International Association for Cryptologic Research

International Association
for Cryptologic Research

CryptoDB

Joos Vandewalle

Publications

Year
Venue
Title
2003
ASIACRYPT
2003
FSE
2002
PKC
2002
EPRINT
Square Attacks on Reduced-Round Variants of the Skipjack Block Cipher
This report surveys on a series of Square attacks on reduced-round versions of the Skipjack block cipher. {\bf Skipjack} is an iterated block cipher encrypting 64-bit plaintext blocks into 64-bit ciphertext blocks, using an 80-bit key. Its design is based on a generalized Feistel Network making up 32 rounds of two different types. This cipher was developed by the National Security Agency for the Clipper chip and Fortezza PC card.
2002
EPRINT
Applying General Access Structure to Metering Schemes
In order to decide on advertisement fees for web servers, Naor and Pinkas introduced metering schemes secure against coalition of corrupt servers and clients. In their schemes any server is able to construct a proof to be sent to an audit agency if and only if it has been visited by at least a certain number of clients. Several researchers have generalized the idea of Naor and Pinkas: first metering scheme with pricing and dynamic multi-threshold metering schemes have been proposed; later the solution has been extended to allow for general access structures and an approach on linear algebra has been introduced. In this paper we are interested in the efficiency of applying general access structures and linear algebra techniques to metering schemes. We propose a new model considering general access structures for clients, corrupted clients and servers. Then we bind the access structures for clients and corrupted clients into one. We propose a new metering scheme, which is more efficient w.r.t.\ communication complexity and memory requirements than the scheme of Blundo \textit{et al.}
2002
EPRINT
A note on Weak Keys of PES, IDEA and some Extended Variants
This paper presents an analysis of the PES cipher in a similar setting as done by Daemen et al. at Crypto'93 for IDEA. The following results were obtained for 8.5 round PES: a linear weak-key class of size $2^{48}$; two distinct differential weak-key classes of size $2^{41}$; two differential-linear weak-key classes of size $2^{62}$. For 17-round PES (double-PES): a linear weak-key class of size $2^7$, and a differential weak-key class of size $2^7$ were found. Daemen suggested a modified key schedule for IDEA in order to avoid weak keys. We found a differential weak-key class of size $2^{83}$ for 2.5-round IDEA under his redesigned key schedule, and differential-linear relations for 3.5-round IDEA.
2002
EPRINT
Applying General Access Structure to Proactive Secret Sharing Schemes
Verifiable secret sharing schemes (VSS) are secret sharing schemes (SSS) dealing with possible cheating by participants. In this paper we use the VSS proposed by Cramer, Damgard and Maurer \cite{CDM99,CDM00,Cra00}. They introduced a purely linear algebraic method to transform monotone span program (MSP) based secret sharing schemes into VSS. In fact, the monotone span program model of Karchmer and Wigderson \cite{KW93} deals with arbitrary monotone access structures and not just threshold ones. Stinson and Wei \cite{SW99} proposed a proactive SSS based on threshold (polynomial) VSS. The purpose of this paper is to build unconditionally secure proactive SSS over any access structure, as long as it admits a linear secret sharing scheme (LSSS).
2001
EUROCRYPT
2001
FSE
2001
FSE
2001
EPRINT
SQUARE Attacks on Reduced-Round PES and IDEA Block Ciphers
This paper reports on variants of the Square attack applied to reduced-round versions of the PES and IDEA block ciphers. Attacks on 2.5 rounds of IDEA require $3\cdot 2^{16}$ chosen-plaintexts and recover 78 key bits. A new kind of attack, the Square related-key attack, is applied on 2.5 rounds of IDEA and recovers 32 key bits, with 2 chosen-plaintexts and $2^{17}$ related keys. Similar results hold for 2.5 rounds of PES. Implementations of the attacks on 32-bit block mini-versions of both ciphers confirmed the expected computational complexity. Although our attacks do not improve on previous approaches, this report shows new variants of the Square attack on word-oriented block ciphers like IDEA and PES.
2000
FSE
1999
FSE
1997
EUROCRYPT
1996
ASIACRYPT
1996
CRYPTO
1994
FSE
1993
CRYPTO
1993
CRYPTO
1993
CRYPTO
1993
EUROCRYPT
1993
FSE
1992
AUSCRYPT
1992
AUSCRYPT
1991
ASIACRYPT
1991
ASIACRYPT
1991
EUROCRYPT
1990
EUROCRYPT
1989
CRYPTO
1989
EUROCRYPT
1988
EUROCRYPT
1987
EUROCRYPT
1987
EUROCRYPT
1986
EUROCRYPT
1985
EUROCRYPT
1983
CRYPTO

Program Committees