[strongSwan] non-zero reserved fields in IKE_AUTH response.

[Richard Knight]

Martin, Thanks for the reply.

I actually  did not make any changes to the IKE_SA_INIT packet,  I only
changed the reserved fields in the IKE_AUTH message.


Jamie Knight (rjknight at us.ibm.com)
IBM Power Firmware Development
(512) 286-7017 (t/l 386-7017)
office 045/2A-01
IBM Austin, TX


                                                                                                                                       
  From:       Martin Willi <martin at strongswan.org>                                                                                     
                                                                                                                                       
  To:         Richard Knight/Austin/IBM at IBMUS                                                                                          
                                                                                                                                       
  Cc:         users at lists.strongswan.org                                                                                               
                                                                                                                                       
  Date:       06/29/2010 02:53 AM                                                                                                      
                                                                                                                                       
  Subject:    Re: [strongSwan] non-zero reserved fields in IKE_AUTH response.                                                          
                                                                                                                                       





Hi Richard,

> Could someone point me to where the calculation would start and end in
the
> message below?

Start with the IKE_SA SPIs of the IKE_SA_INIT (_not_ the IKE_AUTH seen
here!):

> | | | IKE_SA Initiator's SPI         = c3dfaad709d6bd4b
> | | | IKE_SA Responder's SPI         = fd546d59933dbe69
> | | | Next Payload                   = 46 (E)
> | | | Major Version                  = 2
> | | | Minor Version                  = 0
> | | | Exchange Type                  = 35 (IKE_AUTH)
> | | | Flags                          = 73 (0b01001001)
> | | | | Reserved  (XX000000)             = 64
> | | | | Response  (00R00000)             = 0
> | | | | Version   (000V0000)             = 0
> | | | | Initiator (0000I000)             = 1
> | | | | Reserved  (00000XXX)             = 1

And include all further bytes of the message. Append the nonce of the
other IKE_SA_INIT packet, and prf(Sk_px, IDx').

> 09[IKE] authentication of '2001:db8:1:1::1234' (myself) with pre-shared
key
> 09[IKE] octets = message + nonce + prf(Sk_px, IDx') => 342 bytes @
0x100636b0
> 09[IKE]    0: CF B9 0A AB 05 DB A9 95 C7 FE 12 99 E1 E9 AD
B7  ................
> 09[IKE]   16: 21 20 22 20

0x22 is IKE_SA_INIT, starting with a SECURITY_ASSOCIATION payload
(0x21).
Flags is 0x20, meaning the responder flag is set only. Did you set other
reserved flags in the IKE_SA_INIT message?

Regards
Martin