First of all, sorry I didn't expose completely my problem. My C# aplication takes some data from one part, and after some operations I have to store my new data. The simplest way is in my view an Access database. I create the database and tables by code, but I also wanted the database to be protected by password from the moment I created it. I had some luck and tried :
ADOX.CatalogClass cat = new ADOX.CatalogClass();
cat = null;
cat.Create("Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + new_path + "\\" + mdb_name + ".mdb;" + "Jet OLEDB:Database Password=my_password;Jet OLEDB:Engine Type=5");
and it worked.
PS: thanks for the warning about security.Even though I don't know what problems you are talking about I'll be searching...