Older blog entries for MichaelCrawford (starting at number 55)

I'm very close to having the passphrase application for FireWire Encrypt working on Mac OS 9. There is documentation and sample code for doing FireWire on OS 9, but the doc is very terse and the sample code is very complex, and doesn't quite apply to what I'm trying to do.

I have all the code written that I think should be necessary, but it is not working quite right.

I got the Windows driver development kit so I could learn to do FireWire on Windows. After I do Windows (which I expect to be my most difficult platform) I will do it on Linux. I run Slackware on a Pentium III box and Debian Woody on my Power Macintosh 8500, so I can support Linux for both x86 and PowerPC.

This will be WiebeTech's first product with explicit Linux support. It's happening mainly because I'm into Linux, and I reasoned with my client that Linux people are more security conscious and so disproportionately likely to be interested in the product.

While you can get free hard disk encryption with the GNU/Linux Crypto API, installation and configuration are somewhat daunting. I figure we'll make some Linux sales because our product is easier to use.

Bonita and I are going up to Nova Scotia for a few days. I hadn't expected to go, but Bonita was worried about driving by herself because our winter has been fierce at times and it's very, very cold right now.

So once I'm done with this diary entry I'm going to get both my laptops prepped to work on the road (I have a 450 MHz Pentium III Compaq Presario 1800T and a 700 Mhz OS X/OS 9 iBook.

The Compaq used to be my main development machine. I bought it just before I moved to Newfoundland, and found it very handy when I was traveling around so much. But Bonita needed a machine so I took all my whacky stuff off of it and configured it the way she likes it. I only get to use it when I travel nowadays.

mobius said:

I'd also forgotten how ugly the Advogato layout is. Yick.

That's funny, because I regularly point out Advogato to my friends as an example of particularly tasteful web design.

Someone emailed me just now to tell me that a google search for how to get ranked on internet turns up my article How to Promote Your Business on the Internet as the number one search hit, ahead of 551,000 other pages.

Me: Did you know that X-rays and gammar rays are just light? They're just higher frequency light.

Bonita: You say the sexiest things.

Happy News!

It seems that the firewire encryptor I wrote for WiebeTech is being enthusiastically received at the MacWorld Expo. There is every sign that my hard work and my client's investment will result in a commercial success.

Bonita and I are very excited about the news, as I imagine my client must be.

I issued my first press release ever, and have been faxing it to newspapers around Maine:

There is news coverage about FireWire Encrypt at MacObserver and MacCentral.

I think MacObserver was confused when James called the passphrase interface an "applet". In their article they call it a "Java applet". It's actually written in C++ and is a vanilla carbon application; we call it an applet because it so simple. I used ZooLib so I can make the UI for Windows and Linux from the same sourcebase.

7 Jan 2003 (updated 7 Jan 2003 at 01:44 UTC) »
Embedded Systems Development

So Nate Myers emailed me today to ask why I didn't just post a web page with the text of WiebeTech's press release about the product I developed for them instead of all these cryptic hints in my diary.

And I responded to Nate that his email was the first that I'd heard of WiebeTech announcing the product, and I didn't want to announce it before WiebeTech did.

(WiebeTech's press release is a Word document. Sorry. I'll ask them if it's OK that I post an HTML version.)

WiebeTech's FireWire Encrypt(TM) is an implementation of the Advanced Encryption Standard embedded in an Oxford 911 FireWire/IDE bridge. It encrypts each sector of the user's hard drive using the Rijndael block cipher.

It is designed to be portable and easy to use. Easy to use because the only software the user needs to install is a small applet to enter the passphrase. There is no complicated operating-system level software to install or configure. Portable because FireWire is a hot-pluggable technology for external devices.

A good use for the product would be to safely take confidential source code or business plans home from work on a hard drive, without fear that your secrets would be revealed if the hard drive were stolen.

WiebeTech will be demonstrating it on Mac OS X, but I plan to support it from Linux and Windows by the time the product is released to the public.

And yes, we're applying for a patent. But we're not applying for an algorithm patent. I disagree as much as anyone here with the abusive patents that the USPTO has been issuing the last few years, but I think this sort of thing is appropriate to patent.

Getting it to actually work was definitely novel and unobvious, and I believe that users will find it useful.


Someone emailed to ask me about what encryption mode FireWire Encrypt uses, and I thought I should post that here too.

It uses Cipher Block Chaining and Initialization Vectors.

Cipher block chaining is applied to each 16-byte block of a 512-byte disk sector. What you do is XOR the previous block's ciphertext over the next block's cleartext before encrypting subsequent blocks. This has the effect of making identical blocks of cleartext encrypt differently.

CBC can't be carried between disk sectors because the host can read or write each sector independently. To make identical sectors encrypt differently, I use an initialization vector.

What you do is XOR some value over the first block of cleartext in each sector before you encrypt it. The IV doesn't have the be kept secret. It doesn't even really matter what value you use, as long as each sector gets a unique IV. The simplest thing to do is to use the sector number as the IV.

I felt that was the best thing to do after reading about block cipher modes in Bruce Schneier's Applied Cryptography.

Initialization vectors work better than you might think because one of the characteristics of a strong encryption algorithm is that flipping a single bit in the plaintext will flip, on the average, half the bits in the ciphertext, with the bits that get flipped being apparently randomly distributed. So having only one bit of the IV being different from sector to sector will dramatically change the ciphertext.

I was also asked if the product checks that the user has entered the correct password. The version that will be demoed at MacWorld doesn't do that yet, but I think that verifying the password is very important for making the product accessible to regular users. I know a simple way I can do that, and plan to check passwords in the final released product.

Embedded Systems Development

Well I got my product ready for MacWorld. I delivered the show build at 9:30 am this morning. Fortunately my client didn't have to fly out to SFO until this afternoon, so he was able to install and test it. He said it worked well.

If you want to see what I've been working on, stop by WiebeTech booth #1651 and ask James to show you the "technology demonstration".

I pulled all nighters two nights in a row to make the show deadline, with only four hours sleep in the middle. That's starting to get hard on an old guy like me. (I'm 38. I wouldn't have thought that was too old to stay up all night but it's starting to feel that way).

I'm glad I delivered a test build last night for my client to try out before the final delivery, because he had some trouble and I had to figure out what was wrong. We were planning to stay up all night while I sent him diagnostic builds but fortunately it was just a couple simple problems that didn't take us long to figure out.

I was really worried though because what he tested wasn't really of good enough quality to demo at a trade show, and I was worried sick some awful bug would happen. But in the end everything went well. It took all night because there was a lot of work to do but there were no real problems encountered.

In the end I was able to just deliver the demo and go to bed, and my client was able to run it just fine.

Some work remains before the product can be made an end-user product, but I know how to do what needs to be done. One of the chief advantages of my product over competing products will be that it should be so easy for regular users to use. It's not quite there yet.

Now I wait anxiously to hear what the reaction from the press and the public will be.

Embedded Systems Programming

Well, the snowstorm wasn't so bad, only a few inches fell, and the power outage I feared didn't happen.

That's good, because I'm trying to get a demo of my application for my client to show at his booth at the MacWorld Expo. That happens this week, and my client is flying out to San Francisco tomorrow morning.

I had all kinds of trouble. I got stuck this morning and posted a desperate question on the Usenet this morning and then caught about five hours sleep while I hoped a clueful response would be posted.

The clue I needed was indeed posted when I sleepily went back to work. A little googling got me the info I needed to get back on track again.

I'm now doing a little testing before sending my client his first try at my application working in its entirety. There is still a little more work before it will be showable, but I hope to have that done by midnight.

Not a moment too soon, eh?

I think my client will be posting a press release about my product on his website when the MacWorld Expo opens Tuesday. When that happens I can finally tell you all what I've been working on these last three months.

It's nice to see it all finally coming together after having solved so many difficult problems. It's been quite a learning experience.

Predictions of Snow

By noon or so tomorrow I need to deliver a build of my embedded application that my client intends to demo in his booth at the MacWorld Expo next week.

But a foot of snow is expect to start falling at midnight tonight. I'm concerned about losing power.

We were more concerned about being stuck in the house without any food so we went to the grocery store to stock up. Apparently the entire town had the same idea, the place was packed.

Whenever there's a particularly bad snowstorm we can't get out for the next day because it takes that long for the plow man to make it to our lane. It's just because it takes him so much longer to plow each of his customers.

Some happy news, in a couple days I will be able to tell you what the embedded product is I've been working on. If you will be attending MacWorld, you could go see it demonstrated at my client's booth.


My application requires a small user interface on the host computer it's attached to. I am using ZooLib to do the UI. Since CodeWarrior 6 doesn't work so well on OS X and I don't have time to purchase the update, I tried using Project Builder. But ZooLib wasn't happy with Project Builder.

I am managing to use CodeWarrior for this task but I'd really like for ZooLib to support Project Builder. So next week I'm going to fix the problems.

I had a problem that I'm pretty sure is a bug in Project Builder. After I posted to a Mac programmer's newsgroup someone from Apple wrote to ask if he could help. Tomorrow I'm going to send him my project and my sources.

I had a long talk with Andy Green last night, and we've decided to make the push for a new ZooLib release soon. Basically as soon as all the existing demo code will build and run cleanly in all the target compilers.

I'm also going to try again to get ZooLib to build on Windows under MingW. That would allow one to build ZooLib on all the supported platforms for which gcc is available using gcc. Classic Mac OS doesn't have gcc but you could build a carbon app under OS X using gcc and run it on Systems 8 or 9.

My New Year's Resolution

Is to finish writing The ZooLib Cookbook by the end of the year. (It is under the GNU Free Documentation License.)

More generally, I want to stop letting my economic troubles prevent me from finding the time to do all the things I want to do. If I write just a little bit each week. I should be able to finish the book in a year no matter how busy things get.

There is other writing I want to do too, and I want to finish grinding my telescope mirror. I should be able to find the time to do all that.

I corresponded with a technical publisher about the possibility of them publishing a dead-tree edition of The ZooLib Cookbook. They were interested, but they didn't feel ZooLib was popular enough yet that they would sell enough copies to justify the cost of publication.

I have the idea that if I finish writing the book, ZooLib will appeal to many more people than it does today, and that will convince the publisher to print the book in, say, 2004.

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