TestKeyGenerator.kt

package demo

import java.security.SecureRandom
import java.util.*
import javax.crypto.KeyGenerator

fun main(args: Array<String>) {
    val kgs = listOf(KeyGenerator.getInstance("AES").apply { init(SecureRandom()) },
            KeyGenerator.getInstance("AES").apply { init(128) })

    for (kg in kgs) {
        val key = kg.generateKey()
        val content = String(Base64.getUrlEncoder().encode(key.encoded))
        println(content + " " + content.length)
    }

}