Correct root-instance paranoia

[wiki.git] / doc / root-instance.mdwn

diff --git a/doc/root-instance.mdwn b/doc/root-instance.mdwn
index 46666b15fe29ea57a71c0dc3c6603f13acf1353b..1d43b2368cb5d91538e50aad00681cc1662c7e11 100644 (file)
--- a/doc/root-instance.mdwn
+++ b/doc/root-instance.mdwn
@@ -36,23 +36,19 @@ wisest idea to let servers that you're asking hundreds of people to
 log into and use be controlled by a password you're typing everywhere.
 
 So you get a root instance, and only type the root instance password
-on computers you trust and only when you need to. Many people only
-ever type it on their laptop, or on a freshly booted Live CD. Some
-people feel comfortable typing it on a few private Athena workstations
-(SIPB office heads are a common choice), but if an attacker has stolen
-your regular (null instance) password and installed a keylogger on
-your account, it doesn't matter where you're logging in if it's still
-your Athena account.
+on computers you trust and only when you need to.  You should only
+type your password on a computer that you trust, such a private laptop
+or workstation.  If you have access to physical hardware that you
+trust, but not a trusted installation, you can use a printed LiveCD,
+or a one-time LiveUSB as created by hardware that you trust.
 
 You can also make things in Moira or AFS owned by your root instance,
 if you don't want your null instance to be able to mess with mailing
 lists or lockers. For Moira, make them owned by
-`KERBEROS:yourname.root@ATHENA.MIT.EDU`. (For legacy Kerberos 4 reasons,
-Moira and AFS both use a dot instead of a slash to separate the
-principal and the instance.) For AFS, ask accounts or afsreq to get
-you a 'pts id', basically an account with the AFS servers, and then
-you can give bits to yourname.root and start blanching your root
-instance onto AFS groups.
+`KERBEROS:yourname/root@ATHENA.MIT.EDU`. For AFS, ask accounts or
+afsreq to get you a 'pts id', basically an account with the AFS
+servers, and then you can give bits to yourname.root and start
+blanching your root instance onto AFS groups.
 
 To use another instance, just specify it to the kinit command, e.g.,
 `kinit joeuser/root`.
@@ -100,9 +96,27 @@ extra instance's password instead.
 
 ## Getting them
 
-You need to show up in person to IS&T User Accounts in N42 with a
+You need to show up in person to [IS&T User
+Accounts](http://ist.mit.edu/support/accounts) in
+[E17](http://whereis.mit.edu/?go=E17) during business hours with a
 photo ID to obtain new Kerberos identities. For the reasons described
 above, being in control of your null instance and sending a zephyr or
 authenticated e-mail with it does not mean that you can go ahead and
 make changes to your root or extra instance too.  While you're there,
 be sure to ask for a pts id, if you want to use your tickets with AFS.
+
+## Upgrading cryptographic strength
+
+You should change your root instance’s password with a command like this, to upgrade your key from critically weak DES encryption algorithm to strong AES encryption:
+
+    kadmin -p andersk/root -q 'cpw -e aes256-cts:normal -e aes128-cts:normal andersk/root'
+
+(Note: This might make your password incompatible with a [handful of services](http://debathena.mit.edu/trac/ticket/529) that you should not have been using with your root instance in the first place.)  You can confirm the change with
+
+    kadmin -p andersk/root -q 'getprinc andersk/root'
+
+which should list a line like
+
+    Key: vno 4, aes256-cts-hmac-sha1-96, no salt
+
+If you change your password again, you will need to specify your desired enctypes with the -e option; otherwise, they will be reset to the defaults.