A Description of KCipher-2 Encryption Algorithm
draft-kiyomoto-kcipher2-08

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Internet Draft                                              S. Kiyomoto
Intended status: Informational                                  W. Shin
Expires: June 2013                          KDDI R&D Laboratories, Inc.
                                                      December 16, 2012

              A Description of KCipher-2 Encryption Algorithm
                      draft-kiyomoto-kcipher2-08.txt

Abstract

   This document describes the KCipher-2 encryption algorithm. KCipher-2
   is a stream cipher with a 128-bit key and a 128-bit initialization
   vector. Since the algorithm for KCipher-2 was published in 2007,
   security and efficiency have been rigorously evaluated through
   academic and industrial studies. No security vulnerability has been
   found as of the time this document was written. KCipher-2 offers fast
   encryption and decryption by means of simple operations that enable
   efficient implementation. KCipher-2 has been used for industrial
   applications, especially for mobile health monitoring and diagnostic
   services in Japan.

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79. This document may not be modified,
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   This Internet-Draft will expire on June 16, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors. All rights reserved.

Kiyomoto & Shin       Expires June 16, 2013                    [Page 1]
Internet-Draft         KCipher-2 Stream Cipher            December 2012

   This document is subject to BCP 78 and the IETF Trust's Legal
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   (http://trustee.ietf.org/license-info) in effect on the date of
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   described in the Simplified BSD License.

Table of Contents

   1. Introduction...................................................3
   2. Algorithm Description..........................................4
      2.1. Notations.................................................4
      2.2. Internal State............................................4
         2.2.1. Feedback Shift Registers.............................5
         2.2.2. Internal registers...................................5
      2.3. Operations................................................5
         2.3.1. next()...............................................5
         2.3.2. init()...............................................7
         2.3.3. stream().............................................8
      2.4. Subroutines...............................................9
         2.4.1. NLF()................................................9
         2.4.2. sub_K2().............................................9
         2.4.3. S_box().............................................10
         2.4.4. Multiplications in GF(2#32).........................11
      2.5. Encryption/Decryption scheme.............................13
         2.5.1. Key stream generation...............................13
         2.5.2. Encryption/Decryption of a message..................14
   3. Security Considerations.......................................14
   4. References....................................................14
      4.1. Normative References.....................................14
      4.2. Informative References...................................15
   Appendix A. Tables for multiplication in GF(2#32)................16
      A.1. The table amul0..........................................16
      A.2. The table amul1..........................................17
      A.3. The table amul2..........................................19
      A.4. The table amul3..........................................20
   Appendix B. A simple implementation example of KCipher-2.........22
      B.1. Code components I - Definitions and declarations.........22
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