random.go

package utils

import (
	crand "crypto/rand"
	"math/big"
	"math/rand"
	"time"
)

func init() {
	rand.Seed(time.Now().UnixNano())
}

var letterRunes = []rune("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")

// RandomStringWithLength generate random string with specific length
func RandomStringWithLength(n int) string {
	b := make([]rune, n)
	for i := range b {
		b[i] = letterRunes[rand.Intn(len(letterRunes))]
	}
	return string(b)
}

// SecRandomStringWithLength generate random string with specific length
func SecRandomStringWithLength(n int) (string, error) {
	b := make([]rune, n)
	for i := range b {
		idx, err := SecRandInt(len(letterRunes))
		if err != nil {
			return "", err
		}

		b[i] = letterRunes[idx]
	}

	return string(b), nil
}

// SecRandInt generate security int
func SecRandInt(n int) (int, error) {
	bn, err := crand.Int(crand.Reader, big.NewInt(int64(n)))
	if err != nil {
		return 0, err
	}

	return int(bn.Int64()), nil
}