Network Working Group P. Hoffman
Request for Comments: 4308 VPN Consortium
Category: Standards Track December 2005
Cryptographic Suites for IPsec
Status of This Memo
This document specifies an Internet standards track protocol for the
Internet community, and requests discussion and suggestions for
improvements. Please refer to the current edition of the "Internet
Official Protocol Standards" (STD 1) for the standardization state
and status of this protocol. Distribution of this memo is unlimited.
Copyright (C) The Internet Society (2005).
The IPsec, Internet Key Exchange (IKE), and IKEv2 protocols rely on
security algorithms to provide privacy and authentication between the
initiator and responder. There are many such algorithms available,
and two IPsec systems cannot interoperate unless they are using the
same algorithms. This document specifies optional suites of
algorithms and attributes that can be used to simplify the
administration of IPsec when used in manual keying mode, with IKEv1
or with IKEv2.
This document is a companion to IPsec [RFC2401] and its two key
exchange protocols, IKE [RFC2409] and IKEv2 [IKEv2]. Like most
security protocols, IPsec, IKE, and IKEv2 allow users to chose which
cryptographic algorithms they want to use to meet their security
Implementation experience with IPsec in manual key mode and with IKE
has shown that there are so many choices for typical system
administrators to make that it is difficult to achieve
interoperability without careful pre-agreement. Because of this, the
IPsec Working Group agreed that there should be a small number of
named suites that cover typical security policies. These suites may
be presented in the administrative interface of the IPsec system.
These suites, often called "UI suites" ("user interface suites"), are
optional and do not prevent implementers from allowing individual
selection of the security algorithms.
Hoffman Standards Track [Page 1]RFC 4308 Cryptographic Suites for IPsec December 2005
Although the UI suites listed here are optional to implement, this
document is on the standards track because implementers who call
particular suites by the names used here have to conform to the
suites listed in this document. These suites should not be
considered extensions to IPsec, IKE, and IKEv2, but instead
administrative methods for describing sets of configurations.
The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT", and "MAY"
in this document are to be interpreted as described in [RFC2119].
2. UI Suites
This section lists optional, non-mandatory suites that may be
presented to system administrators to ease the burden of choosing
among the many options in IPsec systems. These suites cannot cover
all of the options that an administrator needs to select. Instead,
they give values for a subset of the options.
Note that these UI suites are simply collections of values for some
options in IPsec. Use of UI suites does not change the IPsec, IKE,
or IKEv2 protocols in any way. Specifically, the transform
substructure in IKE and IKEv2 must be used to give the value for each
specified option regardless of whether or not UI suites are used.
Implementations that use UI suites SHOULD also provide a management
interface for specifying values for individual cryptographic options.
That is, it is unlikely that UI suites are a complete solution for
matching the security policies of many IPsec users, and therefore an
interface that gives a more complete set of options should be used as
IPsec implementations that use these UI suites SHOULD use the suite
names listed here. IPsec implementations SHOULD NOT use names
different than those listed here for the suites that are described,
and MUST NOT use the names listed here for suites that do not match
these values. These requirements are necessary for interoperability.
Note that the suites listed here are for use of IPsec in virtual
private networks. Other uses of IPsec will probably want to define
their own suites and give them different names.
Additional suites can be defined by RFCs. The strings used to
identify UI suites are registered by IANA.
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