单值上下文中的多值“crypto/rand”.Int()

Question

I am trying to generate a random number using the library crypto/rand. The earlier implementation of this function used math/rand, but I need to use crypto/rand. This is my function below

func GenerateNum() (num string) {
num = fmt.Sprintf("02:fc:%02x:%02x:%02x:%02x", rand.Int(rand.Reader, big.NewInt(256)),
rand.Int(rand.Reader, big.NewInt(256)), rand.Int(rand.Reader, big.NewInt(256)),
rand.Int(rand.Reader, big.NewInt(256))
)
return
}

I am fairly new to this language and hence not able to figure out what should be done.

Answer 1

You can do something like this (although this might not be the best approach)

package main

import (
    "crypto/rand"
    "fmt"
    "log"
    "math/big"
)

func cryptoRandSecure() *big.Int {
    nBig, err := rand.Int(rand.Reader, big.NewInt(256))
    if err != nil {
        log.Println(err)
    }
    return nBig
}

func GenerateNum() (num string) {
    n1 := cryptoRandSecure()
    n2 := cryptoRandSecure()
    n3 := cryptoRandSecure()
    n4 := cryptoRandSecure()
    num = fmt.Sprintf("02:fc:%02x:%02x:%02x:%02x", n1, n2, n3, n4)
    return
}

func main() {
    num := GenerateNum()
    fmt.Println(num)
}