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We build on this result to offer the first *identity-based* aggregate signature scheme that admits unrestricted aggregation. In our construction, an arbitrary-sized set of signatures on identity/message pairs can be aggregated into a single group element, which authenticates the entire set. The identity-based setting has important advantages over regular aggregate signatures in that it eliminates the considerable burden of having to store, retrieve or verify a set of verification keys, and minimizes the total cryptographic overhead that must be attached to a set of signer/message pairs. While identity-based signatures are trivial to achieve, their aggregate counterparts are not. To the best of our knowledge, no prior candidate for realizing unrestricted identity-based aggregate signatures exists in either the standard or random oracle models.
A key technical idea underlying these results is the realization of a hash function with a Naor-Reingold-type structure that is publicly computable using repeated application of the multilinear map. We present our results in a generic ``leveled\'\' multilinear map setting and then show how they can be translated to the GGH graded algebras analogue of multilinear maps.
an ISO standard and an RFC. Moreover, MISTY1 was selected to be the blueprint on top of which KASUMI, the GSM/3G block cipher, was based. Since its introduction, and especially in recent years, MISTY1 was subjected to extensive cryptanalytic efforts, which resulted in numerous attacks on its reduced variants. Most of these attacks aimed at maximizing the number of attacked rounds, and as a result, their complexities are highly impractical.
In this paper we pursue another direction, by focusing on attacks with a practical time complexity. The best previously-known attacks with practical complexity against MISTY1 could break either 4 rounds (out of 8), or 5 rounds in a modified variant in which some of the FL functions are removed. We present an attack on 5-round MISTY1 with all the FL functions present whose time complexity is 2^38 encryptions. When the FL functions are removed, we present a devastating (and experimentally verified) related-key attack on the full 8-round variant, requiring only 2^18 data and time.
While our attacks clearly do not compromise the security of the full
MISTY1, they expose several weaknesses in MISTY1\'s components, and
improve our understanding of its security. Moreover, future designs which rely on MISTY1 as their base, should take these issues into close consideration.
We are looking for people with advanced knowledge and special skills in at least three of the following areas:
- Network and System Security
- Privacy-Enhancing Technologies and data protection
- Identity Management
- Mobile Platforms, Smartcards and Trusted Computing
- Mobile Application Development (e.g. in Android, etc.)
- Programming languages and experiences in software projects
- Administration skills in different platforms (e.g. UNIX, Linux, Windows)
- Web technologies and development
- Project management
The position is available immediately and has a fixed-term of 3 years with an extension option.
Deadline for applications: 2013-07-31
Contact for applications: Prof. Dr. Kai Rannenberg, bewerbungen(at)m-chair(dot)net
Documents recommended to be submitted: personal statement of purpose, current resume, official references, list of publications, official test scores
More Information: http://www.m-chair.net/wps/wse/home/rannenberg/career/
Applications should be submitted electronically to https://secure.interfolio.com/apply/21679 and include (1) a cover letter describing academic qualifications and experience for this position, (2) a statement of the candidate’s research program, (3) a list of publications, (4) a description of teaching philosophy, including a list of courses the candidate is qualified to teach, (5) evidence of teaching effectiveness, (6) a curriculum vitae, and (7) at least three letters of reference. Screening of applications will begin on October 15, 2013, and will continue until the positions are filled. Salary is competitive and will be commensurate with experience and qualifications.
The candidates will work on the following topics:
Thesis 1 - Faut and side-channel attacks.
Thesis 2 - Formal proofs of hardware and software implementations.
Thesis 3 - Lightweight cryptography (theory and practice).
Thesis 4 - Embedded equipment securit.
Due to employment visa constraints, the candidates must be of EU citizenship or Swiss.
The candidate will be based in the Paris area with access to very advanced laboratory equipment.
We search for a candidate with a strong background in practical system level security. The candidate is expected to support supervision of PhD students, contribute to our on-going projects, and also contribute to future project proposals to strengthen our research profile. Our group is member of multiple national and European research projects with strong links to industry. One example is the currently ongoing CRISALIS FP7 project (http://www.crisalisproject.eu/).
Successful candidates must hold a PhD degree in computer science or a closely related discipline and have demonstrated their excellence by top-class publications.
Please submit your application via the link provided below including:
The position will be closed as soon as a suitable candidate is found.