Hello Curtis,
 
The concept of LOCK was to allow an I_T nexus to create a fixed association with a particular set of data encryption parameters at a specific generation (key instance counter).  This association is saved with the I_T nexus (see subclause 4.2.21.7) not with the set of data encryption parameters because more than one I_T nexus can be associated with a set of data encryption parameters (one as the creator, others using the PUBLIC scope).  It was not an oversight to not include the lock bit in the data encryption parameters structure, it doesn't belong there.  Consider the example where I_T nexus A sends a SPOUT command to create a set of data encryption parameters with a scope of ALL I_T_NEXUS but does not set the LOCK bit, then I_T nexus B sends a SPOUT command with a scope of PUBLIC with the LOCK bit set to 1.  In this example, A is not locked to the parameters but B is.  What would you put in the lock parameter if it was part of the set of data encryption parameters?
 
You may want to consider fixing the problem by introducing the concept of a master key instance counter in 4.2.41.10 that is not associated with any set of data encryption parameters.  It would be incremented and inserted into the set of data encryption parameters each time one is created.  You would also need to modify the test in 4.2.21.11 such that a lock violation occurs if the I_T nexus is locked and the data encryption parameters have been released.
 
Paul Entzel
 
From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Ballard, Curtis C (StorageWorks)
Sent: Monday, March 31, 2008 2:51 PM
To: 't10@t10.org'
Subject: RE: SSC-3: Late Letter Ballot comment

Kevin,

 

I looked into this a bit and came to a different conclusion.

 

You reference section 4.2.21.6 on Managing keys within the device server and the section on when to release a set of data encryption parameters which does not discuss turning off encryption.

 

I believe the section we need to reference is a little further into 4.2.21.6 at that start of document page 56 in SSC3r04a.pdf where it discusses what to do when both the ENCRYPTION MODE and the DECRYPTION MODE are set to DISABLE which is the encryption off condition.

 

"If a device server processes a Set Data Encryption page with the ENCRYPTION MODE field set to DISABLE and DECRYPTION MODE field set to DISABLE or RAW, the physical device shall:

 

a)release any resources that it had allocated to store data encryption parameters for the I_T nexus associated with the SECURITY PROTOCOL OUT command and shall change the contents of all memory containing a key value associated with the data encryption parameters that are released; and

 

b)establish a unit attention condition . . ."

 

The statement "data encryption parameters" was referenced to 4.2.21.8 earlier in that clause so if we follow that reference we find that virtually all of the settings that a host can establish are included in the data encryption parameters including the key instance counter which is tied to locking.  When both modes are set to DISABLED which is what has to be done to turn encryption off, then everything in the set of data encryption parameters is released so all of those values are gone.  If the counter is gone along with all the other parameters I don't see how the parameters can possibly continue to be associated with that I_T nexus.

 

According to my notes we discussed at the last SSC-3 meeting that "LOCK" should also be included in the data encryption parameters but wasn't due to an oversight.  If it had been then it would be clear that "LOCK" is gone when the encryption parameters are released.

 

I'm concerned that this behavior seems to be inconsistent with the introduction to 4.2.21.11 which discusses exactly the case of resources being released and the UA not detected and suggests that LOCK solves the issue.

 

If the intent is that LOCK persist when the rest of the parameters are released then I don't think the change is as simple as you suggest.  I think that we would need to modify 4.2.21.6 to indicate that the key instance counter is not released with the rest of the parameters if LOCK is set to one, but instead is incremented.  That way the test described in the section on locking where a changed key instance counter triggers the CHECK CONDITION will still work.  We might also have to modify some text describing releasing resources when limited resources are exhausted to make it clear that parameters containing a LOCK bit set to one can't be released (I have some concerns with whether that can be required).  There might also be other sections that talking about releasing parameters that would need examined.

 

This one looks to me like it's going to take a proposal to address.

 

Curtis Ballard

Hewlett Packard

 

From: owner-t10@t10.org [mailto:owner-t10@t10.org] On Behalf Of Kevin D Butt
Sent: 20 March 2008 21:48
To: t10@t10.org
Subject: SSC-3: Late Letter Ballot comment


I received communication from an ISV today related to Encryption mode locking (4.2.21.11).  They were unable to determine if the locking applied when the data encryption parameters were set such that encryption/decryption is turned off.  In a close reading this clause refers to "...locked to that set of data encryption parameters and key instance counter value until a hard reset condition occurs or another [SPOUT command is received]"

In 4.2.21.6 Managing keys within the physical device, where it describes when to release a set of data encryption parameters, there is no mention of turning off encryption.  Therefore, the locking does apply to the saved set of encryption parameters even when encryption is turned off.  This is indeed the desired behavior.  However, it is not clear to the casual or novice standards reader that this is the case.

Proposed Solution (Editorial):
In 4.2.21.11, p2, add a new sentence after s1:
The LOCK bit in the Set Data Encryption page is set to one to lock the I_T nexus that issued the SECURITY PROTOCOL OUT command to the set of data encryption parameters established at the completion of the processing of the command.  A set of data encryption parameters are established and locked even if the ENCRYPTION MODE is set to DISABLE and the DECRYPTION MODE is set to DISABLE.

Thanks,

Kevin D. Butt
SCSI & Fibre Channel Architect, Tape Firmware
MS 6TYA, 9000 S. Rita Rd., Tucson, AZ 85744
Tel: 520-799-2869 / 520-799-5280
Fax: 520-799-2723 (T/L:321)
Email address: kdbutt@us.ibm.com
http://www-03.ibm.com/servers/storage/