diff --git a/README.md b/README.md
index a7fe70f..0ad428f 100644
--- a/README.md
+++ b/README.md
@@ -18,8 +18,9 @@
 
 ## Requirements
 
-* PHP >= 7.2
-* An mbstring extension
+* PHP >= 8.0
+* A mbstring extension
+* An ext-dom extension
 
 ## Installation
 
@@ -109,6 +110,9 @@ $tags = UXML::fromString($xmlInvoice)->toTagsArray($certificate);
 
 $QRCodeAsBase64 = GenerateQrCode::fromArray($tags)->toBase64();
 
+// Invoice Hash: $tags[5]->getValue()
+// Digital Signature: $tags[6]->getValue()
+
 //$QRCodeAsBase64 output will be like this
 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
 ```
diff --git a/src/Helpers/UXML.php b/src/Helpers/UXML.php
index af6c859..5467e5d 100644
--- a/src/Helpers/UXML.php
+++ b/src/Helpers/UXML.php
@@ -325,15 +325,18 @@ public function asXML(?string $version = '1.0', string $encoding = 'UTF-8', bool
      *
      * @param Certificate $certificate
      * @param string|null $invoiceHash the base64 encoded string of the binary invoice hash
+     * @param string|null $digitalSignature the digital signature for the invoice hash
      * @return array
      */
-    public function toTagsArray(Certificate $certificate, ?string $invoiceHash): array
+    public function toTagsArray(Certificate $certificate, ?string $invoiceHash, ?string $digitalSignature): array
     {
         if (!$invoiceHash) {
             $invoiceHash = $this->getXmlHash();
         }
 
-        $digitalSignature = base64_encode($certificate->getPrivateKey()->sign(base64_decode($invoiceHash)));
+        if (!$digitalSignature) {
+            $digitalSignature = base64_encode($certificate->getPrivateKey()->sign(base64_decode($invoiceHash)));
+        }
 
         $issueDate = $this->get("cbc:IssueDate")->asText();
         $issueTime = $this->get("cbc:IssueTime")->asText();
diff --git a/src/Models/InvoiceSign.php b/src/Models/InvoiceSign.php
index a3de50e..2f6622a 100644
--- a/src/Models/InvoiceSign.php
+++ b/src/Models/InvoiceSign.php
@@ -90,7 +90,7 @@ public function sign(): Invoice
     private function generateQRCode(): string
     {
         return GenerateQrCode::fromArray(
-            $this->xmlDom->toTagsArray($this->certificate, $this->invoiceHash)
+            $this->xmlDom->toTagsArray($this->certificate, $this->invoiceHash, $this->digitalSignature)
         )->toBase64();
     }