A Description of the KCipher-2 Encryption Algorithm
RFC 7008
| Document | Type |
RFC - Informational
(August 2013; No errata)
Was draft-kiyomoto-kcipher2 (individual)
|
|
|---|---|---|---|
| Last updated | 2013-08-28 | ||
| Stream | ISE | ||
| Formats | plain text pdf html bibtex | ||
| IETF conflict review | conflict-review-kiyomoto-kcipher2 | ||
| Stream | ISE state | Published RFC | |
| Consensus Boilerplate | Unknown | ||
| Document shepherd | No shepherd assigned | ||
| IESG | IESG state | RFC 7008 (Informational) | |
| Telechat date | |||
| Responsible AD | (None) | ||
| Send notices to | (None) | ||
Independent Submission S. Kiyomoto
Request for Comments: 7008 W. Shin
Category: Informational KDDI R&D Laboratories, Inc.
ISSN: 2070-1721 August 2013
A Description of the KCipher-2 Encryption Algorithm
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. As of the
publication of this document, no security vulnerabilities have been
found. 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 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/rfc7008.
Copyright Notice
Copyright (c) 2013 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.
Kiyomoto & Shin Informational [Page 1]
RFC 7008 A Description of KCipher-2 August 2013
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Algorithm Description . . . . . . . . . . . . . . . . . . . . 3
2.1. Notations . . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Internal State . . . . . . . . . . . . . . . . . . . . . . 4
2.2.1. Feedback Shift Registers . . . . . . . . . . . . . . . 4
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 and Decryption Scheme . . . . . . . . . . . . . 13
2.5.1. Key Stream Generation . . . . . . . . . . . . . . . . 13
2.5.2. Encryption and Decryption of a Message . . . . . . . . 14
3. Security Considerations . . . . . . . . . . . . . . . . . . . 14
4. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
4.1. Normative References . . . . . . . . . . . . . . . . . . . 14
4.2. Informative References . . . . . . . . . . . . . . . . . . 14
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
B.2. Code Components II - Functions . . . . . . . . . . . . . . 23
B.3. Use Case . . . . . . . . . . . . . . . . . . . . . . . . . 28
Appendix C. Test Vectors . . . . . . . . . . . . . . . . . . . . 28
C.1. Key Stream Generation Examples . . . . . . . . . . . . . . 28
C.2. Another Key Stream Generation with the State Values . . . 29
C.2.1. S after init(1) . . . . . . . . . . . . . . . . . . . 30
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