[Noisebridge-discuss] File format specification

Jacob Appelbaum jacob at appelbaum.net
Fri Mar 19 00:21:50 UTC 2010


Hi,

I'm working on a new file format for magnetic stripe information. I'm
calling it MagPack. There are many dirty hacks but I don't believe there
are any actual open standards. If someone knows otherwise, I'd be happy
to be corrected!

Here is an introduction to some of the details and ideas:
http://code.google.com/p/libmsr/source/browse/trunk/README.file-specification

The next step is to define a structure for captured data and for
relevant meta-data. I'm starting to ponder the actual format of the data
on disk. There are many options (please not xml!) but it's unclear on
what is the most cross platform, least external library dependent, easy
to use, easy to protect, easy to compress, etc.

There are a variable number of elements for a given captured signal.
Assuming that a user has a simple ISO formatted magnetic stripe, it's
quite simple to store it as a byte array. It is important to include
meta-data about the capture (date, time, reader, host OS platform, etc)
in any MagPack file. It's also important to allow repacking, re-encoding
and other stuff. I'd like to be able to encrypt a MagPack file, so the
contents should probably be properly encapsulated...

The data captured is entirely arbitrary. It may contain any byte
sequence. It will certainly contain binary information (from raw bit
patterned reads), it will possibly have blobs of images (png, bmp, etc),
it will hopefully have UTF-8 strings for any field related to the
meta-data...

What's a reasonable way to accomplish this? Should I just stick with the
simple "bunch of files in a folder, tar, gzip, possibly encrypt" method?
Should I get fancy and use XML, possibly encrypting the .xml file with
an unencrypted header?

In an ideal world, I'd like to do it entirely in pure C and in a
portable manner. This tends to push me away from XML and then there's
XML that pushes me away from XML. But is a custom binary format better?
Isn't that why XML was invented? To solve just this problem?

Best,
Jake

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 155 bytes
Desc: OpenPGP digital signature
URL: <http://www.noisebridge.net/pipermail/noisebridge-discuss/attachments/20100318/07884303/attachment-0002.sig>


More information about the Noisebridge-discuss mailing list