Feature gate:#![feature(random)]

This is a tracking issue for secure random data generation support instd.

Central to this feature is theRandomSource trait insidecore::random, which generates random bytes.std also exposes the platform's secure random number generator via theDefaultRandomSource type. There is aDistribution<T> trait for distributions that cansample random values of a specific type, and arandom function for convenience to allow things likerandom(1..=6).

Public API

// core::randompubtraitRandomSource{fnfill_bytes(&mutself,bytes:&mut[u8]);}pubtraitDistribution<T>{fnsample(&self,source:&mut(implRandomSource + ?Sized)) ->T;}implDistribution<bool>forRangeFull{ ...}implDistribution</* all integer types */>for/* all range types */{ ...}// std::random (additionally)pubstructDefaultRandomSource;implRandomSourceforDefaultRandomSource{ ...}pubfnrandom<T>(dist:&(implDistribution<T> + ?Sized)) ->T;

Steps / History

• ACP:Simple secure random number generation libs-team#393
• Implementation
  • std: implement therandom feature (alternative version) #129201
  • API rework forDistribution<T> and newrandom
• Final comment period (FCP)¹
• Stabilization PR

Unresolved Questions

• Naming: the ACP usedgen_bytes andDefaultRng, the implementation PR usesfill_bytes andDefaultRandomSource (see argumentsprogen_bytes andprofill_bytes)
• Concerns listed atSimple secure random number generation libs-team#393 (comment) should be addressed