1package mox

2

3import (

4 cryptorand "crypto/rand"

5 "encoding/binary"

6 "fmt"

7 mathrand "math/rand"

8 "sync"

9)

10

11type rand struct {

12 *mathrand.Rand

13 sync.Mutex

14}

15

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

17func NewPseudoRand() *rand {

18 return &rand{Rand: mathrand.New(mathrand.NewSource(CryptoRandInt()))}

19}

20

21// Read can be called concurrently.

22func (r *rand) Read(buf []byte) (int, error) {

23 r.Lock()

24 defer r.Unlock()

25 return r.Rand.Read(buf)

26}

27

28// CryptoRandInt returns a cryptographically random number.

29func CryptoRandInt() int64 {

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

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

32 if err != nil {

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

34 }

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

36}

37