> One of the purposes of reserving this bit is to avoid "bidding down" > attacks in Mobile IPv6 binding update security, whereby an attacker > requests a less secure method so it can mount an attack. One issue that > comes to mind is that, by reducing the size of the address space, a > reserved bit essentially makes it easier for an attacker to randomly > seek through the address space for addresses that aren't protected by > the bit. I've not actually gone through an in-depth analysis of this, so > the statistics may still put such search in the category of a hard > problem, but nevertheless I think it needs some consideration (if it > hasn't already had some).
Sorry, wrong topic. The purpose of *reserving* the bit(s) is to leave the door open to assign the bit(s) to something, hopefully useful, in the future. It is true that a possible *use* of the bits in the future is avoiding bidding down attacks in MIPv6. As part of developping a proposal for that would presumably require the type of analysis that you are pointing out. But, as pointed out in my original email on the subject, any such proposal for *using* the reserved bits for something, would need to go through the normal IETF standards track process. Reserving the bits just requires the analysis whether the cost of carving off the bits is worth the potential benefits of being able to use them for something in the future. Is that more clear? Erik -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
