1package mox

2

3import (

4 cryptorand "crypto/rand"

5 "encoding/binary"

6 "fmt"

7 mathrand2 "math/rand/v2"

8 "sync"

9)

10

11type rand struct {

12 rand *mathrand2.Rand

13 sync.Mutex

14}

15

16// NewPseudoRand returns a new PRNG seeded with random bytes from crypto/rand. Its

17// functions can be called concurrently.

18func NewPseudoRand() *rand {

19 var seed [32]byte

20 if _, err := cryptorand.Read(seed[:]); err != nil {

21 panic(err)

22 }

23 return &rand{rand: mathrand2.New(mathrand2.NewChaCha8(seed))}

24}

25

26func (r *rand) Float64() float64 {

27 r.Lock()

28 defer r.Unlock()

29 return r.rand.Float64()

30}

31

32func (r *rand) IntN(n int) int {

33 r.Lock()

34 defer r.Unlock()

35 return r.rand.IntN(n)

36}

37

38// CryptoRandInt returns a cryptographically random number.

39func CryptoRandInt() int64 {

40 buf := make([]byte, 8)

41 _, err := cryptorand.Read(buf)

42 if err != nil {

43 panic(fmt.Errorf("reading random bytes: %v", err))

44 }

45 return int64(binary.LittleEndian.Uint64(buf))

46}

47