The 128-Bit Blockcipher CLEFIA
RFC 6114

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Independent Submission                                         M. Katagi
Request for Comments: 6114                                     S. Moriai
Category: Informational                                 Sony Corporation
ISSN: 2070-1721                                               March 2011

                     The 128-Bit Blockcipher CLEFIA

Abstract

   This document describes the specification of the blockcipher CLEFIA.
   CLEFIA is a 128-bit blockcipher, with key lengths of 128, 192, and
   256 bits, which is compatible with the interface of the Advanced
   Encryption Standard (AES).  The algorithm of CLEFIA was published in
   2007, and its security has been scrutinized in the public community.
   CLEFIA is one of the new-generation lightweight blockcipher
   algorithms designed after AES.  Among them, CLEFIA offers high
   performance in software and hardware as well as lightweight
   implementation in hardware.  CLEFIA will be of benefit to the
   Internet, which will be connected to more distributed and constrained
   devices.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This is a contribution to the RFC Series, independently of any other
   RFC stream.  The RFC Editor has chosen to publish this document at
   its discretion and makes no statement about its value for
   implementation or deployment.  Documents approved for publication by
   the RFC Editor are not a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6114.

Katagi & Moriai               Informational                     [Page 1]
RFC 6114             The 128-Bit Blockcipher CLEFIA           March 2011

Copyright Notice

   Copyright (c) 2011 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.

Table of Contents

   1. Introduction ....................................................3
   2. Notations .......................................................3
   3. CLEFIA Algorithm ................................................4
   4. CLEFIA Building Blocks ..........................................4
      4.1. GFN_{d,r} ..................................................4
      4.2. F-Functions ................................................6
      4.3. S-Boxes ....................................................7
      4.4. Diffusion Matrices .........................................9
   5. Data Processing Part ............................................9
      5.1. Encryption/Decryption ......................................9
      5.2. The Numbers of Rounds .....................................10
   6. Key Scheduling Part ............................................10
      6.1. DoubleSwap Function .......................................10
      6.2. Overall Structure .........................................11
      6.3. Key Scheduling for a 128-Bit Key ..........................11
      6.4. Key Scheduling for a 192-Bit Key ..........................11
      6.5. Key Scheduling for a 256-Bit Key ..........................12
      6.6. Constant Values ...........................................13
   7. Security Considerations ........................................18
   8. Informative References .........................................18
   Appendix A. Test Vectors ..........................................19
   Appendix B. Test Vectors (Intermediate Values) ....................19

Katagi & Moriai               Informational                     [Page 2]
RFC 6114             The 128-Bit Blockcipher CLEFIA           March 2011

1.  Introduction

   Due to the widespread use of the Internet, devices with limited
   capabilities, e.g., wireless sensors, are connected to the network.
   In order to realize enough security for the network, cryptographic
   technologies suitable for such constrained devices are very
   important.  This recent technology is called "lightweight
   cryptography", and the demand for lightweight cryptography is
   increasing.

   In order to satisfy these needs, a 128-bit blockcipher, CLEFIA, was
   designed based on state-of-the-art techniques [FSE07].  CLEFIA is a
   128-bit blockcipher, with key lengths of 128, 192, and 256 bits,
   which is compatible with the interface of AES [FIPS-197].  Since the
   cipher algorithm was published in 2007, its security has been
   scrutinized in the public community, but no security weaknesses have