FYI.  As I understand it, TI calculator boot ROMs use a 512 bit RSA
public key to check the signature of the software they're loading.
When hobbyists who wanted to run their own alternative OS software on
their calculator calculated the corresponding private key and were
thus able to sign their own software, TI sent them DMCA takedowns
claiming they had cracked TI's DRM.  As with the CSS keys, a
publish/takedown chase ensued.  Wikileaks has had the censored keys up
since August.  EFF is now representing the hobbyists, and may stand to
collect legal fees from TI.  Here's Schneier's take:


Electronic Frontier Foundation Media Release

For Immediate Release: Tuesday, October 13, 2009


Jennifer Stisa Granick
   Civil Liberties Director
   Electronic Frontier Foundation
   +1 415 436-9333 x134

EFF Warns Texas Instruments to Stop Harassing Calculator

Baseless Legal Threats Squash Free Speech, Innovation

San Francisco - The Electronic Frontier Foundation (EFF)
warned Texas Instruments (TI) today not to pursue its
baseless legal threats against calculator hobbyists who
blogged about potential modifications to the company's
programmable graphing calculators.

TI's calculators perform a "signature check" that allows
only approved operating systems to be loaded onto the
hardware.  But researchers were able to reverse-engineer
signing keys, allowing tinkers to install custom operating
systems and unlock new functionality in the calculators'
hardware.  In response to this discovery, TI unleashed a
torrent of demand letters claiming that the
anti-circumvention provisions of the Digital Millennium
Copyright Act (DMCA) required the hobbyists to take down
commentary about and links to the keys.  EFF represents
three men who received such letters.

"The DMCA should not be abused to censor online discussion
by people who are behaving perfectly legally," said Tom
Cross, who blogs at "It's legal to engage
in reverse engineering, and its legal to talk about reverse

In fact, the DMCA explicitly allows reverse
engineering to create interoperable custom software like
the programs the hobbyists are using.  Additionally, TI
makes its software freely available on its website, so
there is no connection between the use of the keys and
unauthorized distribution of the code.

"This is not about copyright infringement.  This is about
running your own software on your own device -- a
calculator you legally bought," said EFF Civil Liberties
Director Jennifer Granick.  "Yet TI still issued empty
legal threats in an attempt to shut down discussion of this
legitimate tinkering.  Hobbyists are taking their own tools
and making them better, in the best tradition of American

For the full letters sent to Texas Instruments by EFF on
behalf of their clients:

For this release:

About EFF

The Electronic Frontier Foundation is the leading civil
liberties organization working to protect rights in the
digital world. Founded in 1990, EFF actively encourages and
challenges industry and government to support free
expression and privacy online. EFF is a member-supported
organization and maintains one of the most linked-to
websites in the world at


The Cryptography Mailing List
Unsubscribe by sending "unsubscribe cryptography" to

Reply via email to