Reputation: 6662
I want to generate 64-bit random integer using the secure crypto/rand
package. I found this online:
package main
import (
"crypto/rand"
"encoding/base64"
)
// GenerateRandomBytes returns securely generated random bytes.
// It will return an error if the system's secure random
// number generator fails to function correctly, in which
// case the caller should not continue.
func GenerateRandomBytes(n int) ([]byte, error) {
b := make([]byte, n)
_, err := rand.Read(b)
// Note that err == nil only if we read len(b) bytes.
if err != nil {
return nil, err
}
return b, nil
}
But it seems to generate random bytes instead. I want a random 64-bit int. Namely, I want something like var i uint64 = rand()
. Any ideas how to achieve this?
Upvotes: 3
Views: 4535
Reputation: 5375
You also use rand.Int
in crypto/rand
package
func randint64() (int64, error) {
val, err := rand.Int(rand.Reader, big.NewInt(int64(math.MaxInt64)))
if err != nil {
return 0, err
}
return val.Int64(), nil
}
https://play.golang.org/p/fqoQxpmjOSu
Upvotes: 2
Reputation:
You can generate a random number with crypto.Rand
, and then convert those bytes to an int64 using the binary
package:
func randint64() (int64, error) {
var b [8]byte
if _, err := rand.Read(b[:]); err != nil {
return 0, err
}
return int64(binary.LittleEndian.Uint64(b[:])), nil
}
https://play.golang.org/p/2Q8tvttqbJ (result is cached)
If you look at the source code for LittleEndian.Uint64
, you can see it's simply performing a few bit operations on the data; something that you could implemented for yourself.
Upvotes: 3