NixOS must employ approved cryptographic hashing algorithms for all stored passwords.

Unapproved mechanisms that are used for authentication to the cryptographic module are not verified and therefore cannot be relied upon to provide confidentiality or integrity, and DOD data may be compromised. Operating systems using encryption are required to use FIPS-compliant mechanisms for authenticating to cryptographic modules. FIPS 140-3 is the current standard for validating that mechanisms used to access cryptographic modules use authentication that meets DOD requirements. This allows for Security Levels 1, 2, 3, or 4 for use on a general purpose computing system.