Cryptographic Policies in Fedora
As part of providing a unified cryptography experience, all packages in Fedora are required to respect the system-wide cryptographic policies. This limits the algorithms permitted for cryptographic operations such as signing, hashing, and key exchange to a common set of algorithms that are considered secure and appropriate for the use case.
More information about publishing a package into Fedora that interacts with the cryptographic policies can be found in the Packaging Guidelines here.
Fedora Crypto Policies
Cryptographic policies and the tools for managing them are provided by the crypto-policies package in Fedora. In the git repository for the package you can find the policy definition files, showing the algorithms that will be supported by the system when they are activated. The policy definitions are maintained by the Fedora Crypto Team, who you should contact with queries and proposed changes.
The currently active policy can be changed using the update-crypto-policies tool, which will apply the policy system-wide by generating configuration files for various applications and libraries to use (such as OpenSSL, Java, and OpenSSH).
The FIPS policy can be used to limit the permitted ciphers to those approved by NIST for use on FIPS 140-3 systems, but does not make the system FIPS compliant on its own. More information on using Fedora in a FIPS compliant way can be found here, however Fedora is not FIPS certified.
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Sub-policies
In addition to the high-level policies, a number of sub-policies are provided to allow users to enable or disable specific algorithms for specific use cases. You can activate a sub-policy by appending it to the policy name, using the process seen below.
$ update-crypto-policies --show
DEFAULT
$ update-crypto-policies --set DEFAULT:AD-SUPPORT
Setting system policy to DEFAULT:AD-SUPPORT
Note: System-wide crypto policies are applied on application start-up.
It is recommended to restart the system for the change of policies
to fully take place.Active Directory
Some Active Directory environments require the use of legacy algorithms such as RC4 and MD5 in Kerberos. The algorithms are not enabled by default in Fedora, but a separate AD-SUPPORT sub-policy can be activated to allow their use.
Post-Quantum
To help facilitate the transition to post-quantum cryptography, Fedora already includes several post-quantum algorithms in the DEFAULT policy. This includes native ML-DSA signatures and hybrid ML-KEM key exchange mechanisms.
If you’d like to test other post-quantum algorithms, a separate TEST-PQ sub-policy is available which includes a wider range of algorithms, including some which are not yet fully standardised. This adds SPHINCS+ and FALCON algorithms to the existing permitted algorithms.
Some of the policies included in the TEST-PQ policy have not yet completed the formal review process, and could be subject to change. The policies have not received NIST certification and may be cryptographically flawed.
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