Update from SHA-1 to SHA-256 for improved security

Co-authored-by: BillWagner <[email protected]>

Author: Copilot

samples/snippets/visualbasic/VS_Snippets_VBCSharp/VbVbalrStrings/VB/Class3.vb

@@ -82,11 +82,11 @@ Class Class1f51e40a2f8843e2a83e28a0b5c0d6fd
             ByVal key As String, 
             ByVal length As Integer) As Byte()
 
-            Using sha1 As SHA1 = SHA1.Create()
+            Using sha256 As SHA256 = SHA256.Create()
                 ' Hash the key.
                 Dim keyBytes() As Byte = 
                     System.Text.Encoding.Unicode.GetBytes(key)
-                Dim hash() As Byte = sha1.ComputeHash(keyBytes)
+                Dim hash() As Byte = sha256.ComputeHash(keyBytes)
 
                 ' Truncate or pad the hash.
                 ReDim Preserve hash(length - 1)