908D C60A

Byte

0x90

Concatenate that with the UTF-8 representation of the password (in this case

test12

):

908D C60A 7465 7374 3132

import kotlin.random.Random
import kotlin.text.Charsets.UTF_8

fun a(pass: String, seed: Long): String {
    val random = Random(seed)
    val salt: ByteArray = random.nextBytes(4)

    val passBytes = pass.toByteArray(charset = UTF_8)
    val toHash = salt + passBytes
    val hashed = sha256(toHash)
    return toBase64(salt + hashed)
}

fun sha256(toHash: ByteArray): ByteArray {
    TODO("not implemented")
}

fun toBase64(bytes: ByteArray): String {
    TODO("not implemented")
}