Elastic Block Ciphers in Practice: Constructions and Modes of Encryption

  • Debra L. Cook*
  • Moti Yung
  • Angelos D. Keromytis
Part of the Lecture Notes in Electrical Engineering book series (LNEE, volume 30)


We demonstrate the general applicability of the elastic block cipher method by constructing examples from existing block ciphers: AES, Camellia, MISTY1 and RC6. An elastic block cipher is a variable-length block cipher created from an existing fixed-length block cipher. The elastic version supports any block size between one and two times that of the original block size. We compare the performance of the elastic versions to that of the original versions and evaluate the elastic versions using statistical tests measuring the randomness of the ciphertext. The benefit, in terms of an increased rate of encryption, of using an elastic block cipher varies based on the specific block cipher and implementation. In most cases, there is an advantage to using an elastic block cipher to encrypt blocks that are a few bytes longer than the original block length. The statistical test results indicate no obvious flaws in the method for constructing elastic block ciphers. We also use our examples to demonstrate the concept of a generic key schedule for block ciphers. In addition, we present ideas for new modes of encryption using the elastic block cipher construction.


Block Size Block Cipher Advance Encryption Standard Performance Benefit Round Function 


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Copyright information

© Springer Science+Business Media, LLC 2009

Authors and Affiliations

  • Debra L. Cook*
    • 1
  • Moti Yung
    • 2
  • Angelos D. Keromytis
    • 2
  1. 1.Columbia UniversityNew YorkUSA
  2. 2.Department of Computer ScienceColumbia UniversityNew YorkUSA

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