Private Function GeraSHA256(ByVal Chave As String) As String
    Dim uEncode As New UnicodeEncoding()
    Dim Hash() As Byte
    Dim SHA As New SHA256Managed()
    Dim Bytehash() As Byte
    Hash = uEncode.GetBytes(Chave)
    Bytehash = SHA.ComputeHash(Hash)
    Return Convert.ToBase64String(Bytehash)
End Function