AccessToken

gistfile1.scala

package security

import scala.concurrent._

object AccessToken {

  /**
   * The "b64token" syntax allows the 66 unreserved URI characters
   * ([RFC3986]), plus a few others, so that it can hold a base64,
   * base64url (URL and filename safe alphabet), base32, or base16 (hex)
   * encoding, with or without padding, but excluding whitespace
   * ([RFC4648]).
   *
   * http://tools.ietf.org/html/draft-ietf-httpbis-p7-auth-19#section-2.1
   *
   * Section 2.3. Unreserved Characters
   * http://www.ietf.org/rfc/rfc2396.txt
   *
   * The additional characters to the unreserved characters of rfc2396 are:
   * "+", "/"
   */
  private val Chars = ('a' to 'z') ++ ('A' to 'Z') ++ ('0' to '9') ++ ("-_.!~*'()+/")

  private val Length = 32

  private val random = new scala.util.Random(new java.security.SecureRandom())

  private def uniqueRandomToken(chars: String, length: Int, uniqueFunc: String => Future[Boolean])(implicit ec: ExecutionContext): Future[String] = {
    val newKey = (1 to length).map(x => chars(random.nextInt(chars.length))).mkString
    uniqueFunc(newKey).flatMap(unique => if (unique) Future(newKey) else uniqueRandomToken(chars, length, uniqueFunc)(ec))
  }

  def generate(isUnique: String => Future[Boolean])(implicit ec: ExecutionContext) = uniqueRandomToken(Chars.mkString, Length, isUnique)

}