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On upper bounds for algebraic degrees of APN functions
Lilya Budaghyan, Claude Carlet, Tor Helleseth, Nian Li, Bo Sun
Foundations
We study the problem of existence of APN functions of algebraic degree $n$ over $\ftwon$. We characterize such functions by means of derivatives and power moments of the Walsh transform. We deduce some non-existence results which mean, in particular, that for most of the known APN functions $F$ over $\ftwon$ the function $x^{2^n-1}+F(x)$ is not APN, and changing a value of $F$ in a single point results in non-APN functions.
Cryptanalysis of a modern rotor machine in a multicast setting
Shane Kepley, David Russo, Rainer Steinwandt
Cryptographic protocols
At FSE '93, Anderson presented a modern byte-oriented ro-
tor machine that is suitable for fast software implementation. Building
on a combination of chosen ciphertexts and chosen plaintexts, we show
that in a setting with multiple recipients the recovery of an (equivalent) secret key can be feasible within minutes in a standard computer algebra system.
We study the problem of existence of APN functions of algebraic degree $n$ over $\ftwon$. We characterize such functions by means of derivatives and power moments of the Walsh transform. We deduce some non-existence results which mean, in particular, that for most of the known APN functions $F$ over $\ftwon$ the function $x^{2^n-1}+F(x)$ is not APN, and changing a value of $F$ in a single point results in non-APN functions.
At FSE '93, Anderson presented a modern byte-oriented ro- tor machine that is suitable for fast software implementation. Building on a combination of chosen ciphertexts and chosen plaintexts, we show that in a setting with multiple recipients the recovery of an (equivalent) secret key can be feasible within minutes in a standard computer algebra system.
