draft-ietf-smime-idea-02.txt   draft-ietf-smime-idea-03.txt 
Internet Draft S. Teiwes, Internet Draft S. Teiwes,
draft-ietf-smime-idea-02.txt P. Hartmann, draft-ietf-smime-idea-03.txt P. Hartmann,
February 22, 1999 D. Kuenzi, April 10, 2000 D. Kuenzi,
Expires in six months iT_Security Ltd. Expires in six months iT_Security Ltd.
Incorporation of the IDEA Encryption Algorithm in S/MIME Incorporation of IDEA Encryption Algorithm in S/MIME
Status of this Memo Status of this Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with
all provisions of section 10 of RFC2026. Internet-Drafts are all provisions of section 10 of RFC2026. Internet-Drafts are
working documents of the Internet Engineering Task Force (IETF), working documents of the Internet Engineering Task Force (IETF),
its areas, and its working groups. Note that other groups may also its areas, and its working groups. Note that other groups may also
distribute working documents as Internet-Drafts. distribute working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
skipping to change at line 36 skipping to change at line 36
To view the entire list of current Internet-Drafts, please check the To view the entire list of current Internet-Drafts, please check the
"1id-abstracts.txt" listing contained in the Internet-Drafts Shadow "1id-abstracts.txt" listing contained in the Internet-Drafts Shadow
Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern Directories on ftp.is.co.za (Africa), ftp.nordu.net (Northern
Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific Europe), ftp.nis.garr.it (Southern Europe), munnari.oz.au (Pacific
Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast). Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast).
1. Introduction 1. Introduction
This memo specifies how to incorporate IDEA (International Data This memo specifies how to incorporate IDEA (International Data
Encryption Algorithm) [IDEA] into S/MIME [SMIME2, SMIME3] as an Encryption Algorithm) [IDEA] into S/MIME [SMIME2, SMIME3] as
additional algorithm for symmetric encryption. Today, IDEA is widely an additional strong algorithm for symmetric encryption. For
applied in electronic business applications. But it is not organizations who make use of IDEA for data security purposes
considered in the specification [SMIME3]. Encryption algorithms are it is of high interest that IDEA is also available in S/MIME.
part of an organizations' security policy. Typically, organizations The intention of this memo is to provide the OIDs and algorithms
like to have their own preferences in this respect. Therefore, it is required that IDEA can be included in S/MIME for symmetric content
beneficial to have the choice between different well-known encryption and key encryption.
algorithms. Especially for those organization who make already use
of IDEA on a wide scale it is of high interest that IDEA is also
available in S/MIME. It is the intention of this memo to provide the
OIDs and algorithms required to include IDEA in S/MIME for symmetric
content and key encryption.
The general functional capabilities and preferences of S/MIME are The general functional capabilities and preferences of S/MIME are
specified by the registered list of S/MIME object identifiers (OIDs). specified by the registered list of S/MIME object identifiers (OIDs).
This list of OIDs is maintained by the Internet Mail Consortium at This list of OIDs is maintained by the Internet Mail Consortium at
<http://www.imc.org/ietf-smime/oids.html>. <http://www.imc.org/ietf-smime/oids.html>.
The set of S/MIME functions provided by a client is expressed by the The set of S/MIME functions provided by a client is expressed by the
S/MIME capabilities attribute. This attribute contains a list of OIDs S/MIME capabilities attribute. This attribute contains a list of OIDs
of supported cryptographic functions. of supported cryptographic functions.
This draft is being discussed on the "ietf-smime" mailing list. To This draft is being discussed on the "ietf-smime" mailing list. To
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cryptographic functions and must be signed by the client. These OIDs cryptographic functions and must be signed by the client. These OIDs
should be logically separated in functional categories and MUST be should be logically separated in functional categories and MUST be
ordered with respect to their preference. If an S/MIME client is ordered with respect to their preference. If an S/MIME client is
required to support symmetric encryption and key wrapping based on required to support symmetric encryption and key wrapping based on
IDEA, the capabilities attribute MUST contain the above specified IDEA, the capabilities attribute MUST contain the above specified
OIDs in the category of symmetric algorithms and key encipherment OIDs in the category of symmetric algorithms and key encipherment
algorithms. IDEA does not require additional OID parameters since algorithms. IDEA does not require additional OID parameters since
it has a fixed key length of 128 bits. it has a fixed key length of 128 bits.
The SMIMECapability SEQUENCE representing the IDEA symmetric The SMIMECapability SEQUENCE representing the IDEA symmetric
encrytion algorithm MUST include the IDEA-CBC OID in the capabilityID encryption algorithm MUST include the IDEA-CBC OID in the capabilityID
field and the parameters field MUST be absent. The SMIMECapability field and the parameters field MUST be absent. The SMIMECapability
SEQUENCE for IDEA encryption SHOULD be included in the symmetric SEQUENCE for IDEA encryption SHOULD be included in the symmetric
encryption algorithms portion of the SMIMECapabilities list. The encryption algorithms portion of the SMIMECapabilities list. The
SMIMECapability SEQUENCE representing IDEA MUST be DER-encoded as SMIMECapability SEQUENCE representing IDEA MUST be DER-encoded as
follows: 300F 060B 2B06 0104 0181 3C07 0101 0205 00. follows: 300F 060B 2B06 0104 0181 3C07 0101 0205 00.
The SMIMECapability SEQUENCE representing the IDEA key wrapping The SMIMECapability SEQUENCE representing the IDEA key wrapping
algorithm MUST include the id-alg-CMSIDEAwrap OID in the capabilityID algorithm MUST include the id-alg-CMSIDEAwrap OID in the capabilityID
field and the parameters field of KeyWrapAlgorithm MUST be absent. field and the parameters field of KeyWrapAlgorithm MUST be absent.
The SMIMECapability SEQUENCE for IDEA key wrapping SHOULD be included The SMIMECapability SEQUENCE for IDEA key wrapping SHOULD be included
in the key encipherment algorithms portion of the SMIMECapabilities in the key encipherment algorithms portion of the SMIMECapabilities
list. The SMIMECapability SEQUENCE representing IDEA key wrapping list. The SMIMECapability SEQUENCE representing IDEA key wrapping
MUST be DER-encoded as follows: 300F 060B 2B06 0104 0181 3C07 0101 MUST be DER-encoded as follows: 300F 060B 2B06 0104 0181 3C07 0101
0605 00. 0605 00.
5. Activation of IDEA in S/MIME 5. Activation of IDEA in S/MIME Clients
When a sending agent creates an encrypted message, it has to decide When a sending agent creates an encrypted message, it has to decide
which type of encryption algorithm to use. In general the decision which type of encryption algorithm to use. In general the decision
process involves information obtained from the capabilities lists process involves information obtained from the capabilities lists
included in messages received from the recipient, as well as other included in messages received from the recipient, as well as other
information such as private agreements, user preferences, legal information such as private agreements, user preferences, legal
restrictions, etc. If users require IDEA for symmetric encryption, restrictions, etc. If users require IDEA for symmetric encryption,
it must be supported by the S/MIME clients on both the sending and it must be supported by the S/MIME clients on both the sending and
receiving side, and it must be set in the user preferences. receiving side, and it must be set in the user preferences.
A. References A. References
[IDEA] X. Lai, "On the design and security of block ciphers", ETH [IDEA] X. Lai, "On the design and security of block ciphers", ETH
Series in Information Processing, J.L. Massey (editor), vol. 1, Series in Information Processing, J.L. Massey (editor), vol. 1,
Hartung-Gorre Verlag Konstanz, Technische Hochschule (Zurich), 1992. Hartung-Gorre Verlag Konstanz, Technische Hochschule (Zurich), 1992.
A. J. Menezes, P.C. v. Oorschot, S.A. Vanstone, "Handbook of Applied A. J. Menezes, P.C. v. Oorschot, S.A. Vanstone, "Handbook of Applied
Cryptography," CRC Press New York, 1997, p. 265. Cryptography," CRC Press New York, 1997, p. 265.
B. Schneier, "Applied Cryptography," 2nd ed., John Wiley & Sons Inc. B. Schneier, "Applied Cryptography," 2nd ed., John Wiley & Sons Inc.
New York, 1996, pp. 319-325. New York, 1996, pp. 319-325.
IPR: see the "IETF Page of Intellectual Property Rights Notices",
http://www.ietf.org/ipr.html
[SMIME2] "S/MIME Version 2 Message Specification", RFC 2311, and [SMIME2] "S/MIME Version 2 Message Specification", RFC 2311, and
"S/MIME Version 2 Certificate Handling", RFC 2312. "S/MIME Version 2 Certificate Handling", RFC 2312.
[SMIME3] "S/MIME Version 3 Certificate Handling", RFC 2632, and [SMIME3] "S/MIME Version 3 Certificate Handling", RFC 2632, and
"S/MIME Version 3 Message Specification", RFC 2633. "S/MIME Version 3 Message Specification", RFC 2633.
[MUSTSHOULD] "Key words for use in RFCs to Indicate Requirement [MUSTSHOULD] "Key words for use in RFCs to Indicate Requirement
Levels", RFC 2119. Levels", RFC 2119.
[CMS] "Cryptographic Message Syntax", RFC 2630. [CMS] "Cryptographic Message Syntax", RFC 2630.
[PKCS7] "PKCS #7: Cryptographic Message Syntax Version 1.5", [PKCS7] "PKCS #7: Cryptographic Message Syntax Version 1.5",
RFC 2315. RFC 2315.
B. Comments on IDEA Security and Standards B. Comments on IDEA Security and Standards
The IDEA algorithm was developed in a joint project involving the The IDEA algorithm was developed in a joint project involving the
Swiss Federal Institute of Technology in Zurich (Dr. X. Lai and Swiss Federal Institute of Technology in Zurich (Dr. X. Lai and
Prof. J.L. Massey) and Ascom Ltd. The aim of the project was to Prof. J.L. Massey) and Ascom Ltd. The aim of the project was to
develop an encryption algorithm which would replace the DES develop a strong encryption algorithm that could replace the DES
algorithm. algorithm.
IDEA uses 128-bit secret keys and encrypts one 64-bit block at a IDEA uses 128-bit secret keys and encrypts one 64-bit block at a
time. Experts in cryptography consider IDEA to be a highly secure time [IDEA]. It was particularly strengthened to protect against
symmetric cipher [IDEA]. It was particularly strengthened to protect differential cryptoanalysis attacks. For the full 8-round IDEA
against differential cryptoanalysis attacks. For the full 8-round there is no attack known which is better than exhaustive search
IDEA there is no attack known which is better than exhaustive search
on the total 128-bit key space. on the total 128-bit key space.
IDEA permits the implementation of standard Electronic Data IDEA permits the implementation of standard Electronic Data
Interchange applications. It has been entered in the ISO/IEC register Interchange applications. It has been entered in the ISO/IEC register
for encryption algorithms and incorporated in the "SECURITY GUIDE for encryption algorithms and incorporated in the "SECURITY GUIDE
LINES" code list by the UNI/EDIFACT "SECURITY JOINT WORKING GROUP". LINES" code list by the UNI/EDIFACT "SECURITY JOINT WORKING GROUP".
More information on IDEA can be found at More information on IDEA and an implementation in C code can be found
<http://www.it-sec.com/idea_alg.html>. at <http://www.it-sec.com/idea_alg.html>.
C. Intellectual Property Notice C. Intellectual Property Rights Notice
Ascom Ltd. holds the patent to IDEA. In accordance with the
intellectual property rights procedures of the IETF standards
process, Ascom offers a non-exclusive license under reasonable and
non-discriminatory terms and conditions.
IDEA (TM) is protected by international copyright law and in addition IDEA (TM) is protected by international copyright law and in addition
it has been patented in the United States, Japan, and in most of the has been patented in several countries. Because Ascom wants to make
European countries. The patent is held by Ascom Ltd. this highly secure algorithm widely available, the non-commercial use
of this algorithm is free.
Non-commercial use of IDEA is free. Any party wishing to request a license should visit the web site
Commercial licenses can be easily obtained via online order or by <http://www.it-sec.com/> or send an e-mail to Idea@it-sec.com.
contacting idea@it-sec.com. Detailed licensing information can be found
at <http://www.it-sec.com/idea_lic.html>. Detailed licensing information can be found at
<http://www.it-sec.com/idea_lic.html>.
D. Acknowledgements D. Acknowledgements
We would like to thank Jim Schaad and Francois Zeller for their We would like to thank Jim Schaad and Francois Zeller for their
contributions to this document. contributions to this document.
E. Authors' Address E. Authors' Address
iT_Security Ltd. iT_Security Ltd.
Badenerstrasse 530 Badenerstrasse 530
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