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. Elasticsearch offers a FIPS 140-2 compliant mode and as such can run in a FIPS 140-2 configured JVM.

After configuring your JVM for FIPS 140-2, you can run Elasticsearch in FIPS 140-2 mode by setting the xpack.security.fips_mode.enabled to true in elasticsearch.yml.

For Elasticsearch, adherence to FIPS 140-2 is ensured by:

If you plan to upgrade your existing cluster to a version that can be run in a FIPS 140-2 configured JVM, we recommend 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 140-2 mode. You can then perform a rolling restart of the nodes, starting each node in a FIPS 140-2 JVM. During the restart, Elasticsearch:

If your subscription already supports FIPS 140-2 mode, 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 manually regenerate your elasticsearch.keystore and migrate all secure settings to it, in addition to the necessary configuration changes outlined below, before starting each node.

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 Elasticsearch successfully in a FIPS 140-2 configured JVM.

FIPS 140-2 (via NIST Special Publication 800-132) dictates that encryption keys should at least have an effective strength of 112 bits. As such, the Elasticsearch keystore that stores the node’s secure settings needs to be password protected with a password that satisfies this requirement. This means that the password needs to be 14 bytes long which is equivalent to a 14 character ASCII encoded password, or a 7 character UTF-8 encoded password. You can use the elasticsearch-keystore passwd subcommand to change or set the password of an existing keystore. Note that when the keystore is password-protected, you must supply the password each time Elasticsearch starts.

SSLv2 and SSLv3 are not allowed by FIPS 140-2, so SSLv2Hello and SSLv3 cannot be used for ssl.supported_protocols.

Keystores can be used in a number of General 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 configured JVM. Avoid using these types of keystores. Your FIPS 140-2 provider may provide a compliant keystore implementation 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.cipher_suites that you select to use, the TLS keys must have corresponding length according to the following table:

While Elasticsearch offers a number of algorithms for securely hashing credentials on disk, only the PBKDF2 based family of algorithms is compliant with FIPS 140-2 for stored password hashing. However, since PBKDF2 is essentially a key derivation function, your JVM security provider may enforce a 112-bit key strength requirement. Although FIPS 140-2 does not mandate user password standards, this requirement may affect password hashing in Elasticsearch. To comply with this requirement, while allowing you to use passwords that satisfy your security policy, Elasticsearch offers pbkdf2_stretch which is the suggested hashing algorithm when running Elasticsearch in FIPS 140-2 environments. pbkdf2_stretch performs a single round of SHA-512 on the user password before passing it to the PBKDF2 implementation.

You must set the xpack.security.authc.password_hashing.algorithm setting to one of the available pbkdf_stretch_* values. When FIPS-140 mode is enabled, the default value for xpack.security.authc.password_hashing.algorithm is pbkdf2_stretch. See User cache and password hash algorithms.

Password hashing configuration changes are not retroactive so the stored hashed credentials of existing users of the reserved, native, and file realms are not updated on disk. To ensure FIPS 140-2 compliance, recreate users or change their password using the elasticsearch-user CLI tool for the file realm and the create users and change password APIs for the native and reserved realms. Other types of realms are not affected and do not require any changes.

ssha256 (salted sha256) is recommended for cache hashing. Though PBKDF2 is compliant with FIPS-140-2, it is — by design — slow, and thus not generally suitable as a cache hashing algorithm. Cached credentials are never stored on disk, and salted sha256 provides an adequate level of security for in-memory credential hashing, without imposing prohibitive performance overhead. You may use PBKDF2, however you should carefully assess performance impact first. Depending on your deployment, the overhead of PBKDF2 could undo most of the performance gain of using a cache.

Either set all cache.hash_algo settings to ssha256 or leave them undefined, since ssha256 is the default value for all cache.hash_algo settings. See User cache and password hash algorithms.

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 algorithm you have selected.

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