How to Retrieve Passwords from active directory (domain)

But iam unable to get the Passwords from Active Directory

this is the code i used for getting usernames

using (var context = new PrincipalContext(ContextType.Domain, "empover.com"))
{
using (var searcher = new PrincipalSearcher(new UserPrincipal(context)))
{
foreach (var result in searcher.FindAll())
{
DirectoryEntry de = result.GetUnderlyingObject() as DirectoryEntry;

DropDownList1.Items.Add("" + de.Properties["samAccountName"].Value);

//DropDownList1.Items.Add("" + de.Properties[" base.Password"].Value);
//Console.WriteLine("First Name: " + de.Properties["givenName"].Value);
//Console.WriteLine("Last Name : " + de.Properties["sn"].Value);
//Console.WriteLine("SAM account name : " + de.Properties["samAccountName"].Value);
//Console.WriteLine("User principal name: " + de.Properties["userPrincipalName"].Value);
//Console.WriteLine();
}
}
}