Cryptology ePrint Archive: Report 2015/1148

An Inverse-free Single-Keyed Tweakable Enciphering Scheme

Ritam Bhaumik and Mridul Nandi

Abstract: In CRYPTO 2003, Halevi and Rogaway proposed CMC, a tweakable enciphering scheme (TES) based on a blockcipher. It requires two blockcipher keys and it is not inverse-free (i.e., the decryption algorithm uses the inverse (decryption) of the underlying blockcipher). We present here a new inverse-free, single-keyed TES. Our construction is a tweakable strong pseudorandom permutation (tsprp), i.e., it is secure against chosen-plaintext-ciphertext adversaries assuming that the underlying blockcipher is a pseudorandom permutation (prp), i.e., secure against chosen-plaintext adversaries. In comparison, sprp assumption of the blockcipher is required for the sprp security of CMC. Our scheme can be viewed as a mixture of type-1 and type-3 Feistel cipher and so we call it FMix or mixed-type Feistel cipher.

Category / Keywords: secret-key cryptography / (Tweakable Strong) pseudorandom permutation, Coefficient H Technique, Encipher, CMC, Feistel Cipher.

Original Publication (in the same form): IACR-ASIACRYPT-2015

Date: received 26 Nov 2015

Contact author: bhaumik ritam at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20151127:175736 (All versions of this report)

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