Massachusetts Institute of Technology
Department of Electrical Engineering and Computer Science
Department of Mechanical Engineering

  6.095 / 2.995Information and Entropy  

Help using this Web site Key System

This Web site has restricted resources and tools, not intended for use by all visitors, that can only be accessed by users to whom the Key Manager has issued an appropriate key. To use these resources you need to sign in by identifying yourself and entering your password.

Types of Access

You may sign in as yourself, using your own personal password.
Groups may be defined to include several people, for example students in a class. Some groups may test membership by asking for a group-specific secret. Others may use a password; if you are in such a group, you will be told the password.
On some sites visitors may access some restricted resources by request, without using a password.
Courtesy Access
On some sites access to some of the restricted resources is given to people using a computer with a domain name or IP address within a particular range. No password is required.

New Users

To request a key as an individual user, with your own personal password, use the New User Key Request Form. When you submit this form an e-mail message will be sent to the Key Manager(s) asking for approval, after which you can use the restricted resources.

Current Users

If you are a current user and your name is not in the pop-up menu on the password form, it may be because you are seeking a resource for which you are not eligible. Each resource has its own key or keys (see below); to get the necessary key, ask the Key Manager.

Individual users: to change your password, your e-mail address, your name, or your password hint, or to start or stop Express Signon, either (1) use the link on the password form, (2) follow the link at the bottom of most pages served by restricted resources, or (3) use this link.

Forgotten Password

If you have forgotten your password, select your name, leave the password field blank, and try to sign in. You will see your password hint, which you yourself defined when you specified your password. If this is enough to remind you of your password, fine; if not, then you will have to contact the Key Manager directly and ask that your name be deleted. Then you can apply for access using a new password just like a new user.

Signing in

If you have already signed in during this session, and have a key for the resource you are seeking, you do not need to do so again. Or if your computer qualifies for Courtesy Access to this resource you do not need to sign in. Otherwise you do.

After identifying yourself and entering your password, you access the restricted resource immediately, and can continue until you quit your browser.

On occasion, you may see the password form in the middle of a session. This happens if you attempt to access a resource for which you have no key (see below). Then you will need to impersonate someone who has a key.

If you see the password form repeatedly, perhaps your browser is configured to reject cookies. Temporary cookies are used to inform the Web site that you have already signed in.

Signing off

Normally you do not need to sign off after accessing these restricted resources. Signing off is automatic when you quit your browser. The next time you launch your browser you will need to sign in again.

Perhaps you want to sign off anyway, without quitting your browser. This may be because you want to let someone else sign in, because you want to see the password form for some reason, or because you are leaving your desk and are concerned about security. At the very bottom of most pages served by restricted resources is a link which will sign you off, or you may use this link.

Express Signon

Express Signon is a feature that allows you to ask your local computer to remember your name and password, and in effect sign you in every time your browser is launched. This is a convenience, but it is also a security risk because anybody else using your computer will automatically impersonate you. Therefore it should not be used in an open office environment. The Key Manager must enable it for your computer, and then issue you the key express after which you can start and stop Express Signon by using the password-change form.

Express Signon automatically stops at the end of each calendar year so after you return from your New Year's Eve partying you will have to start it again.


Different restricted resources are intended for different types of users. Each resource can be accessed using one or more keys, and if you do not have one of them you cannot access that particular resource -- your name will not even appear in the pop-up menu in the password form.

To see which keys you have been issued, look at the Change Form. To request a key you do not have, contact a Key Manager (see the list below).

Here is a list of the keys currently in use for this site, and the corresponding restricted resource(s).

KeyRestricted Activities
staff Access site, Access staff area 
express Use Express Signon 
key-manager Authorize access 
webmaster View technical information 
any-person View site map 
programmer Test code 

Key Manager(s)

Users with the key key-manager may approve new users, delete users, enable and disable Express Signon, and issue and revoke keys. Key Managers cannot change passwords, password hints, or e-mail addresses of individuals (except themselves). Key Managers cannot see your password, even during the approval process.

Key Manager(s) for this site:

If you are already a user but need an additional key, or if you want to return a key no longer needed, or if you want your name removed from the list of users, you should notify a Key Manager (see the list above). You can do this by e-mail, letter, telephone, or direct contact. If there are more than one Key Managers listed, any of them can help you. Be sure to explain the reason for your request.

Privacy of Personal Information

As an individual user, after approval of your request to access restricted resources on this site, some of your personal information is retained and used in the following way:

The file which contains your name, e-mail address, hint, and keys is not encrypted but is restricted so that it cannot ordinarily be accessed except by Key Managers or webmasters (those with FTP or shell accounts). This information will not be made available to other organizations. However, you should be aware that security on the Internet is difficult and computers are sometimes broken into, so you should not depend on this information remaining confidential.

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