if err != nil {
		writeErrorResponse(ctx, w, toAPIError(ctx, err), r.URL)
		return
	}

	if isEncrypted {
		sseS3 := crypto.S3.IsRequested(r.Header) || crypto.S3.IsEncrypted(mi.UserDefined)
		partInfo.ETag = tryDecryptETag(objectEncryptionKey[:], partInfo.ETag, sseS3)
	}

	response := generateCopyObjectPartResponse(partInfo.ETag, partInfo.LastModified)
	encodedSuccessResponse := encodeResponse(response)

	sseC := crypto.SSEC.IsRequested(r.Header)
	sseS3 := crypto.S3.IsRequested(r.Header)
	sseKMS := crypto.S3KMS.IsRequested(r.Header)

	isSourceEncrypted := sseCopyC || sseCopyS3 || sseCopyKMS
	isTargetEncrypted := sseC || sseS3 || sseKMS

	if sseC {
		newKey, err = ParseSSECustomerRequest(r)
		if err != nil {