--- 1/draft-ietf-ipsecme-qr-ikev2-10.txt 2020-01-14 22:13:12.426094239 -0800 +++ 2/draft-ietf-ipsecme-qr-ikev2-11.txt 2020-01-14 22:13:12.474095463 -0800 @@ -1,21 +1,21 @@ Internet Engineering Task Force S. Fluhrer -Internet-Draft D. McGrew -Intended status: Standards Track P. Kampanakis -Expires: June 29, 2020 Cisco Systems +Internet-Draft P. Kampanakis +Intended status: Standards Track D. McGrew +Expires: July 17, 2020 Cisco Systems V. Smyslov ELVIS-PLUS - December 27, 2019 + January 14, 2020 - Mixing Preshared Keys in IKEv2 for Post-quantum Resistance - draft-ietf-ipsecme-qr-ikev2-10 + Mixing Preshared Keys in IKEv2 for Post-quantum Security + draft-ietf-ipsecme-qr-ikev2-11 Abstract The possibility of quantum computers poses a serious challenge to cryptographic algorithms deployed widely today. IKEv2 is one example of a cryptosystem that could be broken; someone storing VPN communications today could decrypt them at a later time when a quantum computer is available. It is anticipated that IKEv2 will be extended to support quantum-secure key exchange algorithms; however that is not likely to happen in the near term. To address this @@ -31,25 +31,25 @@ 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 June 29, 2020. + This Internet-Draft will expire on July 17, 2020. Copyright Notice - Copyright (c) 2019 IETF Trust and the persons identified as the + Copyright (c) 2020 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 Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as @@ -66,87 +66,95 @@ 5. PPK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 5.1. PPK_ID format . . . . . . . . . . . . . . . . . . . . . . 12 5.2. Operational Considerations . . . . . . . . . . . . . . . 13 5.2.1. PPK Distribution . . . . . . . . . . . . . . . . . . 13 5.2.2. Group PPK . . . . . . . . . . . . . . . . . . . . . . 13 5.2.3. PPK-only Authentication . . . . . . . . . . . . . . . 14 6. Security Considerations . . . . . . . . . . . . . . . . . . . 14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 8.1. Normative References . . . . . . . . . . . . . . . . . . 17 - 8.2. Informational References . . . . . . . . . . . . . . . . 17 - Appendix A. Discussion and Rationale . . . . . . . . . . . . . . 18 - Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 19 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 + 8.2. Informational References . . . . . . . . . . . . . . . . 18 + Appendix A. Discussion and Rationale . . . . . . . . . . . . . . 19 + Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 20 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 1. Introduction Recent achievements in developing quantum computers demonstrate that it is probably feasible to build a cryptographically significant one. If such a computer is implemented, many of the cryptographic algorithms and protocols currently in use would be insecure. A quantum computer would be able to solve DH and ECDH problems in polynomial time [I-D.hoffman-c2pq], and this would imply that the security of existing IKEv2 [RFC7296] systems would be compromised. IKEv1 [RFC2409], when used with strong preshared keys, is not vulnerable to quantum attacks, because those keys are one of the inputs to the key derivation function. If the preshared key has sufficient entropy and the PRF, encryption and authentication transforms are quantum-secure, then the resulting system is believed - to be quantum resistant, that is, invulnerable to an attacker with a - quantum computer. + to be quantum-secure, that is, secure against classical attackers of + today or future attackers with a quantum computer. This document describes a way to extend IKEv2 to have a similar property; assuming that the two end systems share a long secret key, - then the resulting exchange is quantum resistant. By bringing post- - quantum security to IKEv2, this note removes the need to use an + then the resulting exchange is quantum-secure. By bringing post- + quantum security to IKEv2, this document removes the need to use an obsolete version of the Internet Key Exchange in order to achieve that security goal. The general idea is that we add an additional secret that is shared between the initiator and the responder; this secret is in addition to the authentication method that is already provided within IKEv2. We stir this secret into the SK_d value, which is used to generate the key material (KEYMAT) and the SKEYSEED for the child SAs; this secret provides quantum resistance to the IPsec SAs (and any child IKE SAs). We also stir the secret into the SK_pi, SK_pr values; this allows both sides to detect a secret mismatch cleanly. It was considered important to minimize the changes to IKEv2. The existing mechanisms to do authentication and key exchange remain in place (that is, we continue to do (EC)DH, and potentially PKI authentication if configured). This document does not replace the - authentication checks that the protocol does; instead, it is done as - a parallel check. + authentication checks that the protocol does; instead, they are + strengthened by using an additional secret key. 1.1. Changes RFC EDITOR PLEASE DELETE THIS SECTION. Changes in this draft in each version iterations. + draft-ietf-ipsecme-qr-ikev2-11 + + o Updates the IANA section based on Eric V.'s IESG Review. + + o Updates based on IESG Reviews (Alissa, Adam, Barry, Alexey, Mijra, + Roman, Martin. + draft-ietf-ipsecme-qr-ikev2-10 o Addresses issues raised during IETF LC. draft-ietf-ipsecme-qr-ikev2-09 o Addresses issues raised in AD review. draft-ietf-ipsecme-qr-ikev2-08 - o Editorial changes. draft-ietf-ipsecme-qr-ikev2-07 o Editorial changes. + draft-ietf-ipsecme-qr-ikev2-06 + o Editorial changes. draft-ietf-ipsecme-qr-ikev2-05 o Addressed comments received during WGLC. draft-ietf-ipsecme-qr-ikev2-04 o Using Group PPK is clarified based on comment from Quynh Dang. @@ -174,25 +182,25 @@ o Nits and minor fixes. o prf is replaced with prf+ for the SK_d and SK_pi/r calculations. o Clarified using PPK in case of EAP authentication. o PPK_SUPPORT notification is changed to USE_PPK to better reflect its purpose. - draft-ietf-ipsecme-qr-ikev2-00 - o Migrated from draft-fluhrer-qr-ikev2-05 to draft-ietf-ipsecme-qr- ikev2-00 that is a WG item. + draft-fluhrer-qr-ikev2-05 + o Nits and editorial fixes. o Made PPK_ID format and PPK Distributions subsection of the PPK section. Also added an Operational Considerations section. o Added comment about Child SA rekey in the Security Considerations section. o Added NO_PPK_AUTH to solve the cases where a PPK_ID is not configured for a responder. @@ -263,83 +270,87 @@ not used for any key derivation, and thus doesn't protect against quantum computers). The PPK specific configuration that is assumed to be on each node consists of the following tuple: Peer, PPK, PPK_ID, mandatory_or_not 3. Exchanges If the initiator is configured to use a post-quantum preshared key with the responder (whether or not the use of the PPK is mandatory), - then it will include a notification USE_PPK in the IKE_SA_INIT + then it MUST include a notification USE_PPK in the IKE_SA_INIT request message as follows: Initiator Responder ------------------------------------------------------------------ HDR, SAi1, KEi, Ni, N(USE_PPK) ---> N(USE_PPK) is a status notification payload with the type 16435; it has a protocol ID of 0, no SPI and no notification data associated with it. - If the initiator needs to resend this initial message with a cookie - (because the responder response included a COOKIE notification), then - the resend would include the USE_PPK notification if the original - message did. + If the initiator needs to resend this initial message with a COOKIE + notification, then the resend would include the USE_PPK notification + if the original message did (see Section 2.6 of [RFC7296]). If the responder does not support this specification or does not have any PPK configured, then it ignores the received notification (as defined in [RFC7296] for unknown status notifications) and continues with the IKEv2 protocol as normal. Otherwise the responder replies with the IKE_SA_INIT message including a USE_PPK notification in the response: Initiator Responder ------------------------------------------------------------------ <--- HDR, SAr1, KEr, Nr, [CERTREQ,] N(USE_PPK) When the initiator receives this reply, it checks whether the responder included the USE_PPK notification. If the responder did not and the flag mandatory_or_not indicates that using PPKs is mandatory for communication with this responder, then the initiator MUST abort the exchange. This situation may happen in case of - misconfiguration, when the initiator believes it has a mandatory to + misconfiguration, when the initiator believes it has a mandatory-to- use PPK for the responder, while the responder either doesn't support PPKs at all or doesn't have any PPK configured for the initiator. See Section 6 for discussion of the possible impacts of this situation. If the responder did not include the USE_PPK notification and using a PPK for this particular responder is optional, then the initiator continues with the IKEv2 protocol as normal, without using PPKs. If the responder did include the USE_PPK notification, then the initiator selects a PPK, along with its identifier PPK_ID. Then, it - computes this modification of the standard IKEv2 key derivation: + computes this modification of the standard IKEv2 key derivation from + Section 2.14 of [RFC7296]: SKEYSEED = prf(Ni | Nr, g^ir) {SK_d' | SK_ai | SK_ar | SK_ei | SK_er | SK_pi' | SK_pr' ) = prf+ (SKEYSEED, Ni | Nr | SPIi | SPIr } SK_d = prf+ (PPK, SK_d') SK_pi = prf+ (PPK, SK_pi') SK_pr = prf+ (PPK, SK_pr') That is, we use the standard IKEv2 key derivation process except that - the three subkeys SK_d, SK_pi, SK_pr are run through the prf+ again, - this time using the PPK as the key. Using prf+ construction ensures - that it is always possible to get the resulting keys of the same size - as the initial ones, even if the underlying PRF has output size - different from its key size. Note, that at the time this document - was written, all PRFs defined for use in IKEv2 [IKEV2-IANA-PRFS] had - output size equal to the (preferred) key size. For such PRFs only - the first iteration of prf+ is needed: + the three resulting subkeys SK_d, SK_pi, SK_pr (marked with primes in + the formula above) are then run through the prf+ again, this time + using the PPK as the key. The result is the unprimed versions of + these keys which are then used as inputs to subsequent steps of the + IKEv2 exchange. + + Using a prf+ construction ensures that it is always possible to get + the resulting keys of the same size as the initial ones, even if the + underlying PRF has output size different from its key size. Note, + that at the time of this writing, all PRFs defined for use in IKEv2 + [IKEV2-IANA-PRFS] had output size equal to the (preferred) key size. + For such PRFs only the first iteration of prf+ is needed: SK_d = prf (PPK, SK_d' | 0x01) SK_pi = prf (PPK, SK_pi' | 0x01) SK_pr = prf (PPK, SK_pr' | 0x01) Note that the PPK is used in SK_d, SK_pi and SK_pr calculation only during the initial IKE SA setup. It MUST NOT be used when these subkeys are calculated as result of IKE SA rekey, resumption or other similar operation. @@ -356,35 +367,38 @@ protocol ID of 0, no SPI and a notification data that consists of the identifier PPK_ID. A situation may happen when the responder has some PPKs, but doesn't have a PPK with the PPK_ID received from the initiator. In this case the responder cannot continue with PPK (in particular, it cannot authenticate the initiator), but the responder could be able to continue with normal IKEv2 protocol if the initiator provided its authentication data computed as in normal IKEv2, without using PPKs. For this purpose, if using PPKs for communication with this responder - is optional for the initiator, then the initiator MAY include a - notification NO_PPK_AUTH in the above message. + is optional for the initiator (based on the mandatory_or_not flag), + then the initiator MUST include a NO_PPK_AUTH notification in the + above message. This notification informs the responder that PPK is + optional and allows for authenticating the initiator without using + PPK. NO_PPK_AUTH is a status notification with the type 16437; it has a protocol ID of 0 and no SPI. The Notification Data field contains the initiator's authentication data computed using SK_pi', which has been computed without using PPKs. This is the same data that would normally be placed in the Authentication Data field of an AUTH payload. Since the Auth Method field is not present in the notification, the authentication method used for computing the authentication data MUST be the same as method indicated in the AUTH payload. Note that if the initiator decides to include the NO_PPK_AUTH notification, the initiator needs to perform authentication data computation twice, which may consume computation - power (e.g. if digital signatures are involved). + power (e.g., if digital signatures are involved). When the responder receives this encrypted exchange, it first computes the values: SKEYSEED = prf(Ni | Nr, g^ir) {SK_d' | SK_ai | SK_ar | SK_ei | SK_er | SK_pi' | SK_pr' } = prf+ (SKEYSEED, Ni | Nr | SPIi | SPIr ) The responder then uses the SK_ei/SK_ai values to decrypt/check the message and then scans through the payloads for the PPK_ID attached @@ -519,59 +534,55 @@ both peers have been upgraded, but the responder isn't yet configured with the PPK for the initiator, then the responder could do standard IKEv2 protocol if the initiator sent NO_PPK_AUTH notification. If both the responder and initiator have been upgraded and properly configured, they will both realize it, and the Child SAs will be quantum-secure. As an optional second step, after all nodes have been upgraded, then the administrator should then go back through the nodes, and mark the use of PPK as mandatory. This will not affect the strength against a - passive attacker; it would mean that an attacker with a quantum - computer (which is sufficiently fast to be able to break the (EC)DH - in real time) would not be able to perform a downgrade attack. + passive attacker, but it would mean that an active attacker with a + quantum computer (which is sufficiently fast to be able to break the + (EC)DH in real-time) would not be able to perform a downgrade attack. 5. PPK 5.1. PPK_ID format This standard requires that both the initiator and the responder have a secret PPK value, with the responder selecting the PPK based on the PPK_ID that the initiator sends. In this standard, both the initiator and the responder are configured with fixed PPK and PPK_ID values, and do the look up based on PPK_ID value. It is anticipated - that later standards will extend this technique to allow dynamically - changing PPK values. To facilitate such an extension, we specify - that the PPK_ID the initiator sends will have its first octet be the - PPK_ID Type value. This document defines two values for PPK_ID Type: + that later specifications will extend this technique to allow + dynamically changing PPK values. To facilitate such an extension, we + specify that the PPK_ID the initiator sends will have its first octet + be the PPK_ID Type value. This document defines two values for + PPK_ID Type: o PPK_ID_OPAQUE (1) - for this type the format of the PPK_ID (and the PPK itself) is not specified by this document; it is assumed to be mutually intelligible by both by initiator and the responder. This PPK_ID type is intended for those implementations that choose not to disclose the type of PPK to active attackers. o PPK_ID_FIXED (2) - in this case the format of the PPK_ID and the PPK are fixed octet strings; the remaining bytes of the PPK_ID are a configured value. We assume that there is a fixed mapping between PPK_ID and PPK, which is configured locally to both the initiator and the responder. The responder can use the PPK_ID to look up the corresponding PPK value. Not all implementations are able to configure arbitrary octet strings; to improve the potential interoperability, it is recommended that, in the PPK_ID_FIXED case, both the PPK and the PPK_ID strings be limited - to the base64 character set, namely the 64 characters 0-9, A-Z, - a-z, + and /. - - The PPK_ID type value 0 is reserved; values 3-127 are reserved for - IANA; values 128-255 are for private use among mutually consenting - parties. + to the Base64 character set [RFC4648]. 5.2. Operational Considerations The need to maintain several independent sets of security credentials can significantly complicate a security administrator's job, and can potentially slow down widespread adoption of this specification. It is anticipated, that administrators will try to simplify their job by decreasing the number of credentials they need to maintain. This section describes some of the considerations for PPK management. @@ -620,65 +631,65 @@ Combining group PPK and PPK-only authentication is NOT RECOMMENDED, since in this case any member of the group can impersonate any other member even without help of quantum computers. PPK-only authentication can be achieved in IKEv2 if the NULL Authentication method [RFC7619] is employed. Without PPK the NULL Authentication method provides no authentication of the peers, however since a PPK is stirred into the SK_pi and the SK_pr, the peers become authenticated if a PPK is in use. Using PPKs MUST be mandatory for the peers if they advertise support for PPK in - IKE_SA_INIT and use NULL Authentication. Addtionally, since the + IKE_SA_INIT and use NULL Authentication. Additionally, since the peers are authenticated via PPK, the ID Type in the IDi/IDr payloads SHOULD NOT be ID_NULL, despite using the NULL Authentication method. 6. Security Considerations Quantum computers are able to perform Grover's algorithm [GROVER]; that effectively halves the size of a symmetric key. Because of this, the user SHOULD ensure that the post-quantum preshared key used has at least 256 bits of entropy, in order to provide 128 bits of post-quantum security. That provides security equivalent to Level 5 as defined in the NIST PQ Project Call For Proposals [NISTPQCFP]. With this protocol, the computed SK_d is a function of the PPK. Assuming that the PPK has sufficient entropy (for example, at least 2^256 possible values), then even if an attacker was able to recover the rest of the inputs to the PRF function, it would be infeasible to use Grover's algorithm with a quantum computer to recover the SK_d value. Similarly, all keys that are a function of SK_d, which include all Child SAs keys and all keys for subsequent IKE SAs - (created when the initial IKE SA is rekeyed), are also quantum - resistant (assuming that the PPK was of high enough entropy, and that - all the subkeys are sufficiently long). + (created when the initial IKE SA is rekeyed), are also quantum-secure + (assuming that the PPK was of high enough entropy, and that all the + subkeys are sufficiently long). An attacker with a quantum computer that can decrypt the initial IKE SA has access to all the information exchanged over it, such as identities of the peers, configuration parameters and all negotiated IPsec SAs information (including traffic selectors), with the exception of the cryptographic keys used by the IPsec SAs which are protected by the PPK. Deployments that treat this information as sensitive or that send other sensitive data (like cryptographic keys) over IKE SA MUST rekey the IKE SA before the sensitive information is sent to ensure this information is protected by the PPK. It is possible to create a childless IKE SA as specified in [RFC6023]. This prevents Child SA - configuration information from being transmited in the original IKE + configuration information from being transmitted in the original IKE SA that is not protected by a PPK. Some information related to IKE SA, that is sent in the IKE_AUTH exchange, such as peer identities, feature notifications, Vendor ID's etc. cannot be hidden from the attack described above, even if the additional IKE SA rekey is performed. In addition, the policy SHOULD be set to negotiate only quantum- - resistant symmetric algorithms; while this RFC doesn't claim to give + secure symmetric algorithms; while this RFC doesn't claim to give advice as to what algorithms are secure (as that may change based on future cryptographical results), below is a list of defined IKEv2 and IPsec algorithms that should not be used, as they are known to provide less than 128 bits of post-quantum security o Any IKEv2 Encryption algorithm, PRF or Integrity algorithm with key size less than 256 bits. o Any ESP Transform with key size less than 256 bits. @@ -687,26 +698,29 @@ 128-bit key internally. Section 3 requires the initiator to abort the initial exchange if using PPKs is mandatory for it, but the responder does not include the USE_PPK notification in the response. In this situation, when the initiator aborts negotiation it leaves a half-open IKE SA on the responder (because IKE_SA_INIT completes successfully from the responder's point of view). This half-open SA will eventually expire and be deleted, but if the initiator continues its attempts to create IKE SA with a high enough rate, then the responder may consider it as - a Denial-of-Service attack and take protection measures (see + a Denial-of-Service (DoS) attack and take protection measures (see [RFC8019] for more detail). In this situation, it is RECOMMENDED - that the initiator caches the negative result of the negotiation for - some time and doesn't make attempts to create it again for some time, - because this is a result of misconfiguration and probably some re- - configuration of the peers is needed. + that the initiator caches the negative result of the negotiation and + doesn't make attempts to create it again for some time. This period + of time may vary, but it is believed that waiting for at least few + minutes will not cause the responder to treat it as DoS attack. + Note, that this situation would most likely be a result of + misconfiguration and some re-configuration of the peers would + probably be needed. If using PPKs is optional for both peers and they authenticate themselves using digital signatures, then an attacker in between, equipped with a quantum computer capable of breaking public key operations in real time, is able to mount downgrade attack by removing USE_PPK notification from the IKE_SA_INIT and forging digital signatures in the subsequent exchange. If using PPKs is mandatory for at least one of the peers or PSK is used for authentication, then the attack will be detected and the SA won't be created. @@ -714,53 +728,66 @@ If using PPKs is mandatory for the initiator, then an attacker able to eavesdrop and to inject packets into the network can prevent creating an IKE SA by mounting the following attack. The attacker intercepts the initial request containing the USE_PPK notification and injects a forged response containing no USE_PPK. If the attacker manages to inject this packet before the responder sends a genuine response, then the initiator would abort the exchange. To thwart this kind of attack it is RECOMMENDED, that if using PPKs is mandatory for the initiator and the received response doesn't contain the USE_PPK notification, then the initiator doesn't abort the - exchange immediately, but instead waits some time for more responses - (possibly retransmitting the request). If all the received responses - contain no USE_PPK, then the exchange is aborted. + exchange immediately. Instead it waits for more response messages + retransmitting the request as if no responses were received at all, + until either the received message contains the USE_PPK or the + exchange times out (see section 2.4 of [RFC7296] for more details + about retransmission timers in IKEv2). If neither of the received + responses contains USE_PPK, then the exchange is aborted. If using PPK is optional for both peers, then in case of - misconfiguration (e.g. mismatched PPK_ID) the IKE SA will be created + misconfiguration (e.g., mismatched PPK_ID) the IKE SA will be created without protection against quantum computers. It is advised that if PPK was configured, but was not used for a particular IKE SA, then implementations SHOULD audit this event. 7. IANA Considerations This document defines three new Notify Message Types in the "Notify - Message Types - Status Types" registry: + Message Types - Status Types" registry + (https://www.iana.org/assignments/ikev2-parameters/ + ikev2-parameters.xhtml#ikev2-parameters-16): 16435 USE_PPK [THIS RFC] 16436 PPK_IDENTITY [THIS RFC] 16437 NO_PPK_AUTH [THIS RFC] This document also creates a new IANA registry "IKEv2 Post-quantum Preshared Key ID Types" in IKEv2 IANA registry (https://www.iana.org/assignments/ikev2-parameters/) for the PPK_ID - types. The initial values of the new registry are: + types used in the PPK_IDENTITY notification defined in this + specification. The initial values of the new registry are: PPK_ID Type Value Reference ----------- ----- --------- Reserved 0 [THIS RFC] PPK_ID_OPAQUE 1 [THIS RFC] PPK_ID_FIXED 2 [THIS RFC] Unassigned 3-127 [THIS RFC] - Reserved for private use 128-255 [THIS RFC] - Changes and additions to this registry are by Expert Review - [RFC8126]. + Private Use 128-255 [THIS RFC] + + The PPK_ID type value 0 is reserved; values 3-127 are to be assigned + by IANA; values 128-255 are for private use among mutually consenting + parties. To register new PPK_IDs in the unassigned range, a Type + name, a Value between 3 and 127 and a Reference specification need to + be defined. Changes and additions to the unassigned range of this + registry are by the Expert Review Policy [RFC8126]. Changes and + additions to the private use range of this registry are by the + Private Use Policy [RFC8126]. 8. References 8.1. 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, . @@ -785,26 +812,32 @@ progress), November 2019. [IKEV2-IANA-PRFS] "Internet Key Exchange Version 2 (IKEv2) Parameters, Transform Type 2 - Pseudorandom Function Transform IDs", . [NISTPQCFP] NIST, "NIST Post-Quantum Cryptography Call for Proposals", - 2016. + 2016, . [RFC2409] Harkins, D. and D. Carrel, "The Internet Key Exchange (IKE)", RFC 2409, DOI 10.17487/RFC2409, November 1998, . + [RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data + Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006, + . + [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, . [RFC6030] Hoyer, P., Pei, M., and S. Machani, "Portable Symmetric Key Container (PSKC)", RFC 6030, DOI 10.17487/RFC6030, October 2010, . @@ -845,45 +878,45 @@ Another goal of this protocol is to minimize the number of changes within the IKEv2 protocol, and in particular, within the cryptography of IKEv2. By limiting our changes to notifications, and only adjusting the SK_d, SK_pi, SK_pr, it is hoped that this would be implementable, even on systems that perform most of the IKEv2 processing in hardware. A third goal was to be friendly to incremental deployment in operational networks, for which we might not want to have a global - shared key, or quantum resistant IKEv2 is rolled out incrementally. + shared key, or quantum-secure IKEv2 is rolled out incrementally. This is why we specifically try to allow the PPK to be dependent on the peer, and why we allow the PPK to be configured as optional. A fourth goal was to avoid violating any of the security properties provided by IKEv2. Appendix B. Acknowledgements We would like to thank Tero Kivinen, Paul Wouters, Graham Bartlett, Tommy Pauly, Quynh Dang and the rest of the IPSecME Working Group for their feedback and suggestions for the scheme. Authors' Addresses Scott Fluhrer Cisco Systems Email: sfluhrer@cisco.com - David McGrew + Panos Kampanakis Cisco Systems - Email: mcgrew@cisco.com + Email: pkampana@cisco.com - Panos Kampanakis + David McGrew Cisco Systems - Email: pkampana@cisco.com + Email: mcgrew@cisco.com Valery Smyslov ELVIS-PLUS Phone: +7 495 276 0211 Email: svan@elvis.ru