package com.peachpasswords.sync

object SASDerivation {
    fun derive(handshakeHash: ByteArray): String {
        require(handshakeHash.size >= 4) { "Handshake hash too short" }
        val n = (((handshakeHash[0].toInt() and 0xFF) shl 24) or
                ((handshakeHash[1].toInt() and 0xFF) shl 16) or
                ((handshakeHash[2].toInt() and 0xFF) shl 8) or
                (handshakeHash[3].toInt() and 0xFF)).toLong() and 0xFFFFFFFFL
        return (n % 1_000_000L).toString().padStart(6, '0')
    }
}