diff --git a/repository/Grafoscopio/ExternalApp.class.st b/repository/Grafoscopio/ExternalApp.class.st
index 852d684..6c376af 100644
--- a/repository/Grafoscopio/ExternalApp.class.st
+++ b/repository/Grafoscopio/ExternalApp.class.st
@@ -41,6 +41,14 @@ ExternalApp class >> configurePandoc [
 
 ]
 
+{ #category : #installation }
+ExternalApp class >> file: aFileName hasHash: aSHAString [
+	
+	aSHAString  = (SHA1 new hashMessage: aFileName asFileReference binaryReadStream contents) hex
+		ifFalse: [ ^ false ]
+		ifTrue: [ ^ true ].
+]
+
 { #category : #installation }
 ExternalApp class >> installSQLite32Bits [
 	"I dowload the SQLite binary for the hosting platform, uncompress it and made it available as with the name