Information Security Conference (ISC 2008) Day 1

The 11th Information Security Confernce (ISC 2008) was held in Teipei, Taiwan. This is a short summary of some presentations I attended.

Marcel Winandy: Property-Based TPM Virtualization

This was actually my presentation. See my older post and my slides

Endre Bangerter: A Demonstrative Ad Hoc Attestation System

The proposal is to use a trusted device for ad hoc attestation of computing platforms, i.e., showing to the user "PC is ok" or "PC is not ok". It is a server-based approach, where the server sends remote procedure call (RPC) to the PC, and the PC displays flickering barcods on the screen. The trusted device is hold in front of the screen and receives the RPC, i.e., decodes the barcode. Finally, the device displays whether PC is OK nor not.

The decision the device displays is actually based on a remote attestation done between the server and the PC. The trusted device is just used as local "trusted display" of the remote server. For each attestation, the flickering barcode will be different (i.e., includes a counter value) to prevent simple replay attacks. (slides)

Hans Löhr: Property-Based Attestation without a Trusted Third Party

This is an improved protocol for property-based attestation. Instead of having a Trusted Third Party (TTP) issuing certificates for properties, the verifier has a-priori a list of configurations. The attestee creates a proof that its configuration is within a defined list of configurations, without revealing which exact configuration it has. The proof is based on group signatures (ring signature scheme) without revealing the secret key used to sign the commitment. (slides)

Xuhua Ding: An Efficient PIR Construction Using Trusted Hardware

Paper about private information retrieval. Improves reshuffeling of database form O(n) to O(sqrt(n)). Records are colored black and white. On each query, they fetch two records of different colors. Retrieved records are colored black. Shuffeling is done only on black ("touched") records. (slides)

Charalampos Papamanthou: Athos - Efficient Authentication of Outsourced File Systems

Outsourced filesystems means they are stored on a server. The server is completely untrusted (i.e., there is no trusted hardware on the server side). Accessing the files are queries to the server, and accompanied by a "proof" of authenticity, both for file system content and hierarchy. This proof is based on cryptographic hashing, and uses authenticated skip lists and authenticated dynamic trees. It is an efficient scheme (similar to Merkle hash trees), the client only has to maintain a O(1) trusted storage. Query operations have O(k log n) time. (slides)

Property-Based TPM Virtualization

This is the title of paper I have written together with Ahmad-Reza Sadeghi and Christian Stüble. We will present it at the 11th Information Security Conference (ISC 2008) in Taipei, Taiwan. I will also give a presentation about it at the HGI Seminar at Ruhr-University Bochum on 10th July 2008.

Virtualization and hypervisors enable useful and cost-efficient means to manage IT infrastructure, especially migration of virtual machines (VMs) between hardware platforms. A challenge in this context is the virtualization of
hardware security modules like the Trusted Platform Module (TPM) since the intended purpose of TPMs is to securely link software and the underlying hardware. Existing solutions for TPM virtualization, however, have various
shortcomings that hinder the deployment to a wide range of useful scenarios. In our paper, we address these shortcomings by presenting a flexible and privacy-preserving design of a virtual TPM that in contrast to existing
solutions supports different approaches for measuring the platform's state and for key generation, and uses property-based attestation mechanisms to support software updates and VM migration. Our solution improves the maintainability and applicability of hypervisors supporting hardware security modules like the TPM. The following figure shows the design.

For each VM that needs a vTPM, there is a separate vTPM instance. We assume the underlying hypervisor to protect the internal state and operations of each vTPM from any unauthorized access. The main building blocks of our vTPM are the following: PropertyManagement represents the virtual PCRs and manages different mechanisms to store and read measurement values; KeyManagement is responsible for creating and loading keys; vTPMPolicy holds the user-defined policy of the vTPM instance, defining which properties are going to be revealed during an attestation operation; CryptographicFunctions provide monotonic counters, random number generation, hashing, etc.; MigrationController is responsible for migrating the vTPM to another platform.

To improve flexible migration and to preserve the availability of sealed data after migration or software updates, an essential step is to support other measurement strategies. Applying property-based measurement and attestation to a vTPM allows much more flexibility in the choice of the hypervisor and for easier updates of applications -- a VM can still use sealed data or run attestation procedures if the properties of the programs remain the same.

Our vTPM design is based on a plug-in-like architecture for various vPCR extension strategies. Each extension strategy is realized by a PropertyProvider module implementing different translation functions. A translation function translates measurements (i.e., hash values of program binaries) into property representations. Each PropertyProvider has its own vector of virtual PCRs. Thus there is a matrix of vPCR values for each vTPM. This allows us to choose, according to the vTPM policy, which PropertyProvider to use on particular sealing or attestation operations.

Depending on the implementation of the PropertyProvider, we can realize property-based sealing and property-based attestation without any change to the interface of the vTPM from the perspective of the associated VM. This enables the availability of protected data and cryptographic keys of the vTPM after migrating to another platform that provides the same security properties but may have a different binary implementation. TPM-enabled applications executed in a VM can directly profit from this flexibility without the need for modification.

[Slides]

Tools for Maintaining a Personal Research Journal

To keep a journal of research activities, especially when studying for a PhD, is generally considered a good idea (see for example desJardins' guide How to Succeed in Graduate School). Such a journal helps to organize ideas, to record the progress of research, and to leverage building new ideas. On the web, you can find also other guidelines which give more examples what to include in the journal, e.g., Notes on the Personal Research Notebook / Journal.

While I used such a journal concept intuitively during my diploma thesis, I wrote it on separate sheets of papers which I transformed later into the written thesis. This worked out very well at that time and on that project. However, now I want to use a tool which can automate those time-consuming things like searching and copy&paste. Today, I have several subprojects and small parts which are sometimes (at least at the beginning) very unrelated. Using a paper notebook as a journal would not be very efficient. So, I wondered which software tools would work out as a research journal for a PhD.
I have tried out several tools, starting from simple text files to journal and todo list functions in KDE Kontact. But the information is still scattered throughout several files on my disk in several different formats (text files, LaTeX files, OpenOffice files, pictures, etc.). I need something that can combine everything and provides a fast search and kind of sorting function (like tagging in Web 2.0 applications).

Finally, I have found two applications which are suiteable for this task: Journler for Mac OS X. This is exactly what I needed. You can enter journal entries in chronological order, add tags, pictures, URLs, PDFs, whatever. When you click on a tag, Journler automatically shows up a list of all entries with this tag. And of course, it makes use of the fast search engines of Leopard to quickly scan your entries for keywords. This is great!

Unfortunately, I have to work on a PC laptop at work. So I can't use Journler there. But I have something similar: BasKet Note Pads for KDE on Linux. It has similar functionalities, and I have started to use it. One good feature I noticed: you can import notes from KNotes and simple text files (now it pays back to have used text files!*g*).

RapidWeaver and RapidBlog

I have begun to use RapidWeaver as web development tool. Although it is only available for Mac, I did not find any similar tool for Linux or even Windows. RapidWeaver works and looks like iWeb, the Apple web-site tool in the iLife package. It is very easy to create a web site with navigation bar, blog, picture gallery, etc. It supports themes, which are actually stylesheet packages including background images and the like.

RapidWeaver also supports Add-on. There is one interesting add-on I have found: RapidBlog. This add-on extends the blogging module of RapidWeaver with synchronization of a Google Blogger (Blogspot) account. This is very nice since it allows you to write your blog posts online on any web browser and system, using the Blogger web interface. But you can still write and manage your posts in the RapidWeaver application.

Now, there is one interesting question: Does RapidBlog automatically synchronize the Blog when you write a new post on the Google Blogger web interface or do you need to run the sync within RapidWeaver manually?

Update: Yeah, this works automatically! Thanks to the PHP script, this site automatically includes the latest posts from the original Blogspot site.

Holisticly provide access

“Bonjour: Holisticly provide access to ethical communities vis-a-vis client-focused.”

Funny description of network technology. This was posted on the Apple website announcing the new Mac OS X Leopard. But they have changed the text now… :-)

See also:
Martin Pittenauer’s blog or the various links you can find using the Internet search engine of your choice.

Compartmented Security for Browsers - Or How to Thwart a Phisher with Trusted Computing

This is the title of a paper written by Sebastian Gajek, Ahmad-Reza Sadeghi, Christian Stüble, and me. We already presented and published it at the Second International Conference for Availability, Reliability and Security (ARES 2007). It is an improved version of the paper “Towards Multicolored Computing”, which I previously announced here. Our approach is based on the ideas of compartmentalization (for isolating applications of different trust level) and a trusted wallet (for storing credentials and authenticating sensitive services on behalf of the user). However, we do not rely on a trusted browser this time. The following figure shows our basic architecture.


In this paper, we show that the wallet can handle the whole authentication process mutually after it has been setup by the user once. We also improved the setup procedure by cryptographically embedding a web site-bounded random value into the account password. This value is unknown to the user. On the one hand, we prevent that the user applies low-entropy passwords to set up an account. On the other hand, we ensure that the user does not use the same password for different accounts.

To realize a transparent usage and in order to provide a safe environment during the account setup, the wallet also works as a network proxy. Hence, the wallet must be capable to parse HTML web sites and to react accordingly, e.g., by initiating the setup procedure.

To protect the confidentiality of the user’s credentials, we use the sealing functionality of a Trusted Platform Module (TPM): We bind the secret data to the integrity measurements of the wallet and the underlying security kernel. This means, the credentials are encrypted using a key that never leaves the TPM, and the decryption is only possible if the same measurement values are logged into the TPM during the boot process as they were taken at encryption time.

More information [Technical Report] [Slides]

CeBIT 2007

On Saturday I took my annual trip to Hannover to visit the CeBIT trade fair. I just want to give my impressions what I have found to be interesting there.

Plasma TVs can have lower power consumption than LCD TVs

This is quite interesting since people still believe Plasma TVs have a high power consumption. However, in contrast to LCD TVs, which always have a constant power consumption (about 160-240 W, depending on the model), Plasma TVs can very in their consumption depending on the current image to display. If the image is very bright, e.g., a white screen or a snow landscape, Plasma TVs have a high power consumption (let’s say 200 W, depending on the model of course). But if the image is dark, e.g. black screen or a night scene in a movie, Plasma TVs consume very less than their maximum consumption (e.g., 60 W only). So, depending on your TV watching habits, a Plasma TV might even save energy compared to a LCD TV!

Mobile phones for older people become more usable and cheaper

I discovered a mobile phone which was especially designed for older people. The “emporiaLife” phone has larger buttons than usual phones, a large display that shows the dialed numbers much bigger, and a special emergency button, which you only have to press to get connected to a number you have previously defined (there can be up to five different emergency numbers). The device is dual-band, can send and receive SMS, and has included a flashlight. At the booth they told me the price will be about 200 Euros.

Car navigation devices get more functionality

There seems to be the trend to integrate a variety of functionality into car (or mobile) navigation devices. I have seen the integration of DVB-T TV or Bluetooth connection to mobile phones at several vendors. One example is Naviflash. Some interesting detail I have also discovered: Naviflash has a flexible bracket with some kind of “ground support” to stabilize the device when attached at the windshield.

Digital picture frames

A lot of vendors now offer digital picture frames, for instance Samsung and its SPF-07N. A digital picture frame displays a digital photo, similar as a normal “hard-cover” picture frame. But a digital picture frame can store several pictures and display them alternately, e.g., changing them periodically or at command. This might become a new big trend; at least if prices are acceptable.

“I’ll call you by trousers”

In the Future Parc, they showed (amongst others) smart textiles. These are clothes which integrate some digital functionality, usually control panels for electronic devices. Funny example: leather trousers with a control panel for a mobile phone. :-)