Identity and particularly access control present various challenges, particularly for larger organisations. The combined complexity of users from various communities, accessing multiple systems and applications in the context of business processes can be significant. The US MIST proposed the Role- Based Access Control model in order to effectively and efficiently manage authorisations. While this model certainly also has its drawbacks, it gave rise to various interesting software solutions. One particularly relevant one is the Sage tool. This tool builds a model of the actual authorisations across platforms by consolidating and enriching them in its own database. Subsequently, the built-in pattern- matching engine can identify a number of less desirable patterns in the data and can recommend solutions, e.g., for role structuring (role-mining). Furthermore, business constraints can be expressed in so-called business process rules, which can, e.g., reflect segregation of duty requirements.

HAVAL is a cryptographic hash function proposed in 1992 by Zheng, Pieprzyk and Seberry. Its has a structure that is quite similar to other well-known hash functions such as MD4 And MD5. The specification of HAVAL includes a security parameter, the number of passes (that is, the number of times that a particular word of the message is used in the computation) can be chosen equal to 3, 4 or 5. In this paper we describe a practical attack that finds collisions for the 3-pass version of HAVAL. This means that it is possible to generate pairs of messages hashing to the same value. The computational complexity of the attack corresponds to about 2(29) computations of the compression function of 3-pass HAVAL; the required amount of memory is negligible.

IST-2000-12324 Project Title NESSIE Deliverable Type Report Security Class Public Deliverable Number D21 Title of Deliverable Performance of Optimized Implementations of the NESSIE Primitives Document Reference NES/DOC/TEC/WP6/D21/1 Contractual Date of Delivery Y3 M11 Actual Date of Delivery Y3 M11 Editors Technion Abstract Performance of Optimized Implementations of the NESSIE Primitives

Performance of Optimized Implementationsof the NESSIE PrimitivesKeywords NESSIE, Performance Evaluation.Version 2.0Performance of Optimized Implementations of theNESSIE Primitives +B. Preneel, B. Van Rompay, S. B.

PANAMA is a cryptographic module that was presented at the FSE Workshop in '98 by Joan Daemen and Craig Clapp. It can serve both as a stream cipher and as a cryptographic hash function, with a hash result of 256 bits. PANAMA achieves high performance (for large amounts of data) because of its inherent parallelism. We will analyse the security of PANAMA when used as a hash function, and demonstrate an attack able to find collisions much faster than by birthday attack. The computational complexity of our current attack is 2 82; the required amount of memory is negligible.

We present a new message authentication code. It is based on a two trail construction, which underlies the unkeyed hash function RIPEMD-160. It is in comparison with the MDx-MAC based on RIPEMD-160, much more efficient on short messages (that is on messages of 512 or 1024 bits) and percentage-wise a little bit more efficient on long messages. Moreover, it handles key-changes very efficiently. This positive fact remains if we compare our Two-Track-MAC with HMAC based on RIPEMD-160.

this report has been supported by the Commission of the European Communitiesthrough the IST program under contract IST-1999-12324. The information in this document is providedas is, and no warranty is given or implied that the information is fit for any particular purpose. The userthereof uses the information at its sole risk and liability

We present a new message authentication code. It is based on a two trail construction, which underlies the unkeyed hash func- tion RIPEMD-160. It is in comparison with the MDx-MAC based on RIPEMD-160, much more efficient on short messages (that is on mes- sages of 512 or 1024 bits) and percentage-wise a little bit more efficient on long messages. Moreover, it handles key-changes very efficiently. This positive fact remains if we compare our Two-Track-MAC with HMAC based on RIPEMD-160.

† The work described in this report has been supported by the Commission of the European Communities through the IST program under contract IST-1999-12324. The information in this document is provided as is, and no warranty is given or implied that the information is fit for any particular purpose. The user thereof uses the information at its sole risk and liability.

ICE is a 64-bit block cipher presented at the Fast Software Encryption Workshop in January 1997. It introduced the concept of a keyed permutation to improve the resistance against differential and linear cryptanalysis. In this paper we will show however that we can use low Hamming weighted differences to perform a practical, key dependent, differential attack on ICE. The main conclusion is that the keyed permutation is not as effective as it was conjectured to be.

Cryptographic hash functions are an important building block for a wide range of applications such as the authentication of information, digital signatures and the protection of pass-phrases. The most popular hash functions are the custom designed iterative hash functions from the MD4 family. Over the years various results on the cryptanalysis of these functions have become available and this paper intends to summarize these results and their impact. We will describe attacks on MD4, MD5 and RIPEMD, and discuss the design and security of the hash functions SHA-1 and RIPEMD-160 which are included in the new standard ISO/IEC 10118-3.

In this paper we examine the relation between time and cryptography. Timestamping systems provide temporal authentication of electronic documents, they certify the date a document was created or last modifled. Important applications are found in legal situations, electronic contracts, the protection of Intellectual Property Rights, and Internet security in general. We give an overview of the problem and discuss several state-of-the-art techniques.