66 lines
1.5 KiB
Go
66 lines
1.5 KiB
Go
|
package seed
|
||
|
|
|
||
|
|
import (
|
||
|
|
crand "crypto/rand"
|
||
|
|
"fmt"
|
||
|
|
"math"
|
||
|
|
"math/big"
|
||
|
|
"math/rand"
|
||
|
|
"sync"
|
||
|
|
"time"
|
||
|
|
)
|
||
|
|
|
||
|
|
var (
|
||
|
|
once sync.Once
|
||
|
|
secure bool
|
||
|
|
seeded bool
|
||
|
|
)
|
||
|
|
|
||
|
|
// Init provides best-effort seeding (which is better than running with Go's
|
||
|
|
// default seed of 1). If `/dev/urandom` is available, Init() will seed Go's
|
||
|
|
// runtime with entropy from `/dev/urandom` and return true because the runtime
|
||
|
|
// was securely seeded. If Init() has already initialized the random number or
|
||
|
|
// it had failed to securely initialize the random number generation, Init()
|
||
|
|
// will return false. See MustInit().
|
||
|
|
func Init() (bool, error) {
|
||
|
|
var err error
|
||
|
|
once.Do(func() {
|
||
|
|
var n *big.Int
|
||
|
|
n, err = crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
|
||
|
|
if err != nil {
|
||
|
|
rand.Seed(time.Now().UTC().UnixNano())
|
||
|
|
return
|
||
|
|
}
|
||
|
|
rand.Seed(n.Int64())
|
||
|
|
secure = true
|
||
|
|
seeded = true
|
||
|
|
})
|
||
|
|
return seeded && secure, err
|
||
|
|
}
|
||
|
|
|
||
|
|
// MustInit provides guaranteed seeding. If `/dev/urandom` is not available,
|
||
|
|
// MustInit will panic() with an error indicating why reading from
|
||
|
|
// `/dev/urandom` failed. See Init()
|
||
|
|
func MustInit() {
|
||
|
|
once.Do(func() {
|
||
|
|
n, err := crand.Int(crand.Reader, big.NewInt(math.MaxInt64))
|
||
|
|
if err != nil {
|
||
|
|
panic(fmt.Sprintf("Unable to seed the random number generator: %v", err))
|
||
|
|
}
|
||
|
|
rand.Seed(n.Int64())
|
||
|
|
secure = true
|
||
|
|
seeded = true
|
||
|
|
})
|
||
|
|
}
|
||
|
|
|
||
|
|
// Secure returns true if a cryptographically secure seed was used to
|
||
|
|
// initialize rand.
|
||
|
|
func Secure() bool {
|
||
|
|
return secure
|
||
|
|
}
|
||
|
|
|
||
|
|
// Seeded returns true if Init has seeded the random number generator.
|
||
|
|
func Seeded() bool {
|
||
|
|
return seeded
|
||
|
|
}
|