Rodolphe Lampe

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We analyze the security of the iterated Even-Mansour cipher (a.k.a. key-alternating cipher), a very simple and natural construction of a blockcipher in the random permutation model. This construction, first considered by Even and Mansour (J. Cryptology, 1997) with a single permutation, was recently generalized to use t permutations in the work of Bogdanov(More)
We consider tweakable blockciphers with beyond the birthday bound security. Landecker, Shrimpton, and Terashima (CRYPTO 2012) gave the first construction with security up to O(22n/3) adversarial queries (n denotes the block size in bits of the underlying blockcipher), and for which changing the tweak does not require changing the keys for blockcipher calls.(More)
We studied the mechanism by which the peptide omega-grammotoxin-SIA inhibits voltage-dependent calcium channels. Grammotoxin at concentrations of > 50 nM completely inhibited inward current carried by 2 mM barium through P-type channels in rat cerebellar Purkinje neurons when current was elicited by depolarizations up to +40 mV. However, outward current(More)
omega-Grammotoxin SIA, a peptidergic blocker of voltage-sensitive calcium channel (VSCC) responses, was purified from Grammostola spatulata (tarantula spider) venom by reverse phase high performance liquid chromatography. Protease-sensitive biological activity was monitored by determining the inhibition of K(+)-stimulated influx of 45Ca2+ into rat brain(More)
We show how to construct an ideal cipher with n-bit blocks and n-bit keys (i.e. a set of 2 public n-bit permutations) from a small constant number of n-bit random public permutations. The construction that we consider is the single-key iterated Even-Mansour cipher, which encrypts a plaintext x ∈ {0, 1} under a key k ∈ {0, 1} by alternatively xoring the key(More)
The r-round (iterated) Even-Mansour cipher (also known as key-alternating cipher) defines a block cipher from r fixed public n-bit permutations P1, . . . , Pr as follows: given a sequence of n-bit round keys k0, . . . , kr, an n-bit plaintext x is encrypted by xoring round key k0, applying permutation P1, xoring round key k1, etc. The (strong)(More)
We study the security of key-alternating Feistel ciphers, a class of key-alternating ciphers with a Feistel structure. Alternatively, this may be viewed as the study of Feistel ciphers where the pseudorandom round functions are of the form Fi(x⊕ ki), where ki is the (secret) round key and Fi is a public random function that the adversary is allowed to query(More)
The peptide Ca2+ channel antagonists omega-conotoxin (omega-CTX) MVIIC and omega-grammotoxin (omega-GTX) SIA were studied by measuring their effects on the release of [3H]glutamate from rat brain synaptosomes. The pseudo-first-order association constant for omega-CTX MVIIC (1.1 x 10(4) M-1 sec-1) was small, relative to that for omega-GTX SIA (3.6 x 10(5)(More)
The effects of synthetic omega-grammotoxin SIA (omega-GsTxSIA) and synthetic omega-Aga-IVA were tested in in vitro and in vivo neurochemical assays that are reflective of voltage-sensitive calcium channel function. Synthetic omega-GsTx SIA inhibited K(+)-evoked rat and chick synaptosomal 45Ca2+ flux, K(+)-evoked release of [3H]D-aspartate and(More)
We study how to construct efficient tweakable block ciphers in the Random Permutation model, where all parties have access to public random permutation oracles. We propose a construction that combines, more efficiently than by mere black-box composition, the CLRW construction (which turns a traditional block cipher into a tweakable block cipher) of(More)