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This paper discusses a known-plaintext attack on a redundancy reducing cipher method which is proposed by Wayner. We also propose an extension of Wayner’s redundancy reducing cipher scheme so that the security will be improved greatly.

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We prove that the set of DES permutations (encryption and decryption for each DES key) is not closed under functional composition. This implies that, in general, multiple DES-encryption is not equivalent to single DES-encryption, and that DES is not susceptible to a particular known-plaintext attack which requires, on average, 228 steps. We also show that the size of the subgroup generated by t...

As noted below, most researchers agree that young babies should sleep in the same room where their parents sleep. The point of disagreement is whether parents should be advised against sharing their beds. Some researchers think that the safest arrangement involves cosleeping without sharing the same bed—-i.e., placing a young infant in a crib or “side car” that is within arm’s reach of his parent.

Cribbage is (normally) a two-player card game where the aim is to score 121 points before your opponent. The game has four stages, one of which involves discarding two cards from the six cards you are dealt. A later stage scores the four cards in your hand together with a card cut randomly from the deck after the discards have been made. The two cards that were discarded are used to form anothe...

The most recent results and some of the open key questions on the evolution of early-type galaxies are reviewed in the general cosmological context of massive galaxy formation.