XLDB Tutorial

Michael Bender and I presented a tutorial on Data Structures and Algorithms for Big Databases at XLDB 2012.

How to digitally sign a pdf file using free software in GNU/Linux

I recently needed to sign a pdf document for legal purposes. The other party was willing to accept a digital signature. That does not mean copying an picture onto a pdf document. It's using public key crypto to sign the pdf document. Acrobat can do it, but I use free software, so, after about 30 minutes I figured out how to do it.

1. I extracted my csail certificate from my browser. In firefox
   • edit->preferences->advanced->encryption->view certificates
   • select the certificate
   • then hit backup
   • save it as a pkcs12 file
   • you'll be asked for a password for the backup. You'll use this later.
2. I got jsignpdf-1.3.0 and installed it
   • $ unzip JSignPdf-1.3.0.zip
   • $ cd jsignpdf-1.3.0
3. I ran it: $ java -jar JSignPdf.jar
   • A simple window popped up with some forms to fill in.
     • keystore type: PKCS12
     • keystore file: choose the backup made of the certificate
     • keystore password: the password you used
     • input file: the pdf file to sign
     • output file: I chose another name to avoid overwriting something useful
     • I clicked the checkbox on "visible signature"
     • Went to the "settings" box next to 'visible signature"
     • I chose the page where the signature needed to be placed, and I chose coordinates. I found the coordinates by running gv input.pdf since ghostview shows the coordinates in the upper left corner. For example, I put my signature on page 7 and put signature at coordinates
       • 147
       • 482
       • 369
       • 519
     • I chose Display: "Signature name and decsription"
     • Hit "close"
   • Then "sign it" on the original jpdfsign window.

my webpages are mostly back

After being down for nearly a year my web content at bradley.csail.mit.edu is mostly back up at http://people.csail.mit.edu/bradley/.

There remain a few things missing...

MIT Academic Calendar

I created a google calendar for the MIT Academic Calendar. The calendar ID is gtfme9paltu2dfdac81f0p73us@group.calendar.google.com.

If you would like to volunteer to help maintain this calendar, please contact bradley@mit.edu. Originally I was using obpoblff7vffces4ot4g73b02g@group.calendar.google.com, but it's not being maintained, and I don't know how to contact the maintainers.

planetsupertech

I've created planet supertech to aggregate supertech-related blogs.

Fedora 10 on x61s

Recent Fedora 10 updates destabilized my Thinkpad x61s. (Mouse movement would start getting sluggish and eventually the system would freeze.) It's probably something to do with dri in the xserver (and I don't even know what that means :-) I put this into my ~/.drirc, and my machine has been fine. I think the key is vblank_mode.

<driconf>
    <device screen="0" driver="i965">
        <application name="Default">
            <option name="force_s3tc_enable" value="false" />
            <option name="no_rast" value="false" />
            <option name="fthrottle_mode" value="2" />
            <option name="bo_reuse" value="1" />
            <option name="vblank_mode" value="0" />
            <option name="allow_large_textures" value="2" />
        </application>
    </device>
</driconf>

tabook resurfaces

Lenovo moved the thinkpad tabook.pdf to
http://www.lenovo.com/psref/pdf/tabook.pdf
and google has a hard time finding it. The old ftp site run by IBM isn't working anymore.