Secure Random String

README.md

Class usage

Just paste it to a project that supports kotlin language and write a package declaration on the top. Done.

Run from console

Requires kscript to run as a script:

sdk install kscript

Run:

kscript RandomStringScript.kts

Java UUID's are not secure enough. This class and script do a better job at generating secure random Strings.

Thanks!

Thanks for allow importing files in kotlin scripts: https://github.com/holgerbrandl/kscript

Thanks to this Java RandomString implementation that served as a solid base to build on: https://stackoverflow.com/questions/41107/how-to-generate-a-random-alpha-numeric-string/41156#41156

RandomString.kt

import java.util.*
import java.security.SecureRandom

class RandomString(
    length: Int = 21,
    val random: Random = SecureRandom(),
    symbolsString: String = RandomString.alphanum
) {
    val buf: CharArray
    val symbols: CharArray

    init {
        buf = CharArray(length)
        symbols = symbolsString.toSet().toCharArray()
        if (length < 1 || symbolsString.length < 2) 
            throw IllegalArgumentException()
    }

    fun nextString(): String {
        for (idx in 0 until buf.size)
            buf[idx] = symbols[random.nextInt(symbols.size)]
        return String(buf)
    }

    companion object RandomStringStatic {
        val upper: String = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
        val lower: String = upper.toLowerCase(Locale.ROOT)
        val digits: String = "0123456789"
        val alphanum: String = upper + lower + digits
    }
}

RandomStringScript.kts

//INCLUDE RandomString.kt

System.out.println(RandomString().nextString())