[role="xpack"]
[[fips-140-compliance]]
=== FIPS 140-2

The Federal Information Processing Standard (FIPS) Publication 140-2, (FIPS PUB
140-2), titled "Security Requirements for Cryptographic Modules" is a U.S.
government computer security standard used to approve cryptographic modules.
{es} offers a FIPS 140-2 compliant mode and as such can run in a FIPS 140-2
enabled JVM. In order to set {es} in fips mode, you must set the
`xpack.security.fips_mode.enabled` to `true` in `elasticsearch.yml`

For {es}, adherence to FIPS 140-2 is ensured by

- Using FIPS approved / NIST recommended cryptographic algorithms.
- Delegating the implementation of these cryptographic algorithms to a NIST
  validated cryptographic module (available via the Java Security Provider
  in use in the JVM).
- Allowing the configuration of {es} in a FIPS 140-2 compliant manner, as
  documented below.

[float]
=== Upgrade considerations

If you plan to upgrade your existing Cluster to a version that can be run in
a FIPS 140-2 enabled JVM, the suggested approach is to first perform a rolling
upgrade to the new version in your existing JVM and perform all necessary
configuration changes in preparation for running in fips mode. You can then
perform a rolling restart of the nodes, this time starting each node in the FIPS
140-2 JVM. This will allow {es} to take care of a couple of things automatically for you:

- <<secure-settings, Secure Settings>> will be upgraded to the latest format version as
  previous format versions cannot be loaded in a FIPS 140-2 JVM.
- Self-generated trial licenses will be upgraded to the latest format that
  is compliant with FIPS 140-2.

If you are on a appropriate license level (platinum) you can elect to perform
a rolling upgrade while at the same time running each upgraded node in a
FIPS 140-2 JVM. In this case, you would need to also regenerate your
`elasticsearch.keystore` and migrate all secure settings to it, in addition to the
necessary configuration changes outlined below, before starting each node.

[float]
=== Configuring {es} for FIPS 140-2

Apart from setting `xpack.security.fips_mode.enabled`, a number of security
related settings need to be configured accordingly in order to be compliant
and able to run {es} successfully in a FIPS 140-2 enabled JVM.

[float]
==== TLS

SSLv2 and SSLv3 are not allowed by FIPS 140-2, so `SSLv2Hello` and `SSLv3` cannot
be used for <<ssl-tls-settings, xpack.ssl.supported_protocols>>

NOTE: The use of TLS ciphers is mainly governed by the relevant crypto module
(the FIPS Approved Security Provider that your JVM uses). All the ciphers that
are configured by default in {es} are FIPS 140-2 compliant and as such can be
used in a FIPS 140-2 JVM. (see <<ssl-tls-settings, xpack.ssl.cipher_suites>>)

[float]
==== TLS Keystores and keys

Keystores can be used in a number of <<ssl-tls-settings>> in order to
conveniently store key and trust material. Neither `JKS`, nor `PKCS#12` keystores
can be used in a FIPS 140-2 enabled JVM however, so you must refrain from using
these keystores.  Your FIPS 140-2 provider may provide a compliant keystore that
can be used or you can use PEM encoded files. To use PEM encoded key material,
you can use the relevant `\*.key` and `*.certificate` configuration
options, and for trust material you can use `*.certificate_authorities`.


FIPS 140-2 compliance dictates that the length of the public keys used for TLS
must correspond to the strength of the symmetric key algorithm in use in TLS.
Depending on the value of <<ssl-tls-settings, xpack.ssl.cipher_suites>> that
you select to use, the TLS keys must have corresponding length according to
the following table:

[[comparable-key-strength]]
.Comparable key strengths
|=======================
| Symmetric Key Algorithm | RSA key Length | ECC key length
| `3DES`                  | 2048           | 224-255
| `AES-128`               | 3072           | 256-383
| `AES-256`               | 15630          | 512+
|=======================

[float]
==== Password Hashing

{es} offers a number of algorithms for securely hashing credentials in memory and
on disk. However, only the `PBKDF2` family of algorithms is compliant with FIPS
140-2 for password hashing. You must set the the `cache.hash_algo` realm settings
and the `xpack.security.authc.password_hashing.algorithm` setting to one of the
available `PBKDF2` values.
See <<hashing-settings>>.

Password hashing configuration changes are not retroactive so the stored hashed
credentials of existing users of the file and native realms will not be updated
on disk.
Authentication will still work, but in order to ensure FIPS 140-2 compliance,
you would need to recreate users or change their password using the
<<users-command, elasticsearch-user>> CLI tool for the file realm and the
<<security-api-users,User Management APIs>> for the native realm.

The user cache will be emptied upon node restart, so any existing hashes using
non-compliant algorithms will be discarded and the new ones will be created
using the compliant `PBKDF2` algorithm you have selected.

[float]
=== Limitations

Due to the limitations that FIPS 140-2 compliance enforces, a small number of
features are not available while running in fips mode. The list is as follows:

* Azure Classic Discovery Plugin
* Ingest Attachment Plugin
* The {ref}/certutil.html[`elasticsearch-certutil`] tool. However,
 `elasticsearch-certutil` can very well be used in a non FIPS 140-2
  enabled JVM (pointing `JAVA_HOME` environment variable to a different java
  installation) in order to generate the keys and certificates that
  can be later used in the FIPS 140-2 enabled JVM.
* The `elasticsearch-plugin` tool. Accordingly, `elasticsearch-plugin` can be
  used with a different (non FIPS 140-2 enabled) Java installation if
  available.
* The SQL CLI client cannot run in a FIPS 140-2 enabled JVM while using
  TLS for transport security or PKI for client authentication.
* The SAML Realm cannot decrypt and consume encrypted Assertions or encrypted
  attributes in Attribute Statements from the SAML IdP.
