Using the Internet Key Exchange Protocol Version 2 (IKEv2) for PSP Key Management
draft-smyslov-ipsecme-ikev2-psp-00
This document is an Internet-Draft (I-D).
Anyone may submit an I-D to the IETF.
This I-D is not endorsed by the IETF and has no formal standing in the
IETF standards process.
| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Author | Valery Smyslov | ||
| Last updated | 2025-10-16 | ||
| RFC stream | (None) | ||
| Intended RFC status | (None) | ||
| Formats | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-smyslov-ipsecme-ikev2-psp-00
Network Working Group V. Smyslov
Internet-Draft ELVIS-PLUS
Intended status: Experimental 16 October 2025
Expires: 19 April 2026
Using the Internet Key Exchange Protocol Version 2 (IKEv2) for PSP Key
Management
draft-smyslov-ipsecme-ikev2-psp-00
Abstract
This document specifies how the Internet Key Exchange Version 2
(IKEv2) protocol can be used for supplying keys for the PSP Security
Protocol (PSP).
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 19 April 2026.
Copyright Notice
Copyright (c) 2025 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 (https://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. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Smyslov Expires 19 April 2026 [Page 1]
Internet-Draft IKEv2 for PSP Key Management October 2025
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology and Notation . . . . . . . . . . . . . . . . . . 2
3. PSP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
4. PSP Key Management Using IKEv2 . . . . . . . . . . . . . . . 3
4.1. The IKE_SA_INIT Exchange . . . . . . . . . . . . . . . . 3
4.2. The IKE_AUTH Exchange . . . . . . . . . . . . . . . . . . 4
4.3. The Modified CREATE_CHILD_SA Exchange . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
Internet Key Exchange Version 2 (IKEv2) protocol [RFC7296] is used in
IPsec architecture [RFC4301] for the purpose SA negotiation and key
management. It provides authenticated key exchange and calculates
session keys for the Encapsulating Security Payload (ESP) protocol
[RFC4303].
PSP Security Protocol (PSP) is defined in [PSP]. The protocol
utilizes the concept of so called "stateless encryption" by keeping
only global state for decrypting incoming packets. This concept
implies that the receiving side of Security Association (SA) provides
the sending side with a key at the time this SA is being created.
PSP is considered as an alternative for ESP for high-speed
communications (e.g., inside data centers). However, IKEv2 cannot
directly be used for providing keys for PSP, since the way IPsec keys
are being obtained in IKEv2 implies that they are derived from the
ephemeral key exchange and thus are unpredictable. This is
incompatible with the way keys are used in PSP where each side must
independently generate keys used for decryption for a particular SA
based on some global key.
2. Terminology and Notation
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Smyslov Expires 19 April 2026 [Page 2]
Internet-Draft IKEv2 for PSP Key Management October 2025
3. PSP
PSP [PSP] is a security protocol created by Google for encryption on
IP level. PSP was designed to address the high-speed encryption
requirements of large-scale data centers. To avoid storing per-SA
decryption keys on the receiver side, the decryption keys are derived
from the SPI (that is present in the packet) plus a global secret
known only to the receiver side.
PSP specification does not address key management issues. It assumes
that at the time an SA is being created the sender asks the receiver
to create an SA encryption key, which the receiver then somehow
communicates securely to the sender.
4. PSP Key Management Using IKEv2
IKEv2 cannot directly be used for providing keys for PSP, because its
specification [RFC7296] assumes that keying material for Child SAs is
derived using initial ephemeral key exchange. Thus, peers contribute
to this keying material, but cannot control it and for this reason
cannot provide each other with arbitrary keys.
On the other hand, IKEv2 extension for group key management
[I-D.ietf-ipsecme-g-ikev2] does allow this functionality as it is
needed for providing members of a group with identical keys. This
specification re-uses the ability to download arbitrary keys in IKEv2
from [I-D.ietf-ipsecme-g-ikev2]. Note that unlike
[I-D.ietf-ipsecme-g-ikev2] this specification is for unicast (peer-
to-peer) communication.
Since both peers have to provide each other with keying material, it
is not possible to do that in the IKE_AUTH exchange (as in
[RFC7296]), since the initiator in this case would send its key
(which is sensitive information) to the not-yet-authenticated
responder. For this reason, peers MUST create IKE SA childless as
specified in [RFC6023]. Once childless IKE SA is created, peers can
use the modified CREATE_CHILD_SA exchange to create or rekey Child
SAs utilizing PSP.
4.1. The IKE_SA_INIT Exchange
Peers wishing to use IKEv2 for providing keys for PSP MUST negotiate
the Key Wrap Algorithm (KWA) transform (Section 4.4.2.1.2 of
[I-D.ietf-ipsecme-g-ikev2]) in the IKE_SA_INIT exchange. If the
initiator is not sure that the responder supports PSP and if using
PSP is optional for the initiator, then the initiator MAY include two
proposals into the IKE_SA_INIT request - one with the Key Wrap
Algorithm transform (aiming for responders supporting PSP) and the
Smyslov Expires 19 April 2026 [Page 3]
Internet-Draft IKEv2 for PSP Key Management October 2025
other without it.
The responder supporting PSP key management, besides negotiation of
the KWA transform, MUST also include the CHILDLESS_IKEV2_SUPPORTED
notification (Section 4 of [RFC6023]) in the IKE_SA_INIT response.
Even if the KWA transform is negotiated, it does not mean that this
IKE SA is for creating PSP SAs only - such an SA MAY be used for
creating both ESP and PSP SAs.
4.2. The IKE_AUTH Exchange
The PSP Child SA cannot be created in the IKE_AUTH exchange. On the
other hand, peers may create the ESP Child SA in this exchange if
they want to. Otherwise, the IKE SA is created childless and the
IKE_AUTH exchange is as defined in Section 5 of [RFC6023].
4.3. The Modified CREATE_CHILD_SA Exchange
Modified CREATE_CHILD_SA exchange is used for creating the PSP SA.
The following modifications are made.
* The SA payload MUST contain one or more Proposal substructures
with the Protocol ID field set to a new Security Protocol
Identifier PSP (<TBA by IANA>). Note that SPI Size for PSP is the
same as for ESP (4 octets). Proposals with other Security
Protocol Identifiers MUST NOT be present.
* These Proposal substructures MUST only contain one or more
Transform substructures with new Transform Type "PSP Parameters
(PSP)" (<TBA by IANA>). See Section 6, Paragraph 2, Item 1 for
Possible Transform IDs for this Transform Type. Transform
substructures with other Transform Types MUST NOT be present.
* The CREATE_CHILD_SA messages MUST NOT contain the Key Exchange
(KE) and the Nonce (Ni and Nr) payloads. Instead, both request
and response MUST contain exactly one Key Download (KD) payload,
defined in Section 4.5 of [I-D.ietf-ipsecme-g-ikev2]. The sender
of a KD payload provides a keying material for the PSP SA that it
will use as a receiver to its peer.
* The KD payloads MUST contain exactly one or more Group Key Bag
substructure, defined in Section 4.5.2 of
[I-D.ietf-ipsecme-g-ikev2]. The Protocol field of this
substructures MUST be set to Security Protocol Identifier PSP
(<TBA by IANA>), the SPI MUST match that in one of the Proposal
substructures in the SA payload.
Smyslov Expires 19 April 2026 [Page 4]
Internet-Draft IKEv2 for PSP Key Management October 2025
* Each Key Bag MUST contain exactly one SA_KEY attribute, defined in
Section 4.5.2.1 of [I-D.ietf-ipsecme-g-ikev2], in which the
wrapped keying material (See Section 4.5.4 of
[I-D.ietf-ipsecme-g-ikev2]) for the PSP SA is provided. The Key
ID and the KWK ID fields MUST be set to zero, meaning that this
attribute contains the keying material for an SA and this keying
material is protected with the default Key Wrap Key SK_w that is
calculated as
SK_w = prf+(SK_d, "Key Wrap for PSP")
* The size of the provided keying material MUST be sufficient to get
keys for any of the proposed PSP parameters.
The modified CREATE_CHILD_SA exchange is shown below.
Initiator Responder
------------------------------------------------------------------
HDR, SK {[N(REKEY_SA),]
SA, KD, TSi, TSr} --->
<--- HDR, SK {SA, KD, TSi, TSr}
Figure 1: CREATE_CHILD_SA Exchange for PSP
The USE_TRANSPORT_MODE notification can be used in case of PSP to
indicate that the PSP SA is to be created using transport mode, as
with ESP.
The REKEY_SA notification can be present and plays the same role as
with ESP SA - indicates the SA to be replaced with a newly created
SA.
5. Security Considerations
To be added.
6. IANA Considerations
This document requests IANA to make the following changes in the
"Internet Key Exchange Version 2 (IKEv2) Parameters" registry group
[IKEV2-IANA].
1. Create new registry "Transform Type <TBA> - PSP Parameters
Transform IDs". The registration policy for this registry is
Expert Review Policy [RFC8126]. The initial values of the new
registry are:
Smyslov Expires 19 April 2026 [Page 5]
Internet-Draft IKEv2 for PSP Key Management October 2025
Value PSP Parameters
------------------------------------------
0 Reserved
1 PSP Header Version 0, AES-GCM-128
2 PSP Header Version 0, AES-GCM-256
3 PSP Header Version 0, AES-GMAC-128
4 PSP Header Version 0, AES-GMAC-256
Unassigned 5-1023
Private Use 1024-65535
2. Add new Transform Type "PSP Parameters (PSP)" in the "Transform
Type Values" registry.
Type Description Used In
---------------------------------------------------
<TBA> PSP Parameters (PSP) (PSP)
3. Add new Security Protocol Identifier in the "IKEv2 Security
Protocol Identifiers" registry.
Protocol ID Protocol
--------------------------
<TBA> PSP
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC7296] Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
Kivinen, "Internet Key Exchange Protocol Version 2
(IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
2014, <https://www.rfc-editor.org/info/rfc7296>.
Smyslov Expires 19 April 2026 [Page 6]
Internet-Draft IKEv2 for PSP Key Management October 2025
[RFC6023] Nir, Y., Tschofenig, H., Deng, H., and R. Singh, "A
Childless Initiation of the Internet Key Exchange Version
2 (IKEv2) Security Association (SA)", RFC 6023,
DOI 10.17487/RFC6023, October 2010,
<https://www.rfc-editor.org/info/rfc6023>.
[I-D.ietf-ipsecme-g-ikev2]
Smyslov, V. and B. Weis, "Group Key Management using
IKEv2", Work in Progress, Internet-Draft, draft-ietf-
ipsecme-g-ikev2-23, 31 July 2025,
<https://datatracker.ietf.org/doc/html/draft-ietf-ipsecme-
g-ikev2-23>.
[PSP] "PSP Architecture Specification", November 2022,
<https://github.com/google/psp/blob/main/doc/
PSP_Arch_Spec.pdf>.
7.2. Informative References
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <https://www.rfc-editor.org/info/rfc4301>.
[RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)",
RFC 4303, DOI 10.17487/RFC4303, December 2005,
<https://www.rfc-editor.org/info/rfc4303>.
[IKEV2-IANA]
IANA, "Internet Key Exchange Version 2 (IKEv2)
Parameters", <http://www.iana.org/assignments/ikev2-
parameters/ikev2-parameters.xhtml>.
Author's Address
Valery Smyslov
ELVIS-PLUS
Russian Federation
Email: [email protected]
Smyslov Expires 19 April 2026 [Page 7]