Tuesday, April 29, 2008

Follow-up to Hitachi's Announcement of AES-256 Encryption Within a Hard Disk

As many readers noticed, last week Slashdot covered a announcement that Fujitsu is the first to offer 256-bit AES encryption in their MHZ2 CJ Series 320 GB 2.5" hard drives.  As chair of the IEEE P1619 Security in Storage Working Group, I felt an obligation to get more details on exactly what 'AES-256' encryption means. So I clicked on the handy box to submit questions, and got the following responses from Fujitsu:
1. What is the mode of operation for the AES block cipher (e.g., ECB, CBC, CTR, etc)?
===> We don't disclose this.

2. How are the 256-bit AES keys managed?
===> We don't disclose this.

3. Is Fujitsu considering NIST FIPS 140-2 certification for this disk drive (like Seagate is doing)?
===> under consideration.  
I had similar questions about Seagate's Full Disk Encryption (FDE) hard drive, and couldn't get any answers there, either.  According to AES Certificate #587, Seagate is using Electronic Code Book (ECB) for their FDE.  Unfortunately, ECB is a very insecure mode-of-operation, one that I hope NIST eventually withdraws.  To visually see what I mean, take a look at the ECB encryption of Tux the penguin.  The latest rumors I've heard is that Seagate is moving to cipher-block-chaining (CBC) encryption (a much more secure mode-of-operation) for subsequent encrypting hard disks.  Fujitsu will likely take a similar course, although there is expected to be some flexibility in the algorithms.

In contrast, tape drive vendors have been much more open about the details of their tape encryption. According to the LTO-Technology page, LTO uses the AES-GCM mode as specified in IEEE P1619.1 (soon to be published as IEEE Std 1619-2007).  Sun's T10000 uses AES-CCM, both as specified in P1619.1 and in NIST SP 800-38C.  IBM's TS1120 also uses AES-GCM.

So why aren't hard disk vendors disclosing the technical details about their encryption implementation?

Here are my thoughts:
  1. Hard disk vendors don't think that the mode of encryption is too important because it is difficult to get direct access to the encrypted data (this would require bypassing the firmware or putting the hard disk on a spin stand)
  2. Hard disk vendors are afraid that weaknesses will be found in their encryption mode, whether real or perceived
  3. There are no good standards to use for hard disk encryption
While it is true that most users don't understand enough about encryption to even know what a mode-of-operation is, I believe that these details will become increasingly important as buyers become better educated and demand open details about the encryption.  Otherwise there is no way to know whether you've been sold snake oil that doesn't actually provide measurable benefits (for example, weak ECB encryption of the entire hard disk using the otherwise strong AES block cipher).

Concerning standards, this is an example of how the late arrival of IEEE 1619 has caused confusion in the storage encryption industry.  When IEEE 1619 start about 6 years ago, the goal was to create a strong encryption standard suitable for data storage devices.  First came the wide-block EME mode.  This mode fell when Antoine Joux found a vulnerability that sent Shai Halevi and Phil Rogaway back to the drawing board.  Next was the LRW mode.  This fell when Niels Ferguson of Microsoft noted in Crypto 2006 that you can leak the tweak key if encrypted with itself (Microsoft has no control over where the keys are).  About this same time, the Trusted Computing Group wanted to endorse LRW (this was dropped).  About two years ago during the LRW unrest, Mart Somermaa pointed the group to the XEX mode as proposed by Phil Rogaway.  The P1619 group added ciphertext-stealing to this mode and called it XTS-AES.  

The XTS-AES algorithm was approved last December by IEEE as part of IEEE 1619-2007, and is nearly published.  After it is published, IEEE will submit XTS to NIST for consideration as an Approved Mode of Operation for FIPS 140-2.  If NIST accepts XTS, then this will become an excellent mode for hard disk vendors to consider.

Saturday, April 26, 2008

Fixing up the Mac Key Bindings for Windows Users

[Note: Edited on 2010-02 to switch the order of the shift and command key modifiers.  Apparently, Mac OS is particular about the order.]

[Edited on 2010-10-22 to describe how to use TextEdit to apply this key mapping]
[Edited on 2010-11-12 to mention that TextEdit sometimes adds a .txt extension]

I'm a longtime Windows user who recently purchased a Macbook. Overall I'm very impressed with the machine, but it does have a learning curve, especially for the key bindings.

The first thing I noticed was that the Macbook does not have the Del and Ins keys at all, and the Home, End, PageUp and PageDown keys require pressing 'Fn' and then an Arrow key (which is understandable because the keyboard on a small Macbook is somewhat cramped -- also, I've asked a couple users who have not used PCs much before using a Mac, and they did not even know these keys existed, or what they would do with them)

However, when I'm not on the road, I like to use a nice full sized Microsoft Natural Keyboard, to reduce tendinitis. As a (former) hard-core programmer, I very extensively use the Home, End, PageUp and PageDown keys to quickly navigate code or text documents. I was very dismayed to discover that Apple pretty much doesn't do anything with these keys.

In hunting through all the configuration options, I noticed that you can reconfigure a lot of key mappings through the System Preferences utility (go to the apple in the upper-left corner, select System Preferences..., click on Keyboard & Mouse, and click the Keyboard Shortcuts tab). This was useful for a start, but I quickly determined that the Mac wouldn't allow me to bind keys to any of the 6 special keys (Home, End, PageUp, PageDown, Delete, Insert). This made me sad.

I did discover, however, that it is possible to switch the Control and Command keys. This is a big help because now all the windows favorites like Ctrl+c for copy, Ctrl+v for paste, Ctrl+x for cut, and Ctrl+z for undo now work the same on both systems. I still switch frequently between Windows and Mac platforms, so it's very nice to have the same key mappings.

Most recently, I discovered that there is a special file you can create that allows special mappings to the 6 special keys. This made me happy. I was now able to get much closer to having a unified key mapping. For more details, see this article.

To do this, create a new file called ~/Library/KeyBindings/DefaultKeyBinding.dict and put the following text into it (You'll probably have to create the directory the first time -- this is okay).

/* ~/Library/KeyBindings/DefaultKeyBinding.Dict
This file remaps the key bindings of a single user on Mac OS X 10.5 to more closely
match default behavior on Windows systems.  This particular mapping assumes
that you have also switched the Control and Command keys already.

This key mapping is more appropriate after switching Ctrl for Command in this menu:
Apple->System Preferences->Keyboard & Mouse->Keyboard->Modifier Keys...->
Change Control Key to Command
Change Command key to Control
This applies to OS X 10.5 and possibly other versions.

Here is a rough cheatsheet for syntax.
Key Modifiers
^ : Ctrl
$ : Shift
~ : Option (Alt)
@ : Command (Apple)
# : Numeric Keypad

Non-Printable Key Codes

Up Arrow:     \UF700        Backspace:    \U0008        F1:           \UF704
Down Arrow:   \UF701        Tab:          \U0009        F2:           \UF705
Left Arrow:   \UF702        Escape:       \U001B        F3:           \UF706
Right Arrow:  \UF703        Enter:        \U000A        ...
Insert:       \UF727        Page Up:      \UF72C
Delete:       \UF728        Page Down:    \UF72D
Home:         \UF729        Print Screen: \UF72E
End:          \UF72B        Scroll Lock:  \UF72F
Break:        \UF732        Pause:        \UF730
SysReq:       \UF731        Menu:         \UF735
Help:         \UF746

NOTE: typically the Windows 'Insert' key is mapped to what Macs call 'Help'.  
Regular Mac keyboards don't even have the Insert key, but provide 'Fn' instead, 
which is completely different.

"\UF729"   = "moveToBeginningOfLine:";                       /* Home         */
"@\UF729"  = "moveToBeginningOfDocument:";                   /* Cmd  + Home  */
"$\UF729"  = "moveToBeginningOfLineAndModifySelection:";     /* Shift + Home */
"@$\UF729" = "moveToBeginningOfDocumentAndModifySelection:"; /* Shift + Cmd  + Home */
"\UF72B"   = "moveToEndOfLine:";                             /* End          */
"@\UF72B"  = "moveToEndOfDocument:";                         /* Cmd  + End   */
"$\UF72B"  = "moveToEndOfLineAndModifySelection:";           /* Shift + End  */
"@$\UF72B" = "moveToEndOfDocumentAndModifySelection:";       /* Shift + Cmd  + End */
"\UF72C"   = "pageUp:";                                      /* PageUp       */
"\UF72D"   = "pageDown:";                                    /* PageDown     */
"$\UF728"  = "cut:";                                         /* Shift + Del  */
"$\UF727"  = "paste:";                                       /* Shift + Ins */
"@\UF727"  = "copy:";                                        /* Cmd  + Ins  */
"$\UF746"  = "paste:";                                       /* Shift + Help */
"@\UF746"  = "copy:";                                        /* Cmd  + Help (Ins) */
"@\UF702"  = "moveWordBackward:";                            /* Cmd  + LeftArrow */
"@\UF703"  = "moveWordForward:";                             /* Cmd  + RightArrow */
"@$\UF702" = "moveWordBackwardAndModifySelection:";   /* Shift + Cmd  + Leftarrow */
"@$\UF703" = "moveWordForwardAndModifySelection:";   /* Shift + Cmd  + Rightarrow */
Remember: These key mappings assume that you've switched Control and Command. If you don't want to make this switch, replace each @ (command) with ^ (control).

Here are steps to take to apply these changes:
  • Open TextEdit under the Applications folder.  If TextEdit was already open, create a new document using File->New.  There should be a window labeled 'Untitled'.
  • Select the text within the window above, copy it, and then paste it into your new TextEdit window.
  • In TextEdit, convert this to plain text (the default is rich text) by selecting Format->Make Plain Text.
  • Next, select File->Save As...  In the "Save As" dialog box, navigate to your home directory (look under PLACES on the left side for a house picture that has your name next to it).  In your home directory, double-click on the Library folder.  If you see a KeyBindings folder then double-click on it.  If not, then click on "New Folder" (within the Library directory), name the new folder KeyBindings (with no space), and then double-click on it.  Type DefaultKeyBinding.dict for the filename (at the top) and then click Save.
  • Warning:  TextEdit will sometimes try to 'help' you by appending a .txt extension to the filename.  Make sure this doesn't happen.  If asked to use a .txt extension, tell TextEdit to instead use .dict.  It will not work if you use .txt.  If you have trouble, see comment by Nathan below.
  • Before these changes take effect, you need to log out and then log back in.

There you have it! I know this emulation isn't perfect (not all applications honor this mapping), but it's a good start. Please drop comments if you have any questions or suggestions for improvements.

Tuesday, April 8, 2008

RSA 2008: Cryptographer's Panel

As one of the great highlights of the RSA Conference is the cryptographer's panel with the great experts of modern public key cryptography: Whitfield Diffie, Martin Hellman of Diffie-Hellman fame (discrete log crypto) and Ron Rivest and Adi Shamir of RSA fame (crypto based on the integer factorization problem -- used in SSL).

This is a rough draft post that will be cleaned up later, but contains the last part of the discussion:

Question from Burt: Where would you put your research effort?
Diffie: I'd put research into genetics - We'll see the first child made from two women, showing that men are an expensive and unnecessary thing to have around.
Hellman: We need to become more rational in our approach to security

Closing remarks:
Diffie: I'm optimistic about this subject. People are going to get along just fine -- cyber security is very important. The most important thing in the 20th century is client server computing. By putting important information onto a single computer, it's possible to control access. -- Something's going to happen that we don't expect, from younger people
Hellman: Don't be afraid to tackle problems
Rivest: (countering Diffie): There is a lot of cryto still to be discovered. We're still at the early stages of tying worst-case complexity to best-case complexity -- how to run crypto protocols in parallel so that they don't interfere -- we need the secure platform -- next problem is user interfaces
Shamir: It's about subtlety behind the schenes --- multiple lines of defense -- most of the basic elements are there. But we haven't reached nirvana -- we need to develop tools and techniques -- a GPS for data, need the ability to located where your data is. Use 160-bit sha-1 summary to help locate this data. This could help the information management problem

Burt: 1024-bit RSA -- how much longer before the publicly announced factorization
Shamir - next year
Hellman - I was at Certicom -- Elliptic curves have been rock-solid since inception
Rivest - Use Moores law - There are low-probability algorithms that are hard to predict
Burt -2010 is the transition to 2048 bit keys

These guests will be in the crypto commons for more discussion.

My RSA Conference 2008 Schedule

I will be at the RSA Conference from Monday April 7 to Friday.  For those who would like to meet up during this week, here is my anticipated schedule:

(I'll update this entry periodically as things change...)

10:25 - 11:20: Cryptographer's Panel (with Diffie, Hellman, Rivest,  and Shamir (no Adleman))
11:20 - 1:30: Lunch -- Meet at the nCipher exhibit
1:30 - 2:40: RED 309 - Real World Key Management: News from the trenches
3:00 - 3:50: RED 309 - Cryptographic Security for Ruby on Rails Web Services
4:10 - 5:20: RED 309 - Security Usability: The New Challenge (with Phillip Hallam-Baker)
5:40 - 6:30: RED 309 - Beyond the Coding Errors: The Complete View of Software Security
6:30 - 9:00: Dinner (TBD)

8:00 - 8:50: RED 300 - Improved AES Implementations
9:10 - 10:20 RED 300 - Public Key Encryption with Special Properties
10:40 - 11:50 RED 300 - Side Channel Cryptanalysis
2:00 - 6:00 Key Notes
6:30-7:30 "Dinner for 6"

8:00 - 8:50: RED 310 - High-Speed Risks in 802.11n Networks
9:10 - 10:20 RED 308 - Extended Validation: Raising the Bar for Internet Trust
10:40 - 11:50 RED 308 - PCI DSS Security Standards Foundation and future
2:00 - 5:00 Keynotes

9:00 - 9:50: RED 308 - Standardizing Key Management for Trusted Storage
10:05 - 10:55: RED 308 - The New FIPS 140-3 Standard
11:10 - 12:00 RED 308 - What's New with XACML, the Access Control Standard?
Catch bus for flight: around 1:00 pm

If anyone is interested in meeting up, please shoot me an e-mail or give me a call on my cell phone: 303-717-2717