draft-ietf-openpgp-camellia-04.txt   rfc5581.txt 
Network Working Group D. Shaw Network Working Group D. Shaw
Updates: 4880 (if approved) Updates: 4880
Intended status: Standards Track Category: Informational
Expires: June 8, 2009
The Camellia Cipher in OpenPGP The Camellia Cipher in OpenPGP
draft-ietf-openpgp-camellia-04
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Abstract Abstract
This document presents the necessary information to use the Camellia This document presents the necessary information to use the Camellia
symmetric block cipher in the OpenPGP protocol. symmetric block cipher in the OpenPGP protocol.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements notation . . . . . . . . . . . . . . . . . . . . . 3 2. Requirements Notation . . . . . . . . . . . . . . . . . . . . . 2
3. Camellia . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Camellia . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
4. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 4. Security Considerations . . . . . . . . . . . . . . . . . . . . 2
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 3
6. Normative References . . . . . . . . . . . . . . . . . . . . . 4 6. Normative References . . . . . . . . . . . . . . . . . . . . . 3
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 4
Intellectual Property and Copyright Statements . . . . . . . . . . 5
1. Introduction 1. Introduction
The OpenPGP protocol [RFC4880] can support many different symmetric The OpenPGP protocol [RFC4880] can support many different symmetric
ciphers. This document presents the necessary information to use the ciphers. This document presents the necessary information to use the
Camellia [RFC3713] cipher in the OpenPGP protocol. Camellia [RFC3713] symmetric cipher in the OpenPGP protocol.
2. Requirements notation 2. Requirements Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Camellia 3. Camellia
Camellia is specified in [RFC3713]. It is a 128-bit block cipher (as Camellia is specified in [RFC3713]. It is a 128-bit symmetric block
are AES and Twofish in OpenPGP), that supports 128-bit, 192-bit, and cipher (as are AES and Twofish in OpenPGP) that supports 128-bit,
256-bit keys. This document defines the use of Camellia in OpenPGP. 192-bit, and 256-bit keys. This document defines the use of Camellia
in OpenPGP.
+---------------------+----------------------------------------+ +---------------------+----------------------------------------+
| Camellia Key Length | OpenPGP Symmetric-Key Algorithm Number | | Camellia Key Length | OpenPGP Symmetric-Key Algorithm Number |
+---------------------+----------------------------------------+ +---------------------+----------------------------------------+
| 128 | XXXX | | 128 | 11 |
| 192 | YYYY | | 192 | 12 |
| 256 | ZZZZ | | 256 | 13 |
+---------------------+----------------------------------------+ +---------------------+----------------------------------------+
[[To be allocated by IANA. Please fill this in: presumably XXXX ==
11, YYYY == 12, and ZZZZ == 13]]
OpenPGP applications MAY implement Camellia. If implemented, OpenPGP applications MAY implement Camellia. If implemented,
Camellia may be used in any place in OpenPGP where a symmetric cipher Camellia may be used in any place in OpenPGP where a symmetric cipher
is usable, and is subject to the same usage requirements (such as its is usable, and it is subject to the same usage requirements (such as
presence in the Preferred Symmetric Algorithms signature subpacket) its presence in the Preferred Symmetric Algorithms signature
as the other symmetric ciphers in OpenPGP. subpacket) as the other symmetric ciphers in OpenPGP.
While the OpenPGP algorithm preferences system prevents While the OpenPGP algorithm preferences system prevents
interoperability problems with public key encrypted messages, if interoperability problems with public key encrypted messages, if
Camellia (or any other optional cipher) is used for encrypting Camellia (or any other optional cipher) is used for encrypting
private keys, there could be interoperability problems when migrating private keys, there could be interoperability problems when migrating
a private key from one system to another. A similar issue can arise a private key from one system to another. A similar issue can arise
when using an optional cipher for symmetrically encrypted messages, when using an optional cipher for symmetrically encrypted messages,
as this OpenPGP message type does not perform cipher negotiation. as this OpenPGP message type does not use the algorithm preferences
Those using optional ciphers in this manner should take care they are system. Those using optional ciphers in this manner should take care
using a cipher that their intended recipient can decrypt. they are using a cipher that their intended recipient can decrypt.
4. Security Considerations 4. Security Considerations
At publication time, there are no known weak keys for Camellia, and At publication time, there are no known weak keys for Camellia, and
the Camellia algorithm is believed to be strong. However, as with the Camellia algorithm is believed to be strong. However, as with
any technology involving cryptography, implementers should check the any technology involving cryptography, implementers should check the
current literature, as well as the Camellia home page at current literature, as well as the Camellia home page at
<http://info.isl.ntt.co.jp/camellia/>, to determine if Camellia has http://info.isl.ntt.co.jp/camellia/ to determine if Camellia has been
been found to be vulnerable to attack. found to be vulnerable to attack.
5. IANA Considerations 5. IANA Considerations
This document requires IANA to assign three algorithm numbers from IANA assigned three algorithm numbers from the registry of OpenPGP
the registry of OpenPGP Symmetric-Key Algorithms that was created by Symmetric-Key Algorithms that was created by [RFC4880].
[RFC4880].
6. Normative References 6. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3713] Matsui, M., Nakajima, J., and S. Moriai, "A Description of [RFC3713] Matsui, M., Nakajima, J., and S. Moriai, "A Description of
the Camellia Encryption Algorithm", RFC 3713, April 2004. the Camellia Encryption Algorithm", RFC 3713, April 2004.
[RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R. [RFC4880] Callas, J., Donnerhacke, L., Finney, H., Shaw, D., and R.
Thayer, "OpenPGP Message Format", RFC 4880, November 2007. Thayer, "OpenPGP Message Format", RFC 4880, November 2007.
Author's Address Author's Address
David Shaw David Shaw
Email: dshaw@jabberwocky.com EMail: dshaw@jabberwocky.com
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