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Discussioni Tesi di Dottorato Marengo e Pomponiu
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Academic year 2012/2013
- Course ID
- SEM-DOTT1
- Year
- 1° anno 2° anno 3° anno
- Teaching period
- Seminario
- Type
- Seminario
- Credits/Recognition
- 0
- Course disciplinary sector (SSD)
- INF/01 - informatica
- Delivery
- Tradizionale
- Language
- Italiano
- Attendance
- Facoltativa
- Type of examination
- Non prevista
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Sommario del corso
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Course objectives
ore 12-13: Elisa Marengo
Titolo: 2CL Protocols: Interaction Patterns Specification in Commitment Protocols.
Abstract: Commitment protocols have been deeply investigated in the context
of multiagent systems (MAS) as a valuable way for specifying interaction
and communication protocols. Commitments capture social relations among
the interacting parties, expressing the engagement of a debtor towards a
creditor agent, to do something or to achieve some condition of interest.
By specifying only what agents are expected to do, rather then how they
are expected to satisfy their commitments, this kind of specification is highly
appreciated because it leaves great freedom of behaviour to agents.
However, in many practical contexts there is the need of capturing some
patters that the interaction is desired to respect and that improve coordination.
The contribution of this thesis goes in this direction, by presenting an extension
of commitment protocols which allows one to express a set of desired patterns
given as constraints among facts and commitments. Being the approach
declarative, it still provide a high flexibility to agents. More in detail, the proposal
is to explicitly account for a regulative component of the specification, capturing
the set of constraints on the interaction, and a separate and decoupled constitutive
specification defining the set of actions that can be performed. The advantages
of this decoupling is a greater modularity in the specification which entails an
easier protocol design, re-use and extension. An operational semantics is also
provided. It is obtained as extension of the commitment machine
in such a way to consider the role of constraints in deciding which of the possible
interactions can be considered as legal for the protocol.
The proposal is validated by modelling some real case studies and by
showing the advantages of its adoption with respect to other proposals from
the literature. In order to support the design and the analysis of protocol
specifications, a tool offering different kinds of functionalities is presented.
Among these, a prolog program allows for the generation of the labelled
graph of the possible interactions, where labels are used to represent constraints
or commitments violations.
ore 13-14: Victor Pomponiu
Titolo: The Use of Singular Value Decomposition in Information Hiding
Abstract: In recent years, the necessity to protect multimedia content from
illegal copying has been made more critical by the advent of digital technology.
A common and well-discussed solution to counter the unauthorized distribution
of copyrighted contents is applied by means of digital watermarking. This term
refers to specific information hiding techniques whose purpose is to embed secret
information inside multimedia contents, such as images, video or audio streams.
The watermark, i.e., the signal added to digital media, can be detected and retrieved
when necessary. In the specific field of content protection, the objective is to identify
the media’s owner by means of a specific user-related watermark.
In the last years the well-known numerical tool called Singular Value Decomposition (SVD)
received much attention from the watermarking community. However, few of these
schemes take into consideration another crucial constraint, the security, which
guarantees the usability of the watermarking technology. This dissertation focuses on
the security of digital watermarking applications that make use of SVD transform to
convey the watermark information.
First, we analyze and quantify the security of the watermarking schemes based on SVD
that embed the watermark additively of through quantization. These schemes are insecure
and cannot be used for applications that require ownership protection and authentication.
This is due to the fact that the space where the watermark resides, i.e., the embedding
space, can be estimated and the watermark removed or overwritten. To motivate our
findings we devise two novel attacks that remove the watermark while minimizing the
perceptual distortion.
To cope with these attacks we explore the use of the singular vectors for information
hiding. In particular, the proposed watermarking algorithm, that outperforms previously
proposed image watermarking methods, inserts the watermark by modifying the angles
formed by the singular vectors.
Suggested readings and bibliography
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Class schedule
Days Time Classroom Venerdì 12:00 - 14:00 Sala Riunioni Dipartimento di Informatica Lessons: dal 19/10/2012 to 19/10/2012
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Note
La commissione sarà formata da:
Prof.ssa Carla Simone (Università degli Studi di Milano-Bicocca)
Prof. Enrico Magli (Politecnico di Torino)
Dr. Paolo Torroni (Università di Bologna)
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