One document matched: draft-ietf-ipsecme-rfc4307bis-04.xml
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<rfc ipr="trust200902" docName="draft-ietf-ipsecme-rfc4307bis-04" category="std">
<front>
<title abbrev="IKEv2 Cryptographic Algorithms">Algorithm Implementation Requirements and Usage Guidance for IKEv2</title>
<author initials="Y." surname="Nir" fullname="Yoav Nir">
<organization abbrev="Check Point">Check Point Software Technologies Ltd.</organization>
<address>
<postal>
<street>5 Hasolelim st.</street>
<city>Tel Aviv</city>
<code>6789735</code>
<country>Israel</country>
</postal>
<email>ynir.ietf@gmail.com</email>
</address>
</author>
<author initials='T.' surname='Kivinen' fullname='Tero Kivinen'>
<organization>INSIDE Secure</organization>
<address>
<postal>
<street>Eerikinkatu 28</street>
<code>FI-00180</code>
<city>HELSINKI</city>
<country>FI</country>
</postal>
<email>kivinen@iki.fi</email>
</address>
</author>
<author fullname="Paul Wouters" initials="P." surname="Wouters">
<organization>Red Hat</organization>
<address>
<postal>
<street/>
<city/>
<region/>
<code/>
<country/>
</postal>
<email>pwouters@redhat.com</email>
</address>
</author>
<author fullname="Daniel Migault" initials="D." surname="Migault">
<organization> Ericsson </organization>
<address>
<postal>
<street> 8400 boulevard Decarie </street>
<city> Montreal, QC </city>
<code> H4P 2N2 </code>
<country> Canada </country>
</postal>
<phone> +1 514-452-2160 </phone>
<email> daniel.migault@ericsson.com </email>
</address>
</author>
<date year="2016"/>
<area>Security</area>
<!-- <workgroup>IPSecME Working Group</workgroup> -->
<keyword>Internet-Draft</keyword>
<abstract>
<t> The IPsec series of protocols makes use of various cryptographic algorithms in order to
provide security services. The Internet Key Exchange (IKE) protocol is used to negotiate
the IPsec Security Association (IPsec SA) parameters, such as which algorithms should be
used. To ensure interoperability between different implementations, it is necessary to
specify a set of algorithm implementation requirements and usage guidance to ensure that
there is at least one algorithm that all implementations support. This document defines the
current algorithm implementation requirements and usage guidance for IKEv2. This document
does not update the algorithms used for packet encryption using IPsec Encapsulated Security
Payload (ESP)</t>
</abstract>
</front>
<middle>
<!-- ====================================================================== -->
<section anchor="introduction" title="Introduction">
<t> The Internet Key Exchange (IKE) protocol <xref target="RFC7296" /> is used to negotiate
the parameters of the IPsec SA, such as the encryption and authentication algorithms and
the keys for the protected communications between the two endpoints. The IKE protocol itself
is also protected by encryption which is negotiated between the two endpoints using IKE.
Different implementations of IKE may negotiate different algorithms based on their individual
local policy. To ensure interoperability, a set of "mandatory-to-implement" IKE encryption
algorithms is defined.</t>
<t> This document describes the parameters of the IKE protocol. It does not describe the
cryptographic parameters of the AH or ESP protocols. </t>
<section title="Updating Algorithm Implementation Requirements and Usage Guidance">
<t> The field of cryptography evolves continuously. New stronger algorithms appear and
existing algorithms are found to be less secure then originally thought. Therefore,
algorithm implementation requirements and usage guidance need to be updated from time to
time to reflect the new reality. The choices for algorithms must be conservative to minimize
the risk of algorithm compromise. Algorithms need to be suitable for a wide variety of CPU
architectures and device deployments ranging from high end bulk encryption devices to small
low-power IoT devices.</t>
<t> The algorithm implementation requirements and usage guidance may need to change over time
to adapt to the changing world. For this reason, the selection of mandatory-to-implement
algorithms was removed from the main IKEv2 specification and placed in this document. </t>
</section>
<section title="Updating Algorithm Requirement Levels">
<t>The mandatory-to-implement algorithm of tomorrow should already be available in most
implementations of IKE by the time it is made mandatory. This document attempts to identify
and introduce those algorithms for future mandatory-to-implement status. There is no guarantee
that the algorithms in use today may become mandatory in the future. Published algorithms are
continuously subjected to cryptographic attack and may become too weak or could become
completely broken before this document is updated.</t>
<t> This document only provides recommendations for the mandatory-to-implement algorithms or
algorithms too weak that are recommended not to be implemented. As a result, any algorithm
listed at the IKEv2 IANA registry not mentioned in this document MAY be implemented. For
clarification and consistency with <xref target="RFC4307"/> an algorithm will be set to MAY
only when it has been downgraded.</t>
<t> Although this document updates the algorithms to keep the IKEv2 communication secure over
time, it also aims at providing recommendations so that IKEv2 implementations remain
interoperable. IKEv2 interoperability is addressed by an incremental introduction or
deprecation of algorithms. In addition, this document also considers the new use cases for
IKEv2 deployment, such as Internet of Things (IoT).</t>
<t> It is expected that deprecation of an algorithm is performed gradually. This provides time
for various implementations to update their implemented algorithms while remaining
interoperable. Unless there are strong security reasons, an algorithm is expected to be
downgraded from MUST to MUST- or SHOULD, instead of MUST NOT. Similarly, an algorithm that has
not been mentioned as mandatory-to-implement is expected to be introduced with a SHOULD instead
of a MUST.</t>
<t>The current trend toward Internet of Things and its adoption of IKEv2 requires this specific
use case to be taken into account as well. IoT devices are resource constrained devices and
their choice of algorithms are motivated by minimizing the footprint of the code, the
computation effort and the size of the messages to send. This document indicates "[IoT]" when a
specified algorithm is specifically listed for IoT devices.</t>
</section>
<section title="Document Audience">
<t>The recommendations of this document mostly target IKEv2 implementers as implementations
need to meet both high security expectations as well as high interoperability between various
vendors and with different versions. Interoperability requires a smooth move to more secure
cipher suites. This may differ from a user point of view that may deploy and configure IKEv2
with only the safest cipher suite. On the other hand, comments and recommendations from this
document are also expected to be useful for such users.</t>
<t> IKEv1 is out of scope of this document. IKEv1 is deprecated and the recommendations of this
document must not be considered for IKEv1, as most IKEv1 implementations have been "frozen"
and will not be able to update the list of mandatory-to-implement algorithms.</t>
</section>
</section>
<section anchor="mustshouldmay" title="Conventions Used in This Document">
<t> The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT",
"RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in
<xref target="RFC2119"/>.</t>
<t> We define some additional terms here:</t>
<texttable anchor="tbl" style="none" suppress-title="true">
<ttcol align="left" width="12%"/>
<ttcol align="left" />
<c>SHOULD+</c><c>This term means the same as SHOULD. However, it is likely that an algorithm
marked as SHOULD+ will be promoted at some future time to be a MUST.</c>
<c>SHOULD-</c><c>This term means the same as SHOULD. However, an algorithm marked as SHOULD-
may be deprecated to a MAY in a future version of this document.</c>
<c>MUST-</c><c>This term means the same as MUST. However, we expect at some point that this
algorithm will no longer be a MUST in a future document. Although its status will be
determined at a later time, it is reasonable to expect that if a future revision of a
document alters the status of a MUST- algorithm, it will remain at least a SHOULD or a
SHOULD- level.</c>
<c>IoT</c><c>stands for Internet of Things.</c>
</texttable>
</section>
<section anchor="algs" title="Algorithm Selection">
<section anchor="algs_enc" title="Type 1 - IKEv2 Encryption Algorithm Transforms">
<t> The algorithms in the below table are negotiated in the SA payload and used for the
Encrypted Payload. References to the specification defining these algorithms and the
ones in the following subsections are in the IANA registry <xref target="IKEV2-IANA"/>.
Some of these algorithms are Authenticated Encryption with Associated Data
(AEAD - <xref target="RFC5282" />). Algorithms that are not AEAD MUST be used in
conjunction with an integrity algorithms in <xref target="algs_integ"/>.</t>
<texttable anchor="tbl_enc" suppress-title="true">
<ttcol align="left">Name</ttcol>
<ttcol align="left">Status</ttcol>
<ttcol>AEAD?</ttcol>
<ttcol align="left">Comment</ttcol>
<c>ENCR_AES_CBC</c><c>MUST-</c><c>No</c><c>[1]</c>
<c>ENCR_CHACHA20_POLY1305</c><c>SHOULD</c><c>Yes</c><c/>
<c>AES-GCM with a 16 octet ICV</c><c>SHOULD</c><c>Yes</c><c>[1]</c>
<c>ENCR_AES_CCM_8</c><c>SHOULD</c><c>Yes</c><c>[1][IoT]</c>
<c>ENCR_3DES</c><c>MAY</c><c>No</c><c/>
<c>ENCR_DES</c><c>MUST NOT</c><c>No</c><c/>
<postamble>
[1] - This requirement level is for 128-bit keys. 256-bit keys are at MAY. 192-bit keys can
safely be ignored.
[IoT] - This requirement is for interoperability with IoT.
</postamble>
</texttable>
<t> ENCR_AES_CBC is raised from SHOULD+ in <xref target="RFC4307"/> to MUST. It is the only
shared mandatory-to-implement algorithm with RFC4307 and as a result it is necessary for
interoperability with IKEv2 implementation compatible with RFC4307.</t>
<t> ENCR_CHACHA20_POLY1305 was not ready to be considered at the time of RFC4307. It has been
recommended by the CRFG and others as an alternative to AES-CBC and AES-GCM. It is also being
standardized for IPsec for the same reasons. At the time of writing, there were not enough
IKEv2 implementations supporting ENCR_CHACHA20_POLY1305 to be able to introduce it at the
SHOULD+ level.</t>
<t> AES-GCM with a 16 octet ICV was not considered as in RFC4307. At the time RFC4307 was
written, AES-GCM was not defined in an IETF document. AES-GCM was defined for ESP in
<xref target="RFC4106"/> and later for IKEv2 in <xref target="RFC5282"/>. The main motivation
for adopting AES-GCM for ESP is encryption performance and key longevity compared to AES-CBC.
This resulted in AES-GCM being widely implemented for ESP. As the computation load of IKEv2 is
relatively small compared to ESP, many IKEv2 implementations have not implemented AES-GCM. For
this reason, AES-GCM is not promoted to a greater status than SHOULD. The reason for promotion
from MAY to SHOULD is to promote the slightly more secure AEAD method over the traditional
encrypt+auth method. Its status is expected to be raised once widely implemented. As the
advantage of the shorter (and weaker) ICVs is minimal, the 8 and 12 octet ICV's remain at
the MAY level.</t>
<t> ENCR_AES_CCM_8 was not considered in RFC4307. This document considers it as SHOULD be
implemented in order to be able to interact with Internet of Things devices. As this case
is not a general use case for non-IoT VPNs, its status is expected to remain as SHOULD.
The 8 octet size of the ICV is expected to be sufficient for most use cases of IKEv2, as
far less packets are exchanged on the IKE SA compared to the IPsec SA. When implemented,
ENCR_AES_CCM_8 MUST be implemented for key length 128 and MAY be implemented for key length
256.</t>
<t> ENCR_3DES has been downgraded from RFC4307 MUST- to SHOULD NOT. All IKEv2 implementation
already implement ENCR_AES_CBC, so there is no need to keep support for the much slower
ENCR_3DES. In addition, ENCR_CHACHA20_POLY1305 provides a more modern alternative to AES.</t>
<t> ENCR_DES can be brute-forced using of-the-shelves hardware. It provides no meaningful
security whatsoever and therefor MUST NOT be implemented.</t>
</section>
<section anchor="algs_prf" title="Type 2 - IKEv2 Pseudo-random Function Transforms">
<t> Transform Type 2 Algorithms are pseudo-random functions used to generate random values
when needed.</t>
<t> If an algorithm is selected as the integrity algorithm, it SHOULD also be used as the
PRF. When using an AEAD cipher, a choice of PRF needs to be made. The table below lists
the recommended algorithms.</t>
<texttable anchor="tbl_alg2" suppress-title="true">
<ttcol align="left">Name</ttcol>
<ttcol align="left">Status</ttcol>
<ttcol align="left">Comment</ttcol>
<c>PRF_HMAC_SHA2_256</c><c>MUST</c><c></c>
<c>PRF_HMAC_SHA2_512</c><c>SHOULD+</c><c></c>
<c>PRF_HMAC_SHA1</c><c>MUST-</c><c></c>
<c>PRF_AES128_CBC</c><c>SHOULD</c><c>[IoT]</c>
<c>PRF_HMAC_MD5</c><c>MUST NOT</c><c></c>
<postamble>
[IoT] - This requirement is for interoperability with IoT
</postamble>
</texttable>
<t> PRF_HMAC_SHA2_256 was not mentioned in RFC4307, as no SHA2 based authentication was
mentioned. PRF_HMAC_SHA2_256 MUST be implemented in order to replace SHA1 and
PRF_HMAC_SHA1.</t>
<t> PRF_HMAC_SHA2_512 SHOULD be implemented as a future replacement for PRF_HMAC_SHA2_256
or for when stronger security is required. PRF_HMAC_SHA2_512 is preferred over
PRF_HMAC_SHA2_384, as the additional overhead of PRF_HMAC_SHA2_512 is negligible.</t>
<t> PRF_HMAC_SHA1 has been downgraded from MUST in RFC4307 to MUST- as their is an
industry-wide trend to deprecate its usage.</t>
<t> PRF_AES128_CBC is only recommended in the scope of IoT, as Internet of Things deployments
tend to prefer AES based pseudo-random functions in order to avoid implementing SHA2. For
the non-IoT VPN deployment it has been downgraded from SHOULD in RFC4307 to MAY as it has
not seen wide adoption.</t>
<t>PRF_HMAC_MD5 has been downgraded from MAY in RFC4307 to MUST NOT. There is an industry-wide
trend to deprecate its usage as MD5 support is being removed from cryptographic libraries in
general because its non-HMAC use is known to be subject to collision attacks, for example as
mentioned in <xref target="TRANSCRIPTION"/>.</t>
</section>
<section anchor="algs_integ" title="Type 3 - IKEv2 Integrity Algorithm Transforms">
<t> The algorithms in the below table are negotiated in the SA payload and used for the
Encrypted Payload. References to the specification defining these algorithms are in the
IANA registry. When an AEAD algorithm (see <xref target="algs_enc"/>) is proposed, this
algorithm transform type is not in use.</t>
<texttable anchor="tbl_alg3" suppress-title="true">
<ttcol align="left">Name</ttcol>
<ttcol align="left">Status</ttcol>
<ttcol align="left">Comment</ttcol>
<c>AUTH_HMAC_SHA2_256_128</c><c>MUST</c><c></c>
<c>AUTH_HMAC_SHA2_512_256</c><c>SHOULD</c><c></c>
<c>AUTH_HMAC_SHA1_96</c><c>MUST-</c><c></c>
<c>AUTH_AES_XCBC_96</c><c>SHOULD</c><c>[IoT]</c>
<c>AUTH_HMAC_MD5_96</c><c>MUST NOT</c><c></c>
<c>AUTH_DES_MAC</c><c>MUST NOT</c><c></c>
<c>AUTH_KPDK_MD5</c><c>MUST NOT</c><c></c>
<postamble>
[IoT] - This requirement is for interoperability with IoT
</postamble>
</texttable>
<t> AUTH_HMAC_SHA2_256_128 was not mentioned in RFC4307, as no SHA2 based authentication was
mentioned. AUTH_HMAC_SHA2_256_128 MUST be implemented in order to replace AUTH_HMAC_SHA1_96.</t>
<t> AUTH_HMAC_SHA2_512_256 SHOULD be implemented as a future replacement of AUTH_HMAC_SHA2_256_128
or for when stronger security is required. This value has been preferred over AUTH_HMAC_SHA2_384,
as the additional overhead of AUTH_HMAC_SHA2_512 is negligible.</t>
<t> AUTH_HMAC_SHA1_96 has been downgraded from MUST in RFC4307 to MUST- as there is an
industry-wide trend to deprecate its usage.</t>
<t> AUTH_AES-XCBC is only recommended in the scope of IoT, as Internet of Things deployments tend
to prefer AES based pseudo-random functions in order to avoid implementing SHA2. For the non-IoT
VPN deployment, it has been downgraded from SHOULD in RFC4307 to MAY as it has not been widely
adopted. </t>
<t> AUTH_HMAC_MD5_96, AUTH_DES_MAC and AUTH_KPDK_MD5 were not mentioned in RFC4307 so its
default status was MAY. It has been downgraded to MUST NOT. There is an industry-wide trend
to deprecate its usage. MD5 support is being removed from cryptographic libraries in general
because its non-HMAC use is known to be subject to collision attacks, for example as
mentioned in <xref target="TRANSCRIPTION"/>.</t>
</section>
<section anchor="algs_dh" title="Type 4 - IKEv2 Diffie-Hellman Group Transforms">
<t> There are several Modular Exponential (MODP) groups and several Elliptic Curve groups
(ECC) that are defined for use in IKEv2. These groups are defined in both the [IKEv2] base
document and in extensions documents and are identified by group number. Note that it is
critical to enforce a secure Diffie Hellman exchange as this exchange provides encryption
for the session. If an attacker can retrieve the private numbers (for example a, b) (and?
or?) the public values (for example g**a, g**b), then the attacker can compute the secret
and the keys used and decrypt the exchange. Such an attack can be performed off-line on a
previously recorded communication, years after the communication happened. This differs
from attacks that need to be executed during the authentication which must be performed
online and in near real-time.</t>
<texttable anchor="tbl_dh" suppress-title="true">
<ttcol align="left">Number</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Status</ttcol>
<c>14</c><c>2048-bit MODP Group</c><c>MUST</c>
<c>19</c><c>256-bit random ECP group</c><c>SHOULD</c>
<c>5</c><c>1536-bit MODP Group</c><c>SHOULD NOT</c>
<c>2</c><c>1024-bit MODP Group</c><c>SHOULD NOT</c>
<c>1</c><c>768-bit MODP Group</c><c>MUST NOT</c>
<c>22</c><c>1024-bit MODP Group with 160-bit Prime Order Subgroup</c><c>SHOULD NOT</c>
<c>23</c><c>2048-bit MODP Group with 224-bit Prime Order Subgroup</c><c>SHOULD NOT</c>
<c>24</c><c>2048-bit MODP Group with 256-bit Prime Order Subgroup</c><c>SHOULD NOT</c>
</texttable>
<t> Group 14 or 2048-bit MODP Group is raised from SHOULD+ in RFC4307 as a replacement for
1024-bit MODP Group. Group 14 is widely implemented and considered secure.</t>
<t> Group 19 or 256-bit random ECP group was not specified in RFC4307, as this group were
not specified at that time. Group 19 is widely implemented and considered secure.</t>
<t> Group 5 or 1536-bit MODP Group has been downgraded from MAY in RFC4307 to SHOULD NOT.
It was specified earlier, but is now considered to be vulnerable to be broken within the
next few years by a nation state level attack, so its security margin is considered too
narrow.</t>
<t> Group 2 or 1024-bit MODP Group has been downgraded from MUST- in RFC4307 to SHOULD NOT.
It is known to be weak against sufficiently funded attackers using commercially available
mass-computing resources, so its security margin is considered too narrow. It is expected
in the near future to be downgraded to MUST NOT.</t>
<t> Group 1 or 768-bit MODP Group was not mentioned in RFC4307 and so its status was MAY.
It can be broken within hours using cheap of-the-shelves hardware. It provides no security
whatsoever.</t>
<t> Group 22, 23 and 24 or 1024-bit MODP Group with 160-bit, and 2048-bit MODP Group with
224-bit and 256-bit Prime Order Subgroup have small subgroups, which means that checks
specified in the "Additional Diffie-Hellman Test for the IKEv2" <xref target="RFC6989"/>
section 2.2 first bullet point MUST be done when these groups are used. These groups are
also not safe-primes. The seeds for these groups have not been publicly released, resulting
in reduced trust in these groups. These groups were proposed as alternatives for group 2
and 14 but never saw wide deployment. It is expected in the near future to be further
downgraded to MUST NOT.</t>
</section>
</section>
<section title="IKEv2 Authentication">
<t>IKEv2 authentication may involve a signatures verification. Signatures may be used to
validate a certificate or to check the signature of the AUTH value. Cryptographic
recommendations regarding certificate validation are out of scope of this document. What is
mandatory to implement is provided by the PKIX Community. This document is mostly concerned
on signature verification and generation for the authentication.</t>
<section anchor="auth" title="IKEv2 Authentication Method">
<texttable anchor="tbl_auth" suppress-title="true">
<ttcol align="left">Number</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Status</ttcol>
<c>1</c><c>RSA Digital Signature</c><c>MUST</c>
<c>3</c><c>DSS Digital Signature</c><c>SHOULD NOT</c>
<c>9</c><c>ECDSA with SHA-256 on the P-256 curve</c><c>SHOULD</c>
<c>10</c><c>ECDSA with SHA-384 on the P-384 curve</c><c>SHOULD</c>
<c>11</c><c>ECDSA with SHA-512 on the P-521 curve</c><c>SHOULD</c>
<c>14</c><c>Digital Signature</c><c>SHOULD</c>
</texttable>
<t> RSA Digital Signature is widely deployed and therefor kept for interoperability. It is
expected to be downgraded in the future as its signatures are based on the older
RSASSA-PKCS1-v1.5 which is no longer recommended. RSA authentication, as well as other
specific Authentication Methods, are expected to be replaced with the generic Digital
Signature method of <xref target="RFC7427"/>. RSA Digital Signature is not recommended
for keys smaller then 2048, but since these signatures only have value in real-time,
and need no future protection, smaller keys was kept at SHOULD NOT instead of MUST NOT.</t>
<t> ECDSA based Authentication Methods are also expected to be downgraded as it does not
provide hash function agility. Instead, ECDSA (like RSA) is expected to be performed using
the generic Digital Signature method.</t>
<t> DSS Digital Signature is bound to SHA-1 and has the same level of security as 1024-bit
RSA. It is expected to be downgraded to MUST NOT in the future.</t>
<t> Digital Signature <xref target="RFC7427"/> is expected to be promoted as it provides
hash function, signature format and algorithm agility.</t>
<section anchor="auth_rsa" title="Recommendations for RSA key length">
<texttable anchor="tbl_auth_keysize" suppress-title="true">
<ttcol align="left">Description</ttcol>
<ttcol align="left">Status</ttcol>
<c>RSA with key length 2048</c><c>MUST</c>
<c>RSA with key length 3072 and 4096</c><c>SHOULD</c>
<c>RSA with key length between 2049 and 4095</c><c>MAY</c>
<c>RSA with key length smaler than 2048</c><c>SHOULD NOT</c>
</texttable>
</section>
</section>
<section title="Digital Signature Recommendations">
<t>Recommendations for when a hash function is involved in a signature:</t>
<texttable anchor="tbl_hash" suppress-title="true">
<ttcol align="left">Number</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Status</ttcol>
<ttcol align="left">Comment</ttcol>
<c>1</c><c>SHA1</c><c>SHOULD NOT</c><c></c>
<c>2</c><c>SHA2-256</c><c>MUST</c><c></c>
<c>3</c><c>SHA2-384</c><c>MAY</c><c></c>
<c>4</c><c>SHA2-512</c><c>SHOULD</c><c></c>
</texttable>
<t>With the use of Digital Signature, RSASSA-PKCS1-v1.5 MAY be implemented. RSASSA-PSS MUST be implemented.</t>
<t>Recommendation of Authentication Method described in <xref target="RFC7427"/> notation:</t>
<texttable anchor="tbl_auth_methods_apply" suppress-title="true">
<ttcol align="left">Description</ttcol>
<ttcol align="left">Status</ttcol>
<ttcol align="left">Comment</ttcol>
<c>RSASSA-PSS with SHA-256</c><c>SHOULD</c><c></c>
<c>ecdsa-with-sha256</c><c>SHOULD</c><c></c>
<c>sha1WithRSAEncryption</c><c>SHOULD NOT</c><c></c>
<c>dsa-with-sha1</c><c>SHOULD NOT</c><c></c>
<c>ecdsa-with-sha1</c><c>SHOULD NOT</c><c></c>
<c>RSASSA-PSS with Empty Parameters</c><c>SHOULD NOT</c><c></c>
<c>RSASSA-PSS with Default Parameters</c><c>SHOULD NOT</c><c></c>
<c>sha256WithRSAEncryption</c><c>MAY</c><c></c>
<c>sha384WithRSAEncryption</c><c>MAY</c><c></c>
<c>sha512WithRSAEncryption</c><c>MAY</c><c></c>
<c>sha512WithRSAEncryption</c><c>MAY</c><c></c>
<c>dsa-with-sha256</c><c>MAY</c><c></c>
<c>ecdsa-with-sha384</c><c>MAY</c><c></c>
<c>ecdsa-with-sha512</c><c>MAY</c><c>?SHOULD</c>
</texttable>
</section>
</section>
<section anchor="security" title="Security Considerations">
<t> The security of cryptographic-based systems depends on both the strength of the
cryptographic algorithms chosen and the strength of the keys used with those algorithms.
The security also depends on the engineering of the protocol used by the system to ensure
that there are no non-cryptographic ways to bypass the security of the overall system.</t>
<t> The Diffie-Hellman Group parameter is the most important one to choose conservatively.
Any party capturing all IKE and ESP traffic that (even years later) can break the selected
DH group in IKE, can gain access to the symmetric keys used to encrypt all the ESP traffic.
Therefore, these groups must be chosen very conservatively. However, specifying an extremely
large DH group also puts a considerable load on the device, especially when this is a large
VPN gateway or an IoT constrained device.</t>
<t> This document concerns itself with the selection of cryptographic algorithms for the use
of IKEv2, specifically with the selection of "mandatory-to-implement" algorithms. The algorithms
identified in this document as "MUST implement" or "SHOULD implement" are not known to be
broken at the current time, and cryptographic research so far leads us to believe that they
will likely remain secure into the foreseeable future. However, this isn't necessarily forever
and it is expected that new revisions of this document will be issued from time to time to
reflect the current best practice in this area.</t>
</section>
<section anchor="iana" title="IANA Considerations">
<t>This document makes no requests of IANA.</t>
</section>
<section anchor="ack" title="Acknowledgements">
<t> The first version of this document was RFC 4307 by Jeffrey I. Schiller of the Massachusetts
Institute of Technology (MIT). Much of the original text has been copied verbatim.</t>
<t> We would like to thank Paul Hoffman, Yaron Sheffer, John Mattsson and Tommy Pauly for their
valuable feedback.</t>
</section>
</middle>
<!-- ====================================================================== -->
<back>
<references title="Normative References">
&rfc2119;
&rfc4106;
&rfc4307;
&rfc7296;
&rfc5282;
</references>
<references title="Informative References">
&rfc7427;
&rfc6989;
<reference anchor="IKEV2-IANA" target="http://www.iana.org/assignments/ikev2-parameters">
<front>
<title>Internet Key Exchange Version 2 (IKEv2) Parameters</title>
<author initials="" surname="" fullname="">
<organization />
</author>
<date />
</front>
</reference>
<reference anchor="TRANSCRIPTION">
<front>
<title>Transcript Collision Attacks: Breaking Authentication in TLS, IKE, and SSH</title>
<author initials="K." surname="Bhargavan" fullname="Karthikeyan Bhargavan">
<organization>INRIA</organization>
</author>
<author initials="G." surname="Leurent" fullname=" Gaetan Leurent">
<organization>INRIA</organization>
</author>
<date month="feb" year="2016" />
</front>
<seriesInfo name="NDSS" value="" />
</reference>
</references>
<!-- ====================================================================== -->
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 07:15:39 |