[tsvwg] Query regarding random parameter in SCTP-AUTH RFC 4895

[Shweta r <[e-mail]>]

Hi Group,

Greetings. I have a doubt regarding SCTP RFC 4895.


1)      section "3.1.  Random Parameter (RANDOM)".


      Random Number: n bytes (unsigned integer)
      This value represents an arbitrary Random Number in network byte order.

     Section 6.1.  Establishment of an Association Shared Key

    An SCTP endpoint willing to receive or send authenticated chunks MUST
    send one RANDOM parameter in its INIT or INIT-ACK chunk.  The RANDOM
    parameter MUST contain a 32-byte Random Number.

----> The random of size 32 bytes should be in network byte order means 32bytes is divided into 4 bytes partition (totally 8 partitions) and then ntohl is done for each partition ?


2)      Peer has asked for HB authentication.

In the scenario of sending HB to unconfirmed address, is it correct to bundle AUTH+HB and send to unconfirmed address ?

My doubt here is can AUTH be sent to unconfirmed address ?



3)      In 4985, it is given,



[cid:[e-mail]0]



Local (auth support)                                                      Peer (Auth not support)



Send INIT with auth para and chunklist(DATA) -->

                                                                        <-----  sends INIT-ACK without auth parameters  (as per above section,  Peer ignore auth parameter received in INIT and sends INIT-ACK)

Cookie echo                                                   --->

                                                                      <----     cookie ack



                                               Association established.

                                                                     <----   sends DATA without AUTH chunk



Local should send SACK or discard the DATA as it does not have AUTH ?



4)      6.1.  Establishment of an Association Shared Key


    The concatenation is performed on byte vectors, and all numerical
   comparisons use network byte order to convert the key vectors to a number.

---->Can you please explain about how to convert key vector to a number and what should be the size of this number.


5)      What should be the length of  Association Shared Key ?  (As per RFC 2104 , the key can be of any length upto 64 bytes)


6)      For client SHA-1 most preferable

For server SHA-256 most preferable





       SCTP Client                                             SCTP Server

INIT send with (SHA-1, SHA-256)  ---->

                                                     <----   INIT Ack ( SHA-256, SHA-1)

Cookie                                         --->

                                                    <---  cookie ack



                                                    <--- sends DATA with  AUTH chunk HMAC Identifier= SHA-1


      Send SACK with AUTH chunk hmac id = SHA-256 ---->

         DATA & SACK processing should be success , this is my understanding.

        What is your opinion?




________________________________

Regards,
Shweta K R
Tester - VPP, 2012 LAB

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