Category: 28C3 (page 1 of 2)

Recordings of 28C3 talks available

The 28th Chaos Communication Congress ended yesterday and most of the talks are already available for download.

Credit goes to the FEM, who did a really tremendous job streaming the talks during the conference and who still continue their hard work by publishing the Official Releases of the last talks.

Did you really love certain events? Weren’t so excited about others? Let us know! You can leave feedback via the Fahrplan. Find the events you’d like to leave your thoughts on and click on the green “Give Feedback” link in the lower right hand corner. We use this information to plan future events, so your input is essential.

Many thanks again for a great Congress and we’ll see you at the Sigint 2012 in May or the next Chaos Communication Congress!

Crypto talk at 28C3: Sovereign Keys – A proposal for fixing attacks on CAs and DNSSEC, Day 3, 23:00, Saal 3

After many attacks on X.509 and the internet PKI infrastructure, it became clear, that the current state does not meet the requirements for the upcoming challenges for secure internet communication in the future. CAs have been completely compromised, and weak cryptography used by PKIs has been broken in practice to issue rouge certificates. So there is a need for an alternative how to establish a binding between your public key and your identity. The EFF will present their proposal to improve the security of SSL/TLS connections this evening at the congress.

See the talk, Day 3, 23:00, Saal 3.

Author: Erik Tews

Crypto talk at 28C3: TRESOR: Festplatten sicher verschlüsseln, Day 3, 14:30, Saal 2

Some of you may remember the Cold Boot Attack. It’s a general method, how almost all disk encryption schemes on PCs and Laptop can be circumvented. Usually, when a harddisk or just a partition is encrypted, the encryption software used, needs to store the keys in memory, as long as the filesystem is mounted. Three years ago, it was shown that this key can be extracted, just by removing the RAM module, and dumping it’s content on a second PC using a custom software. Alternatively, the system can be booted from a CD or USB-stick with a custom software, that dumps the content of the RAM. As long as the RAM has only been off for a few seconds, or cold down to a low temperature, it doesn’t loose the stored data completely, and the encryption keys can be recovered from that dump.

Today, a solution  for this problem will be presented, that prevents the attack by never storing the encryption key in RAM. Instead, CPU registers are used, and because the encryption code runs in kernel space, it can ensure, that they are never stored in RAM.

This sounds like a good solution to me, except that it only prevents the encryption key from leaking. Of course, the actual data, that is decrypted and that applications on that system work with, can still be found in RAM, but I have no idea how this can be fixed easily.

See the talk: Day 3, 14:30, Saal 2

Crypto talk at 28C3: Bitcoin

Two Bitcoin related talks will be presented tomorrow. Bitcoin is a decentralized digital currency, and of course uses various cryptographic schemes as building blocks. Because Bitcoins can be exchanged with real money, Bitcoin is more than just an academic playground and real cash could be lost, if an attack on Bitcoin would be found.

The first talk Bitcoin – An Analysis will be presented by Kay Hamacher and Stefan Katzenbeisser. From the abstract:

In this presentation, we show results on network analysis of the money flow, the behavior of individuals, and the overall scalability of P2P-currencies. At the same time we will discuss advanced “financial instruments” that one might find in the transactions.

So I assume that this will be an in-depth analysis of the current state of the Bitcoin network. The second talk Electronic money: The road to Bitcoin and a glimpse forward – How the e-money systems can be made better given by peio will cover the general topic of digital money and what lead to the development of Bitcoin. It will even look beyond Bitcoin and what can be improved in the future. From the abstract:

The proposed talk provides a definition of the problem of creating e-money and after a review of the state of the art points out possible solutions and proposes questions for discussion for the properties of electronic money system.

For me, both talks are interesting. Besides the cryptographic challenges in this research area, this topic also has an heavy political impact. What would you do, if you could exchange money over the internet, untraceable and anonymously?

See the talks, Day 3, 14:00 Saal 1, and Day 3, 17:15, Saal 3.

Crypto talk at 28C3: Time is on my Side – Exploiting Timing Side Channel Vulnerabilities on the Web, Day 2, 18:30, Saal 2

Side channel attacks are very well known in cryptography. In a nutshell, a side channel information (not the ciphertext or the public key) is used to recover a secret. This can be the time it takes for a cryptographic operation, the power consumption of a device, the variations in the electromagnetic field surrounding a device or just the acoustic noise produced by a device. Secure implementations of cryptographic schemes usually implement countermeasures against these kind of attacks.

In contrast to the cryptography world, side channel attacks are not very well known in the general IT security business. However, side channel attacks can also be used against applications, that don’t use cryptography, but process any kind of secret data. Examples could be the size of a database, the privileges of a user, or just the length of a stored password. Sebastian Schinzel will present his analysis, as well as general attack techniques, than can be used to exploit side channel weaknesses on the web.

I think this talk is important, because it raises the general awareness of side channel attacks to the general IT security community. Side channel attacks are not solely restricted to cryptographic algorithms, and can be used as an effective attack against many more applications.

See the talk, Day 2, 18:30, Saal 2

Author: Erik Tews

Crypto Talk at 28C3: Ein Mittelsmannangriff auf ein digitales Signiergerät, Day 2, 18:30, Saal 3

Alexander Koch will be presenting the results of his bachelor thesis at 28C3. In his thesis, he implemented a person-in-the-middle-attack (don’t call it man-in-the-middle attack) against a USB chipcard reader for digital signatures. Instead of modifying  the software on the users PC, he implemented a USB hardware device, that can be plugged in between the chip card reader and the host PC. Because the device behaves passively as long as no signature is made, it is hard to detect from any kind of security software from the PC side. When a signature is made, the device can transmit a different message digest (another document is signed) to the chipcard reader. The generated signature is stored and can later be retrieved from the attacker using a wireless link.

I think this is a good demonstration that shows, why digital signature made on (secure) devices, that cannot display the signed document are not a good idea. Also, a hardware device is hard to detect in software, because it acts like a valid chip card reader to the PC.

See the talk, Day 2, 18:30, Saal 3

Author: Erik Tews

Crypto Talk at 28C3: Effective Denial of Service attacks against web application platforms, Day 2, 14:00, Saal 1

Julian Wälde and Alexander Klink will be presenting a new attack against Web Application Frameworks (WAF), that can be used to generate HTTP requests, that take several minutes of CPU time to process. Sending many of these requests in parallel can be used as an effective Denial of Service attack against many websites. Even one cannot spot any relation to cryptography from the abstract, I have been informed that this talk will also cover many cryptography related aspects.

See the talk, Day 2, 14:00, Saal 1

Author: Erik Tews

Live translation into English at 28C3

A group of enthusiast interpreters at the congress are organizing simultaneous translation into English for a small selection of German talks. We are aiming for the “fun” events that have been translated for a few years, and for the first time this year, we are trying our hand at some “content” talks as well.

The provisional list of translated events is:

Be sure to tell your English speaking friends to check out some really great content they might not otherwise have access to!

Call for live interpreters at 28C3

We, Sebastian and Julian, are part of last year’s core team of live interpreters. In the past we have translated at several Chaos Communication Congresses, together with Volty who cannot be there this year and many others.
We want to continue this tradition of translating important talks such as the Fnord News Show and the Hacker Jeopardy, but also others, depending on our resources.
If you are interested in helping out, please meet us on Day 1, December 27th, at 21:00 in the angel area down in the basement. You may also contact us via e-mail at Sebastian.Lisken _at_ or julian _at_ – or via twitter at @hdsjulian.

The talks we want to interpret are:

Now, as we have gathered some experience in the past few years, we would like to intensify our efforts and get even more important German talks to be translated even better.
Therefore we need help from fellow hackers. Please note that the following rules might sound a little strict for a voluntary job. However, experiences from the last years have shown that this work can only be done if there is absolutely no personal vanity involved and everybody is willing to submit to a strong hierarchy in order to do a good job. Nobody wants to get bored with a bad translation and we are truly willing to give our best. Also the work in the interpretation booth can be very, very stressful at times.
We want to provide all congress attendees (and people watching the stream) the best possible translation. In order to do this we are willing to work hard and submit ourself to a strict set of rules. We expect the same from everybody who wants to help us.

You are:
– Excellent in speaking English and German
– Or excellent in understanding English and German, with a talent for keeping your head up in stressful situations
– Willing to submit to a strong set of rules
– Possibly experienced with translations

Jobs to be done:


We need some good translators willing to spend part of their time at the Congress in the speaker’s cabin. You will sit together with two other translators and do your best interpreting talks live in several minute long segments as told to you by the director.


We also need some very few “Directors”. In the past we have noticed that we get into the best flow if we have a person listening to our translations and deciding on the fly who should do the talking. This director will have to have a good understanding of the work the interpreters are doing. They will decide autonomously when to choose which interpreter for how long. Their job is to get a good flow into the translation and prevent exhaustion and lack of concentration among the interpreters.

The director can be an interpreter as well. When they choose to act as interpreter, the director will put a replacement director in charge for the duration of that segment.


Please do not feel insulted by the strictness of these rules. We have had issues in the past with the vanity of individuals who didnt do a good job but insisted to continue interpreting. We want to prevent this.

1. During the talk, the core team’s word is law.
2. The core team at first consists of Sebastian and Julian. We will be eager to invite more people as we move along. We strongly believe in a trust and merit based system.
3. There will be no discussions in the interpretation booth. Period.
4. Disputes will be solved outside and _after_ the talks.
5. We do understand that interpreting is a skill to be learned through practice. We will not send away newbies. We will however make sure their talking time is limited until they feel secure and able to do more segments.
6. After the talk we will have a discussion with all participants. There will be open criticism and everybody will have the right to speak their mind. This includes criticising the core team (who will also be interpreting and directing, of course) as well as the other directors and interpreters for their work as well as their behaviour. Of course this round is also open for positive criticism and finding out what was good.

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