common/src/main/scala/com/heluna/maildrop/util/AltInbox.scala

gistfile1.txt

package com.heluna.maildrop.util
 
/**
 * common com.heluna.maildrop
 * User: markbe
 * Date: 9/10/14
 * Time: 9:39 AM
 */
 
object AltInbox {
 
  val modifier = BigInt(MailDropConfig.getLong("maildrop.data.alt-inbox-modifier").getOrElse(0L).toString)
  val prefix = MailDropConfig("maildrop.data.alt-inbox-prefix").getOrElse("D-")
 
  def fromShort(shortId: String) = BigInt(shortId, 36) 
 
  // Simple algorithm to determine alt inbox.
  // Warning -- this won't stop any dedicated attackers at all.
  // - Strip non alpha-numeric characters
  // - Convert the regular inbox to a long
  // - Reverse the digits and prepend a 1 
  // - Add the private modifier
  // - Convert back to base36
  // - Prepend prefix
 
  def getAltInbox(regularInbox: String): String = { 
    //val regularBigInt = fromShort(regularInbox.toLowerCase.replaceAll("[^A-Za-z0-9]", ""))
    val regularBigInt = fromShort(regularInbox)
    prefix + (BigInt("1" + regularBigInt.toString().reverse) + modifier).toString(36)
  }
 
  // Simple algorithm to determine regular inbox.
  // - Strip prefix
  // - Convert the alt inbox to a long
  // - Subtract the private modifier
  // - Remove the 1 prefix and reverse the digits
  // - Convert back to base36
 
  def getRegularInbox(altInbox: String): String = { 
    //val altBigInt = fromShort(altInbox.toLowerCase.replaceFirst(prefix.toLowerCase, ""))
    val altBigInt = fromShort(altInbox.replaceFirst(prefix, ""))
    BigInt((altBigInt - modifier).toString().substring(1).reverse).toString(36)
  }
 
}