessionKey == nil || newNodeKR == nil {
+	if newSessionKey == nil || newNodeKR == nil || verifier == nil {
 		return nil, 0, nil, "", ErrMissingInputUploadAndCollectBlockData
 	}
 
@@ -360,10 +403,13 @@ func (protonDrive *ProtonDrive) uploadAndCollectBlockData(ctx context.Context, n
 		h.Write(encData)
 		hash := h.Sum(nil)
 		base64Hash := base64.StdEncoding.EncodeToString(hash)
+		manifestSignatureData = append(manifestSignatureData, hash...)
+
+		verificationToken, err := verifier.verifyBlock(encData)
 		if err != nil {
 			return nil, 0, nil, "", err
 		}
-		manifestSignatureData = append(manifestSignatureData, hash...)
+		verificationTokenBase64 := base64.StdEncoding.EncodeToString(verificationToken)
 
 		pendingUploadBlocks = append(pendingUploadBlocks, PendingUploadBlocks{
 			blockUploadInfo: proton.BlockUploadInfo{
@@ -371,6 +417,9 @@ func (protonDrive *ProtonDrive) uploadAndCollectBlockData(ctx context.Context, n
 				Size:         int64(len(encData)),
 				EncSignature: encSignatureStr,
 				Hash:         base64Hash,
+				Verifier: proton.BlockUploadInfoVerifier{
+					Token: verificationTokenBase64,
+				},
 			},
 			encData: encData,
 		})
@@ -432,7 +481,7 @@ func (protonDrive *ProtonDrive) uploadFile(ctx context.Context, parentLink *prot
 	}
 
 	/* step 1: create a draft */
-	linkID, revisionID, newSessionKey, newNodeKR, err := protonDrive.createFileUploadDraft(ctx, parentLink, filename, modTime, mimeType)
+	linkID, revisionID, newSessionKey, newNodeKR, verifier, err := protonDrive.createFileUploadDraft(ctx, parentLink, filename, modTime, mimeType)
 	if err != nil {
 		return "", nil, err
 	}
@@ -442,7 +491,7 @@ func (protonDrive *ProtonDrive) uploadFile(ctx context.Context, parentLink *prot
 	}
 
 	/* step 2: upload blocks and collect block data */
-	manifestSignature, fileSize, blockSizes, digests, err := protonDrive.uploadAndCollectBlockData(ctx, newSessionKey, newNodeKR, file, linkID, revisionID)
+	manifestSignature, fileSize, blockSizes, digests, err := protonDrive.uploadAndCollectBlockData(ctx, newSessionKey, verifier, newNodeKR, file, linkID, revisionID)
 	if err != nil {
 		return "", nil, err
 	}