Entries Tagged "cryptanalysis"

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Class Break of TiVoToGo DRM

Last week I wrote about the security problems of having a secret stored in a device given to your attacker, and how they are vulnerable to class breaks. I singled out DRM systems as being particularly vulnerable to this kind of security problem.

This week we have an example: The DRM in TiVoToGo has been cracked:

An open source command-line utility that converts TiVoToGo movies into an MPEG file and strips the DRM is now available online. Released under a BSD license, the utility—called TiVo File Decoder—builds on the extensive reverse engineering efforts of the TiVo hacking community. The goal of the project is to bring TiVo media viewing capabilities to unsupported platforms like OS X and the open source Linux operating system. TiVoToGo support is currently only available on Windows.

EDITED TO ADD (12/8): I have been told that TiVoTo Go has not been hacked: “The decryption engine has been reverse engineered in cross-platform code – replicating what TiVo already provides customers on the Windows platform (in the form of TiVo Desktop software). Each customer’s unique Media Access Key (MAK) is still needed as a *key* to decrypt content from their particular TiVo unit. I can’t decrypt shows from your TiVo, and you can’t decrypt shows from mine. Until someone figures out how to produce or bypass the required MAK, it hasn’t been cracked.”

And here’s a guide to installing TiVoToGo on your Mac.

EDITED TO ADD (12/17): Log of several hackers working on the problem. Interesting.

Posted on December 7, 2006 at 12:42 PMView Comments

New Timing Attack Against RSA

A new paper describes a timing attack against RSA, one that bypasses existing security measures against these sorts of attacks. The attack described is optimized for the Pentium 4, and is particularly suited for applications like DRM.

Meta moral: If Alice controls the device, and Bob wants to control secrets inside the device, Bob has a very difficult security problem. These “side-channel” attacks—timing, power, radiation, etc.—allow Alice to mount some very devastating attacks against Bob’s secrets.

I’m going to write more about this for Wired next week, but for now you can read the paper, the Slashdot thread, and the essay I wrote in 1998 about side-channel attacks (also this academic paper).

Posted on November 21, 2006 at 7:24 AMView Comments

Notes from the Hash Function Workshop

Last month, NIST hosted the Second Hash Workshop, primarily as a vehicle for discussing a replacement strategy for SHA-1. (I liveblogged NIST’s first Cryptographic Hash Workshop here, here, here, here, and here.)

As I’ve written about before, there are some impressive cryptanalytic results against SHA-1. These attacks are still not practical, and the hash function is still operationally secure, but it makes sense for NIST to start looking at replacement strategies—before these attacks get worse.

The conference covered a wide variety of topics (see the agenda for details) on hash function design, hash function attacks, hash function features, and so on.

Perhaps the most interesting part was a panel discussion called “SHA-256 Today and Maybe Something Else in a Few Years: Effects on Research and Design.” Moderated by Paul Hoffman (VPN Consortium) and Arjen Lenstra (Ecole Polytechnique Federale de Lausanne), the panel consisted of Niels Ferguson (Microsoft), Antoine Joux (Universite de Versailles-Saint-Quentin-en-Yvelines), Bart Preneel (Katholieke Universiteit Leuven), Ron Rivest (MIT), and Adi Shamir (Weismann Institute of Science).

Paul Hoffman has posted a composite set of notes from the panel discussion. If you’re interested in the current state of hash function research, it’s well worth reading.

My opinion is that we need a new hash function, and that a NIST-sponsored contest is a great way to stimulate research in the area. I think we need one function and one function only, because users won’t know how to choose between different functions. (It would be smart to design the function with a couple of parameters that can be easily changed to increase security—increase the number of rounds, for example—but it shouldn’t be a variable that users have to decide whether or not to change.) And I think it needs to be secure in the broadest definitions we can come up with: hash functions are the workhorse of cryptographic protocols, and they’re used in all sorts of places for all sorts of reasons in all sorts of applications. We can’t limit the use of hash functions, so we can’t put one out there that’s only secure if used in a certain way.

Posted on September 11, 2006 at 3:30 PMView Comments

Galileo Satellite Code Cracked

Anyone know more?

Members of Cornell’s Global Positioning System (GPS) Laboratory have cracked the so-called pseudo random number (PRN) codes of Europe’s first global navigation satellite, despite efforts to keep the codes secret. That means free access for consumers who use navigation devices—including handheld receivers and systems installed in vehicles—that need PRNs to listen to satellites.

Security by obscurity: it doesn’t work, and it’s a royal pain to recover when it fails.

Posted on July 11, 2006 at 11:30 AMView Comments

Da Vinci Code Ruling Code

There is a code embedded in the ruling in The Da Vinci Code plagiarism case.

You can find it by searching for the characters in italic and boldface scattered throughout the ruling. The first characters spell out “SMITHCODE”: that’s the name of the judge who wrote the ruling The rest remains unsolved.

According to The Times, the remaining letters are: J, a, e, i, e, x, t, o, s, t, p, s, a, c, g, r, e, a, m, q, w, f, k, a, d, p, m, q, z.

According to The Register, the remaining letters are: j a e i e x t o s t g p s a c g r e a m q w f k a d p m q z v.

According to one of my readers, who says he “may have missed some letters,” it’s: SMITHYCODEJAEIEXTOSTGPSACGREAMQWFKADPMQZV.

I think a bunch of us need to check for ourselves, and then compare notes.

And then we have to start working on solving the thing.

From the BBC:

Although he would not be drawn on his code and its meaning, Mr Justice Smith said he would probably confirm it if someone cracked it, which was “not a difficult thing to do”.

As an aside, I am mentioned in Da Vinci Code. No, really. Page 199 of the American hardcover edition. “Da Vinci had been a cryptography pioneer, Sophie knew, although he was seldom given credit. Sophie’s university instructors, while presenting computer encryption methods for securing data, praised modern cryptologists like Zimmermann and Schneier but failed to mention that it was Leonardo who had invented one of the first rudimentary forms of public key encryption centuries ago.”

That’s right. I am a realistic background detail.

EDITED TO ADD (4/28): The code is broken. Details are in The New York Times:

Among Justice Smith’s hints, he told decoders to look at page 255 in the British paperback edition of “The Da Vinci Code,” where the protagonists discuss the Fibonacci Sequence, a famous numerical series in which each number is the sum of the two preceding ones. Omitting the zero as Dan Brown, “The Da Vinci Code” author, does the series begins 1, 1, 2, 3, 5, 8, 13, 21.

Solving the judge’s code requires repeatedly applying the Fibonacci Sequence, through the number 21, to the apparently random coded letters that appear in boldfaced italics in the text of his ruling: JAEIEXTOSTGPSACGREAMQWFKADPMQZVZ.

For example, the fourth letter of the coded message is I. The fourth number of the Fibonacci Sequence, as used in “The Da Vinci Code,” is 3. Therefore, decoding the I requires an alphabet that starts at the third letter of the regular alphabet, C. I is the ninth letter regularly; the ninth letter of the alphabet starting with C is K; thus, the I in the coded message stands for the letter K.

The judge inserted two twists to confound codebreakers. One is a typographical error: a letter that should have been an H in both the coded message and its translation is instead a T. The other is drawn from “Holy Blood, Holy Grail,” the other book in the copy right case. It concerns the number 2 in the Fibonacci series, which becomes a requirement to count two letters back in the regular alphabet rather than a signal to use an alphabet that begins with B. For instance, the first E in the coded message, which corresponds to a 2 in the Fibonacci series, becomes a C in the answer.

The message reads: “Jackie Fisher who are you Dreadnought.”

I’m disappointed, actually. That was a whopper of a hint, and I would have preferred the judge to keep quiet.

EDITED TO ADD (5/8): Commentary on my name being in The Da Vinci Code.

Posted on April 27, 2006 at 6:47 PMView Comments

The Kryptos Sculpture

The Kryptos Sculpture is located in the center of the CIA Headquarters in Langley, VA. It was designed in 1990, and contains a four-part encrypted puzzle. The first three parts have been solved, but now we’ve learned that the second-part solution was wrong and here’s the corrected solution.

The fourth part remains unsolved. Wired wrote:

Sanborn has said that clues to the last section, which has only 97 letters, are contained in previously deciphered parts. Therefore getting those first three sections correct has been crucial.

Posted on April 21, 2006 at 7:54 AMView Comments

Power Analysis of RFID Tags

This is great work by Yossi Oren and Adi Shamir:

Abstract (Summary)

We show the first power analysis attack on passive RFID tags. Compared to standard power analysis attacks, this attack is unique in that it requires no physical contact with the device under attack. While the specific attack described here requires the attacker to actually transmit data to the tag under attack, the power analysis part itself requires only a receive antenna. This means that a variant of this attack can be devised such that the attacker is completely passive while it is acquiring the data, making the attack very hard to detect. As a proof of concept, we describe a password extraction attack on Class 1 Generation 1 EPC tags operating in the UHF frequency range. The attack presented below lets an adversary discover the kill password of such a tag and, then, disable it. The attack can be readily adapted to finding the access and kill passwords of Gen 2 tags. The main significance of our attack is in its implications ­ any cryptographic functionality built into tags needs to be designed to be resistant to power analysis, and achieving this resistance is an undertaking which has an effect both on the price and on the read range of tags.

My guess of the industry’s response: downplay the results and pretend it’s not a problem.

Posted on March 17, 2006 at 12:22 PMView Comments

Sidebar photo of Bruce Schneier by Joe MacInnis.