Password Uniqueness in Windows NT

• Microsoft Windows NT operating system version 3.1
• Microsoft Windows NT Advanced Server version 3.1

SUMMARY

The Password Uniqueness parameter in Windows NT can confuse users. There is no direct association between this value and the number of passwords that a specific user has previously used.

MORE INFORMATION

Let's suppose that Password Uniqueness is set to 3. This does not mean that at the third password change I can use an old password, or that that after using three passwords I can use the first one again.

The Password Uniqueness parameter works as follows:

   First password:  One                Passwords saved: <>

   First password change
     New password:  Two                Passwords saved: <One>

   Second password change
     New password:  Three              Passwords saved: <One,Two>

   Third password change
     New password:  Four               Passwords saved: <One,Two,Three>

   Fourth password change
     New password:  Five               Passwords saved: <Two,Three,Four>

A better way to explain this is to regard the Password Uniqueness number as the number (n) of entries in a fictitious table, where the passwords in this table cannot be used. If you add to this your current password, plus the new password that you will use, you get n+2 different passwords, and not n different passwords.

Be aware that if you want to keep n different passwords, Password Uniqueness must be set to n-2. Be aware also that n can be any number from 1 to 8.

Workaround

If you mistakenly set up a number and you don't want that to be your standard, you can change it, and the oldest entries from that table will be removed so you can use those passwords.

To change Password Uniqueness:

1. From User Manager for Domains, select the Policies menu.

2. Choose Account.

3. Change your password uniqueness number in the Password Uniqueness box.

4. Choose OK.