Marcel Fernandez

Mobile Agent Watermarking and Fingerprinting: Tracing Malicious Hosts

Mobile agents are software entities consisting of code and data that can migrate autonomously from host to host executing their code. Despite its benefits, security issues strongly restrict the use of code mobility. The protection of mobile agents against the attacks of malicious hosts is considered the most difficult security problem to solve in mobile agent systems.

Fingerprinting Concatenated Codes with Efficient Identification

A fingerprinting code is a set of codewords that are embedded in each copy of a digital object, with the purpose of making each copy unique. If the fingerprinting code is c-secure, then the decoding of a pirate word created by a coalition of at most c dishonest users, will expose at least one of the guilty parties. In this paper we construct a 2-secure fingerprinting code by concatenating an inner (2,2)-separating code with an outter IPP code. The particular choice of the codes is such that allows the use of efficient decoding algorithms that correct errors beyond the error correction bound of the code, namely a simplified version of the Chase algorithms for the inner code and the Koetter-Vardy soft-decision list decoding algorithm for the outter code.

Soft-decision tracing in fingerprinted multimedia content

To protect intellectual property and distribution rights against dishonest customers in the multimedia content market, fingerprinting schemes that use error-correcting codes help identify users illegally redistributing media. This article presents a traitor-tracing algorithm that takes advantage of soft-decision decoding techniques to find all identifiable traitors.

A family of collusion 2-secure codes

We present systematic strategy for collusions attacking a fingerprinting scheme. As a particular case, this strategy shows that linear codes are not good fingerprinting codes. Based on equidistant codes, we construct a family of fingerprinting codes in which the identification of guilty users can be efficiently done using minimum distance decoding.

Boneh-Shaw fingerprinting and soft decision decoding

Collusion-secure codes are used for digital fingerprinting and for traitor tracing. In both cases, the goal is to prevent unauthorised copying of copyrighted material, by tracing at least one guilty user when illegal copies appear. The most well-known collusion-secure code is due to Boneh and Shaw (1995/98). In this paper we improve the decoding algorithm by using soft output from the inner decoder, and we show that this permits using significantly shorter codewords.

Protecting mobile agents by using traceability techniques

Mobile agents are software entities consisting of code and data that can migrate autonomously from host to host executing their code. Despite its benefits, security issues strongly restrict the use of code mobility. The protection of mobile agents against the attacks of malicious hosts is considered the most difficult security problem to solve in mobile agent systems. The approach that is presented detects manipulation attacks performed during the agents execution. This approach also traces the malicious hosts responsible for the manipulation attacks. Software watermarking techniques are used in order to embed a mark into the agent. The agents execution creates marked results. When the agent returns to the origin host, these results are examined in order to find the embedded mark. If the mark has changed, this means that the executing host has modified the agent.

Almost separating and almost secure frameproof codes

The theory of separating codes has been applied in several areas of science ranging from automata synthesis to the protection of distribution rights. In this paper, we introduce a relaxed version of separating and secure frameproof codes and show that for the relaxed definitions these two notions are different, as opposed to the original definitions when these notions coincide. Moreover, we also discuss how this new relaxed versions of the codes can be used to construct a family of fingerprinting codes.

A Family of Asymptotically Good Binary Fingerprinting Codes

A fingerprinting code is a set of codewords that are embedded in each copy of a digital object with the purpose of making each copy unique. If the fingerprinting code is c-secure with error, then the decoding of a pirate word created by a coalition of at most c dishonest users, will expose at least one of the guilty parties with probability 1-ϵ. The Boneh-Shaw fingerprinting codes are n-secure codes with ϵ_B error, where n also denotes the number of authorized users. Unfortunately, the length the Boneh-Shaw codes should be of order O(n³ log(n/ϵ_B)), which is prohibitive for practical applications. In this paper, we prove that the Boneh-Shaw codes are (c<; n)-secure for lengths of order O(nc² log(n/ϵ_B)). Moreover, in this paper it is also shown how to use these codes to construct binary fingerprinting codes of length L=O(c⁶ log(c/ϵ) log n), with probability of error ϵ<;ϵ_B and an identification algorithm of complexity poly(log n)=poly(L). These results improve in some aspects the best known schemes and with a much more simple construction.

Tracing illegal redistribution using errors-anderasures and side information decoding algorithms

In a fingerprinting scheme, a distributor places marks in each copy of a digital object. Placing different marks in different copies uniquely identifies the recipient of each copy, and therefore allows tracing of the source of an unauthorised redistribution. A widely used approach to the fingerprinting problem is the use of error correcting codes with a suitable large minimum distance. With this approach, the set of embedded marks in a given copy is precisely a code word of the error correcting code. We present two different approaches that use side information for the tracing process. The first approach deals uses the Guruswami–Sudan errors-and-erasures list decoding algorithm whereas the second approach shows the use of a full side information matrix.

Traitor tracing over YouTube video service--proof of concept

The development explained in this article proves that is possible to trace dishonest users who upload videos with sensitive content to the YouTube service. To achieve tracing these traitor users, fingerprint marks are embedded by a watermarking algorithm into each copy of the video before distributing it. Our experiments show that if the watermarking algorithm is carefully configured and the fingerprints are correctly chosen, the traitor, or a member of a set of traitors who have performed a collusion attack, can be found from a pirate video uploaded to the YouTube service.