rand

Overview ¶

Package rand defines methods of obtaining random number generators.

One is expected to use randomness from this package only, without introducing any other packages. This limits the scope of code that needs to be hardened.

There are two modes, one for deterministic and another non-deterministic randomness: 1. If deterministic pseudo-random generator is enough, use:

	import "github.com/prysmaticlabs/prysm/v4/crypto/rand"
	randGen := rand.NewDeterministicGenerator()
	randGen.Intn(32) // or any other func defined in math.rand API

   In this mode, only seed is generated using cryptographically secure source (crypto/rand). So,
   once seed is obtained, and generator is seeded, the next generations are deterministic, thus fast.
   However given that we only seed this 63 bits from crypto/rand and use math/rand to generate the outputs,
   this method is not cryptographically secure. This is directly stated in the math/rand package,
   https://github.com/golang/go/blob/release-branch.go1.17/src/math/rand/rand.go#L15. For any security
   sensitive work this particular generator is NOT to be used.

2. For cryptographically secure non-deterministic mode (CSPRNG), use:

	import "github.com/prysmaticlabs/prysm/v4/crypto/rand"
	randGen := rand.NewGenerator()
	randGen.Intn(32) // or any other func defined in math.rand API

   Again, any of the functions from `math/rand` can be used, however, they all use custom source
   of randomness (crypto/rand), on every step. This makes randomness non-deterministic. However,
   you take a performance hit -- as it is an order of magnitude slower.