Question

We are developing a web application that uses forms authentication and the ActiveDirectoryMembershipProvider to authenticate users against the Active Directory. We soon found out that the provider does not allow a blank/empty password to be specified, even though this is perfectly legal in the Active Directory (provided a preventative password policy is not in place).

Courtesy of reflector:

private void CheckPassword(string password, int maxSize, string paramName)
{
    if (password == null)
    {
        throw new ArgumentNullException(paramName);
    }
    if (password.Trim().Length < 1)
    {
        throw new ArgumentException(SR.GetString("Parameter_can_not_be_empty", new object[] { paramName }), paramName);
    }
    if ((maxSize > 0) && (password.Length > maxSize))
    {
        throw new ArgumentException(SR.GetString("Parameter_too_long", new object[] { paramName, maxSize.ToString(CultureInfo.InvariantCulture) }), paramName);
    }
}

Short of writing our own custom Provider, is there any way to override this functionality using the magic of .NET?

Answer 1

I don’t beleive you could change this behaviour without creating a derived class and overiding every method that calls the private CheckPassword method. I would not recomend this option however, i would recomend that you review your design and question whether it is approriate to allow blank passwords in your application. Whilst they are valid in AD it is unusual for this to be allowed in practice and it does impact other things in a windows network, e.g. i think the default settings for network file shares disallow any user with a blank password from connecting to the share.