Audit the random number generation source (rand) GSC-G404
Use of weak random number generator (math/rand instead of crypto/rand)
21func RandomImageWithSize(size int, data []byte) (image.Image, error) {
22 randExtent := len(palette.WebSafe) - 32
23 rand.Seed(time.Now().UnixNano())
24 colorIndex := rand.Intn(randExtent)25 backColorIndex := colorIndex - 1
26 if backColorIndex < 0 {
27 backColorIndex = randExtent - 1
Description
math/rand is much faster for applications that don’t need crypto-level or security-related random data generation. crypto/rand is suited for secure and crypto-ready usage, but it’s slower. But in most cases, crypto/rand is likely to be more suitable, unless the performance is critical but the application's security is not (which is rare).
It is highly recommended to use crypto/rand when needing to be secure with random numbers such as generating session ID in a web application.
- crypto/rand package
- math/rand package
Bad practice
package main
import "math/rand"
func main() {
bad := rand.Int()
println(bad)
}
Recommended
package main
import "crypto/rand"
func main() {
good, _ := rand.Read(nil)
println(good)
}