Use crypto/rand library to generate random numbers

rand.go

package main

import (
    "crypto/rand"
    "fmt"
)

func main() {
    c := 10
    b := make([]byte, c)
    _, err := rand.Read(b)
    if err != nil {
        fmt.Println("error:", err)
        return
    }
    // The slice should now contain random bytes instead of only zeroes.
    fmt.Printf("%#v\n", b)

}