Cryptology ePrint Archive: Report 2001/046
The simple ideal cipher system
Abstract: We address the problem of how to construct ideal cipher systems when the
of a key is much less than the length of an encrypted message. We suggest a
secret key cipher system in which firstly the message is transformed into two
parts in such a
the biggest part consists of independent and equiprobable letters.
Secondly the relatively small second part is enciphered wholly by the Vernam
whereas only few bits from the biggest part are enciphered.
This transformation is based on the fast version of the Elias
construction of an unbiased random sequence.
time required for encoding and decoding and the memory size of the encoder and
decoder are presented as functions
of the ratio of the key length and the message length.
The suggested scheme can be applied to sources with unknown statistics.
Category / Keywords: secret-key cryptography / ideal cipher system,fast algorithms,Shannon entropy
Date: received 4 Jun 2001
Contact author: ryabko at neic nsk su
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Version: 20010607:112333 (All versions of this report)
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