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Versions: (draft-eastlake-trill-group-keying) 00 01

INTERNET-DRAFT                                           Donald Eastlake
Intended status: Proposed Standard                         Dacheng Zhang
                                                                  Huawei
Expires: July 27, 2018                                  January 28, 2018

                  Simple Group Keying Protocol (SGKP)
                 <draft-ietf-trill-group-keying-01.txt>


Abstract

   This document specifies a simple general group keying protocol that
   provides for the distribution of shared secret keys to group members
   and the management of such keys. It assumes that secure pairwise keys
   can be created between any two group members.


Status of This Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Distribution of this document is unlimited. Comments should be sent
   to the authors or the TRILL working group mailing list:
   trill@ietf.org.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html. The list of Internet-Draft
   Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.















D. Eastlake                                                     [Page 1]


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Table of Contents

      1. Introduction............................................3
      1.1  Terminology and Acronyms..............................3

      2. Simple Group Keying Protocol............................4
      2.1 Assumptions............................................4
      2.2 Group Keying Procedure Overview........................4
      2.3 Transmission and Receipt of Group Data Messages........5
      2.4 Changes in Group Membership or GKd.....................6

      3. Group Keying Messages...................................7
      3.1 Set Key Message........................................9
      3.2 Use, Delete, Disuse, or Deleted Key Messages..........11
      3.3 Response Message......................................12
      3.3.1 Response Codes......................................13
      3.4 No-Op Message.........................................15

      4. Security Considerations................................16
      5. IANA Considerations....................................17

      Normative References......................................19
      Informative References....................................19

      Acknowledgements..........................................20
      Authors' Addresses........................................21


























D. Eastlake                                                     [Page 2]


INTERNET-DRAFT                                       Simple Group Keying


1. Introduction

   This document specifies a simple general group keying protocol that
   provides for the distribution of shared secret keys to group members
   and the management of such keys. It assumes that secure pairwise keys
   can be created between any two group members.

   A companion document specifies two profiles for the use of this group
   keying protocol in a case using DTLS and a case using IPsec payload
   formats. It is anticipated that there will be other uses for this
   group keying protocol.



1.1  Terminology and Acronyms

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119] [RFC8174]
   when, and only when, they appear in all capitals, as shown here.

   This document uses the following terminology and acronyms:

      AES - Advanced Encryption Standard.

      DTLS - Datagram Transport Level Security [RFC6347].

      GKd - A distinguished station in a group that is in charge of
         which group keying (Section 2) is in use.

      GKs - Stations in a group other than GKd (Section 2).

      IS-IS - Intermediate System to Intermediate System [RFC7176].

      keying material - The set of a Key ID, a secret key, and a cypher
         suite.

      QoS - Quality of Service.

      RBridge - An alternative term for a TRILL switch.

      TRILL - Transparent Interconnection of Lots of Links or Tunneled
         Routing in the Link Layer.

      TRILL switch - A device that implements the TRILL protocol
         [RFC6325] [RFC7780], sometimes referred to as an RBridge.






D. Eastlake                                                     [Page 3]


INTERNET-DRAFT                                       Simple Group Keying


2. Simple Group Keying Protocol

   This section gives an overview of the assumptions and capabilities of
   the Simple Group Keying Protocol (SGKP) that provides shared secret
   group keys. Further details of the messages used for this protocol
   are give in Section 3.

   Any particular use of this protocol will require profiling giving
   further details and specifics for that use. For example, the envelope
   used for addressing and transmitting the messages of this protocol
   must be specified for any particular use. This protocol is not
   suitable for discovery messages but is intended for use between
   members of a group that have already established or establishable
   pair-wise security.



2.1 Assumptions

   The following are assumed:
      - All pairs of stations in the group can engage in pairwise
        communication with unicast messages and each can groupcast a
        message to the other group members.
      - At any particular time, there is a distinguished station GKd in
        the group that is in charge of keying for the groupcast data
        messages to be sent to the group. The group wide shared secret
        keys established by GKd are referred to herein as "dynamic"
        keys.
      - Pairwise keying has been negotiated between GKd and each other
        station GKs1, GKs2, ... GKsN in the group. These keys are
        referred to in this protocol as "pairwise" keys.
      - There are one or more keys, other than the dynamic or pairwise
        keys, which are already in place at all group member stations
        and may be present at other stations. These are referred to as
        "stable" keys.

   When keying material is stored by a station, it is accompanied by a
   "use flag" indicating whether or not that keying material is usable
   for groupcast transmissions.



2.2 Group Keying Procedure Overview

   GKd sends unicast keying messages to the other stations in the group
   and they respond as specified below and in further detail in the
   particular use profiles of SGKP. All such keying messages MUST be
   encrypted and authenticated using the pairwise keys as further
   specified in the use profile.



D. Eastlake                                                     [Page 4]


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   Typically, GKd sends a keying message to each GKs with keying
   material.  After successful acknowledgement of receipt from each GKs,
   GKd sends a keying message to each GKs instructing it to use the
   dynamic key GKd has set. It would be common for GKd to set a new
   dynamic key at each GKs while an older dynamic key is in use so that
   GKd can more promptly roll over to the new dynamic key when
   appropriate.

   To avoid an indefinite build up of keying material at a GKs, keys
   have a lifetime specified by GKd and GKd can send a message deleting
   a key. (GKd can also send a message indicating that a key is no
   longer to be used but leaving it set.) Should the space available at
   a GKs for keying material be exhausted, on receipt of a Set Key
   keying message from GKd for a new key ID, GKs discards a dynamic key
   it has and originates a Delete Key message to the source of that
   dynamic key.



2.3 Transmission and Receipt of Group Data Messages

   If A group has only one member, transmission of data between group
   members is a moot question and any messages that would be so
   transmitted if the group had more members are discarded.

   If a group has only two members, then pairwise security is used
   between them.

   When a group has more than two members and a station in the group
   transmits a data message to the group, if the transmitter has one or
   more keys set by GKd that it has been instructed to use, it uses one
   of those keys and its associated cypher suite to groupcast the data
   message.  If it has no such key, then it uses serial unicast to send
   the data message to each other member of the group, negotiating
   pairwise keys with them if it does not already have such pairwise
   keys. Thus it is a responsibility of GKd not to authorize the use of
   a groupcast key until it knows that all the GKs have that key.

   When a station in the group receives data that has been groupcast to
   the group, if the receiver has the key referenced by the data message
   the receiver decrypts and verifies it. If verification fails or if
   the receiver does not have the required key, the receiver discards
   the data message. Thus whether GKs has been directed to "use" a key
   by GKd is relevant only to transmission, not reception.








D. Eastlake                                                     [Page 5]


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2.4 Changes in Group Membership or GKd

   When a new station joins the group, GKd SHOULD send that station the
   currently in-use group key and instruct it to use that key and MAY
   send it other keys known to the group members and intended for future
   use.

   If GKd detects that one or more stations that were members of the
   group are no longer members of the group, it SHOULD generate and
   distribute a new group key to the remaining group members, instruct
   them to use this new key, and delete from them any old keys known to
   the departed group member station(s) or at least instructing them to
   dis-use such old keys that are marked for use; however, in the case
   of groups with large and/or highly dynamic membership, where a
   station might frequently leave and then rejoin, it may, as a
   practical matter, be necessary to rekey less frequently.

   A new group member can become GKd due to the previous GKd leaving the
   group or a configuration change or the like. A GKs MUST NOT use
   keying material for transmission that was set by a station that it
   determines is not GKd. To avoid a gap in service, a station that is
   not GKd MAY set keying material at other stations in the group;
   however, such a non-GKd station cannot set the use flag for any such
   keying material.  It is RECOMENDED that the second highest priority
   station to be GKd set such keying material at all other stations in
   the group.  Should a station run out of room for keying material, it
   SHOULD discard keying material set by a station with lower priority
   to be GKd before discarding keying material set by a higher priority
   station and among keys set by GKd is SHOULD discard the lest recently
   used first.






















D. Eastlake                                                     [Page 6]


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3. Group Keying Messages

   Keying messages start with a Version number. This document specifies
   Version zero.

   Keying messages are structured, as shown in Figure 3.1 below, as
      o  a Version number,
      o  a Response flag,
      o  a Key ID length,
      o  the Key ID of a stable key,
      o  a group keying use profile identifier,
      o  possible padding,
      o  a key wrap algorithm specifier, and finally
      o  a key wrapped vector of additional fields wrapped using a key
         derived from the stable key identified.

   Keying messages are always sent unicast and encrypted and
   authenticated with the appropriate pairwise key, all as further
   specified for the particular use profile. It will typically be
   possible for GKd to calculate the keying message once, including the
   wrapping under a key derived from the stable key, then send that
   message to various GKs using the different pairwise keys for each
   GKs.

      +-+-+-+-+-+-+-+-+
      |Ver|R|KeyID1Lng|                  1 byte
      +-+-+-+-+-+-+-+-+...
      | KeyID1  ...                      KeyID1Lngth bytes
      +-+-+-+-+-+-+-+-+...
      | Use Type      |                  1 byte
      +-+-+-+-+-+-+-+-+
      | Pad1 Length   |                  1 byte
      +-+-+-+-+-+-+-+-+...
      | Padding                          Pad1 Length bytes
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...
      | KW Al | KW Length             |   2 bytes
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+...
      |
      | Key Wrapped Material             Variable size
      |
      +-+-+-+-+-+-+-+-...

                     Figure 3.1. Keying Message Structure

      The fields in Figure 3.1 are as follows:

         Ver - Group Keying protocol version. This document specifies
             version zero.

         R - Response flag. If set to one, indicates a response message.


D. Eastlake                                                     [Page 7]


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             If set to zero, indicated a request or no-op message.

         KeyID1Lngth, KeyID1 - KeyID1 identifies the stable key wrapping
             key (also known as the Key Encrypting Key (KEK)) as further
             specified in the use profile. KeyID1Lngth is a 5-bit field
             that gives the length of KeyID1 in bytes minus 1 as an
             unsigned integer.

         Use Type - Specifies the particular group security use profile
             such as one of the two profiles in [SGKPuses]. See Section
             5, Item 3.

         Pad1 Length, Pad1 - Padding to obscure the non-padded message
             size. Pad1 Length may be from 0 to 255 and gives the length
             of the padding as an unsigned integer. Each byte of padding
             MUST be equal to Pad1 Length. For example, 3 bytes of
             padding with length is 0x03030303.

         KW Algorithm - An unsigned integer 4-bit field specifying the
             Key Wrap Alogithm. See Section 5, Item 4.

         KW Length - An unsigned integer 14-bit field that gives the
             length of the Key Wrapped Material in octets.

         Key Wrapped Material - The output of the designated Key
             Wrapping Algorithm on the message vector of fields using
             the designated stable key.

   The vector of fields contained within the key wrapping is specified
   for the various keying messages in subsections below.  The contents
   of this wrapped vector are protected by the key wrapping as well as
   being authenticated and super-encrypted by the pairwise keyed
   security used for sending the overall keying message. The probability
   that the stable key used for key wrapping is the same as the outer
   message pairwise key MUST be insignificant (less that 1 in 2**64).

   Each group keying message contains, in the key wrapped vector of
   fields, a message type and a message ID set by the sender of a
   request.  These fields are returned in the corresponding response to
   assist in the matching of response to requests, except that there is
   no response required to the No-Op message.

   If no response is received to a request (other than a No-Op request)
   for an amount of time configurable in milliseconds from 1 to ( 2**15
   - 1 ), the request is re-transmitted with the same message ID.  These
   retries can occur up to a configurable number of times from 1 to 8.
   Unless otherwise provided in the particular use profile, the default
   response delay threshold is 200 milliseconds and the default maximum
   number of retries is 3.



D. Eastlake                                                     [Page 8]


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   Keying messages are sent with a priority/QoS configurable on a per
   device per use type basis. The default priority/QoS is specified in
   the use profile.

   Since the minimum length of the Key Wrapped Material is 16 bytes, the
   minimum valid length of a keying message before pairwise security is
   21 bytes, even if KeyID1 Length and Pad1 Length are zero. All multi-
   byte fields are in network order, that is, with the most significant
   byte first. The maximum valid length before pairwise security is 4
   (fixed bytes) + 32 (max KeyID1) + 255 (max padding) + 264 (max KW
   material) = 555 bytes.



3.1 Set Key Message

   The structure of the wrapped vector of fields for the Set Key keying
   message is as show in Figure 3.2. A recipient automatically
   determines the overall length provided for this vector of fields
   inside the key wrapping as a byproduct of the process of key
   unwrapping.

      +-+-+-+-+-+-+-+-+
      | Msg Type = 1  |                  1 bytes
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Msg ID                           3 bytes      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Pad2 Length   |                  1 bytes
      +-+-+-+-+-+-+-+-+...
      | Padding                          Pad2 Length bytes
      +-+-+-+-+-+-+-+-+...
      | Other                            Variable size
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Lifetime                      |  2 bytes
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | KeyID2 Length |                  1 byte
      +-+-+-+-+-+-+-+-+
      | KeyID2  ...                      KeyID2 Length bytes
      +-+-+-+-+-+-+-+-+
      | CypherSuiteLng|                  1 byte
      +-+-+-+-+-+-+-+-+
      | CypherSuite ...                  CypherSuiteLng bytes
      +-+-+-+-+-+-+-+-...
      | Key  ...                         Variable size
      +-+-+-+-+-+-+-+-...

                 Figure 3.2. Set Key Message Inner Structure





D. Eastlake                                                     [Page 9]


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      The fields are as follows:

         Msg Type = 1 for Set Key message

         Msg ID - A 3 byte quantity to be included in the corresponding
             response message to assist in matching requests and
             responses. Msg ID zero has a special meaning in responses
             and MUST NOT be used in a Set Key message or any other
             group keying request message.

         Pad2 Length, Pad2 - Padding to obscure the size of the unapdded
             AES wrapped data. Pad2 Length may be from 0 to 255 and
             gives the length of the padding as an unsigned integer.
             Each byte of padding MUST be equal to Pad1 Length. For
             example, 2 bytes of padding with length byte is 0x020202.

         Other - Additional information if specified in the use profile.
             If Other information in this message is not mentioned in
             the use profile, there is none and this portion of the
             wrapped information is null. If a use profile specifies
             Other information it must be possible to determine its
             length so that following fields can be properly parsed and
             so that the size of the Key field can be deduced; for
             example, Other could begin with a length byte.

         Lifetime - A 2-byte unsigned integer. After that number of
             seconds plus one second, the key and associated information
             being set MUST be discarded. Unless otherwise specified for
             a particular use profile of this group keying protocol, the
             default Lifetime is 15,000 seconds or a little over four
             hours.

         KeyID2 Length, KeyID2 - KeyID2 identifies the group key and
             associated information being set as further specified in
             the use profile. KeyID2 Length is an unsigned byte that
             gives the length of KeyID2 in bytes.

         CypherSuiteLng, CypherSuite - CypherSuite identifies the cypher
             suite associated with the key being set as further
             specified in the use profile. CypherSuite Length is an
             unsigned byte the gives the length of CypherSuite in bytes.

         Key - This is the actually group shared secret keying material
             being set. Its length is deduced from the overall length of
             the vector of fields (found by the key unwrap operation)
             and the length of the preceding fields.

   Keying material and associated cypher suite are indexed under the Key
   ID and the identity of the station that sent the information. This
   identity is normally the address of that station as specified in the


D. Eastlake                                                    [Page 10]


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   use profile.

   If GKs already has a dynamic key set under KeyID2, the key's value
   and associated cypher suite are compared with those in the Set Key
   messages. If they are the same, the only receiver action is to update
   the Lifetime information associated with KeyID2 and send a Response
   message. If they are different, the lifetime, cypher suite, and key
   (and possibly Other material) are replaced, the use flag is cleared,
   and a Response message sent.



3.2 Use, Delete, Disuse, or Deleted Key Messages

   The structure of the wrapped material for the Use Key, Delete Key,
   Disuse Key, and Deleted Key keying messages are the same as each
   other except for the message type and are shown in Figure 3.3

      +-+-+-+-+-+-+-+-+
      | Msg Type = t  |                  1 byte
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Msg ID                           3 bytes      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Pad2 Length   |                  1 bytes
      +-+-+-+-+-+-+-+-+...
      | Padding                          Pad2 Length bytes
      +-+-+-+-+-+-+-+-+...
      | Other                            Variable size
      +-+-+-+-+-+-+-+-+...
      | KeyID2 Length |                  1 byte
      +-+-+-+-+-+-+-+-+
      | KeyID2  ...                      KeyID2 bytes
      +-+-+-+-+-+-+-+-+

           Figure 3.3. Use, Delete, Disuse, or Deleted Key Message

      The Msg Type field specifies the particular message as follows:

      Msg Type   Message
      --------   ----------
           2     Use Key
           3     Delete Key
           4     Disuse Key
           5     Deleted Key

   The remaining fields are as specified in Section 3.1. KeyID2
   indicates the key to be used, deleted, for which use should cease, or
   which has been deleted, depending on the message type.

   It is RECOMMENDED that these messages be padded so as to be the same


D. Eastlake                                                    [Page 11]


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   length as a typical Set Key message.

   The Delete Key is sent by a station believing itself to be GKd
   instructing some GKs to delete a key.  When a GKs spontaneously
   deletes a key, it sends a Deleted Key message to the station from
   which it received the key. The message types for Delete Key and
   Deleted Key are different to minimize confusion in corner cases such
   as the GKd changing while messages are in flight. The Msg ID used in
   a Deleted Key message is created by the sending GKs from a space of
   Msg IDs associated with that GKs, which space is independent of the
   Msg IDs used in requests originated by GKd.



3.3 Response Message

   The structure of the wrapped material for the Response group keying
   message is as show below in Figure 3.4. A response message is
   indicated by the R bit in the first byte of the message outside the
   key wrapping.

   A response MUST NOT be sent due to the receipt of a response. The R
   bit is outside of the key wrapping so that this rule can be enforced
   even in cases of difficulty in unwrapping.

      +-+-+-+-+-+-+-+-+
      | Msg Type = n  |                  1 byte
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Msg ID                           3 bytes      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Pad2 Length   |                  1 bytes
      +-+-+-+-+-+-+-+-+...
      | Padding                          Pad2 Length bytes
      +-+-+-+-+-+-+-+-+...
      | Other                            Variable size
      +-+-+-+-+-+-+-+-+...
      | Response Code |                  1 byte
      +-+-+-+-+-+-+-+-+
      | ReqPartLength |                  1 byte
      +-+-+-+-+-+-+-+-+...
      | Request Part                     ReqPartLenth bytes
      +-+-+-+-+-+-+-+-...

                 Figure 3.4. Response Message Inner Structure

      Except as specified below, the fields are as specified for the Key
      Set message in Section 3.1.

         Msg Type, Msg ID - The content of these field is copied from
             the message in reply to which this Response message is sent


D. Eastlake                                                    [Page 12]


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             unless there is an error that stops the replying station
             from determining them; in that case the special value zero
             is used for the Msg Type and Msg ID. Errors where the Msg
             Type and ID could not be determined are indicated by a
             Response Code with its high order bit set to one, that is,
             the 0b1xxxxxxx bit set.

         Response Code - An unsigned byte giving the response as
             enumerated in in Section 3.3.1.  Any Response Code other
             than a success indicates that the receiver took no action
             on the request other than sending an error Response
             message.

         ReqPartLength, Request Part: It is usually usefully to include
             some or all of the request message in error responses.
             -  If the Response Code high order two bits are zero, the
                request succeeded and ReqPartLength MUST be set to zero
                so Request Part will be null.
             -  If the Response Code high order two bits are zero one
                (0b01xxxxxx), then there was an error in the part of the
                request inside the key wrapping but the unwrap process
                was successful. ReqPartLength is the length of the
                request message material included in the Request Part
                field. The included request material is from the
                unwrapped vector of fields started with the Msg Type
                byte.
             -  If the Response Code high order bit is one (the
                0b1xxxxxxx is set), then there was an error parsing the
                material outside the AES key wrap or an error in the AES
                unwrapping process. ReqPartLength is the length of the
                request message part included in the Request Part field.
                The included part of the request starts with the first
                byte of the message (the byte containing the version,
                response flag, and KeyID1 Length). The key wrapped
                material in the response message will still be wrapped.



3.3.1 Response Codes

   The high order two bits of the Response Code have meaning as shown in
   Table 3.1.

      Top 2 Bits    Category
      ----------    ----------
          0b00      Success
          0b01      AES wrap contents
          0b10/11   Outside of AES wrap contents

                  Figure 3.1 Categories of Response Codes


D. Eastlake                                                    [Page 13]


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      Response  Response
       Decimal      Hex    Meaning
      --------  --------  ----------
            0       0x00   Success
            1       0x01   Success and the key at an existing key ID was
                                 changed
         2-47  0x02-0x2F   Unassigned
        48-63  0x30-0x3F   Reserved for special success codes defined in
                                 use profiles
           64       0x40   Malformed inner fields (see Note 2 below)
           65       0x41   Unknown or zero Msg Type in a request
           66       0x42   Zero Msg ID in a request
           68       0x43   Invalid length KeyID2
           69       0x44   Unknown KeyID2
           70       0x45   Invalid length CypherSuite
           71       0x46   Unknown CyperSuite
           72       0x47   Bad Key (see Note 3 below)
       73-111  0x49-0x6F   Unassigned
      112-127  0x70-0x7F   Reserved for error codes defined in use
                                 profiles and related to the key wrapped
                                 contents
          128       0x80   Malformed message (see Note 1 below)
          129       0x81   Invalid length KeyID1
          130       0x82   Unknown KeyID1
          131       0x83   Unknown Use Type
          131       0x84   Key unwrap fails test for constant (e.g., AES
                                 test 1, see Section 3 [RFC5649]).
          132       0x85   Key unwrap fails message length versus
                                 wrapped size test (e.g., AES test 2,
                                 see Section 3 [RFC5649]).
          133       0x86   Key unwrap fails test for value of padding
                                 (e.g., AES test3, see Section 3
                                 [RFC5649]).
      134-175  0x86-0x7F   Unassigned
      176-191  0xB0-0xBF   Reserved for error codes defined in use
                                 profiles and related to parts of
                                 message outside the key wrap contents
          192       0xC0   No keys set
          193       0xC1   Referenced key unknown
          194       0xC2   Referenced key known but use flag not set
      195-255  0xC3-0xFF   Reserved

Response Code Notes:

   Note 1  Message is too short or too long, AES wrapped material is too
           short, Padding bytes are not the required value, or similar
           fundamental message format problems.

   Note 2  The key wrapped inner vector of fields is too short or too
           long, Padding bytes are not the required value, or similar


D. Eastlake                                                    [Page 14]


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           fundamental vector of fields format problems.

   Note 3  Key is not a valid length for CypherSuite or other internal
           checks on key (for example, parity bits in a 64 bit DES key
           (not that you should be using DES)) fail when they should be
           correct.

                         Figure 3.2 Response Codes




3.4 No-Op Message

   The No-Op message is a dummy message intended for use in disguising
   metadata deducable from keying message transmissions. It requires no
   response although a recipient can always decided to send a No-Op
   message to a station from which it has received such a message. The
   vector of fields inside the AES key wrap is as follows:

      +-+-+-+-+-+-+-+-+
      | Msg Type = 6  |                  1 byte
      +-+-+-+-+-+-+-+-+
      | Pad2 Length   |                  1 bytes
      +-+-+-+-+-+-+-+-+...
      | Padding                          Pad2 Length bytes
      +-+-+-+-+-+-+-+-...

                 Figure 3.5. No-Op Message Inner Structure

   The Msg Type is set to 6 to indicate a No-Op message.

   Pad2 Length and Padding are as specified in Section 3.1. It is
   RECOMMENDED that Pad2 Length in a No-Op message be such as to make
   its length the same as the length of a typical Set Key message.

















D. Eastlake                                                    [Page 15]


INTERNET-DRAFT                                       Simple Group Keying


4. Security Considerations

   This section gives some general security considerations of this group
   keying protocol as distinguished from security considerations of a
   particular use profile.

   The method by which the stations in the group discover each other is
   specified in the group keying use profile. GKd controls group access
   and generally learns whatever it needs to know about GKs during the
   pairwise authentication and pairwise keying process.

   The group keying provided by this protocol is shared secret keying.
   This means that data messages can only be authenticated as coming
   from some group member but not as coming from a specific group
   member. If this level of authentication is insufficient, GKd can
   simply not set keys or not set them as usable. This will force all
   stations in the group that are configured to use security for multi-
   destination transmissions to the group to serially unicast data to
   the other group members using pairwise keying.

   The content value of padding fields in the Group Keying protocol is
   fixed so that it cannot be used as a covert channel. It might still
   be possible to use the length of padding as a covert channel.





























D. Eastlake                                                    [Page 16]


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5. IANA Considerations

   IANA is requested to perform the following actions:

      1. Establish a protocol parameters web page for "Group Keying
         Protocol Parameters" with the initial registries on that page
         as specified below in this section.

      2. Establish a "Message Type" registry on the Group Keying
         Protocol Parameters page as follows:

         Name: Message Types Registration Procedure: IETF Review
         Reference: [this document]

             Type     Description     Reference
            -------   -----------     ---------------
                  0   Reserved                  [This document]
                  1   Set Key                   [This document]
                  2   Use Key                   [This document]
                  3   Delete Key                [This document]
                  4   Disuse Key                [This document]
                  5   Deleted Key               [This document]
                  6   No-Op                     [This document]
              7-250   Unassigned
            251-254   Reserved for Private Use  [This document]
                255   Reserved                  [This document]

      3. Establish a "Group Keying Use Profile" registry on the Group
         Keying Protocol Parameters page as follows:

         Name: Group Keying Use Profiles Registration Procedure: IETF
         Review Reference: [This document]

             Profile    Description               Reference(s)
            ---------   -----------               ------------
                   0    Reserved                  [This document]
                   1    Extended RBridge Channel  [SGKPuses]
                   2    TRILL over IP             [SGKPuses]
               3-250    Unassigned
             251-254    Reserved for Private Use  [This document]
                 255    Reserved                  [This document]

      4. Establish a "Key Wrap Algorithm" registry on the Group Keying
         Protocol Parameters page as follows:








D. Eastlake                                                    [Page 17]


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         Name: Key Wrap Algorithms Registration Procedure: IETF Review
         Reference: [This document]

            Code      Algorithm               Reference
            -----    -----------               ---------
              0      Reserved                  [This document]
              1      AES                       [RFC5649]
              2      ChaCha                    [ChaChaKW]
              3-16   -                         Unassigned
             17      Reserved                  [This document]

      5. Establish a "Response Code" registry on the Group Keying
         Protocol Parameters page as show below taking entries from the
         Response Code table in Section 3.3.1 above.  In the table of
         values, the Reference column should be "[This document]" except
         where the Meaning is "Unassigned" or "Reserved".

         Name: Response Codes Registration Procedure: IETF Review
         Reference: [This document]

         Note: The top two bits of the Response Code indicate a category
         as specified in Section 3.3.1 of [this document].

            Response    Response
             Decimal       Hex     Meaning      Reference
            --------   ---------  -----------   ---------
                  0        0x00    Success      [this document]
                ...         ...    ...
                255        0xFF    Reserved























D. Eastlake                                                    [Page 18]


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Normative References

   [RFC2119] - BBradner, S., "Key words for use in RFCs to Indicate
         Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119,
         March 1997, <http://www.rfc-editor.org/info/rfc2119>.

   [RFC5649] - Housley, R. and M. Dworkin, "Advanced Encryption Standard
         (AES) Key Wrap with Padding Algorithm", RFC 5649, DOI
         10.17487/RFC5649, September 2009, <http://www.rfc-
         editor.org/info/rfc5649>.

   [RFC6325] - Perlman, R., Eastlake 3rd, D., Dutt, D., Gai, S., and A.
         Ghanwani, "Routing Bridges (RBridges): Base Protocol
         Specification", RFC 6325, DOI 10.17487/RFC6325, July 2011,
         <http://www.rfc-editor.org/info/rfc6325>.

   [RFC6347] - Rescorla, E. and N. Modadugu, "Datagram Transport Layer
         Security Version 1.2", RFC 6347, January 2012, <http://www.rfc-
         editor.org/info/rfc6347>.

   [RFC7176] - Eastlake 3rd, D., Senevirathne, T., Ghanwani, A., Dutt,
         D., and A. Banerjee, "Transparent Interconnection of Lots of
         Links (TRILL) Use of IS-IS", RFC 7176, May 2014,
         <http://www.rfc-editor.org/info/rfc7176>.

   [RFC7780] - Eastlake 3rd, D., Zhang, M., Perlman, R., Banerjee, A.,
         Ghanwani, A., and S. Gupta, "Transparent Interconnection of
         Lots of Links (TRILL): Clarifications, Corrections, and
         Updates", RFC 7780, DOI 10.17487/RFC7780, February 2016,
         <http://www.rfc-editor.org/info/rfc7780>.

   [RFC8174] - Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
         2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May
         2017, <http://www.rfc-editor.org/info/rfc8174>.

   [SGKPuses] - D. Eastlake, D. Zhang, "Simple Group Keying Protocol
         TRILL Use Protfiles", draft-ietf-trill-link-group-keying, work
         in progress.

   [ChaChaKW] - D. Eastlake, "CHA CHA 20 Key Wrap with Padding
         Algorithm", draft-eastlake-chacha20-key-wrap.txt, work in
         progress.



Informative References

         None.




D. Eastlake                                                    [Page 19]


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Acknowledgements

   The contributions of the following are hereby gratefully
   acknowledged:

         TBD

   The document was prepared in raw nroff. All macros used were defined
   within the source file.











































D. Eastlake                                                    [Page 20]


INTERNET-DRAFT                                       Simple Group Keying


Authors' Addresses

      Donald E. Eastlake, 3rd
      Huawei Technologies
      155 Beaver Street
      Milford, MA 01757 USA

      Phone: +1-508-333-2270
      EMail: d3e3e3@gmail.com


      Dacheng Zhang
      Huawei Technologies

      Email: dacheng.zhang@huawei.com





































D. Eastlake                                                    [Page 21]


INTERNET-DRAFT                                       Simple Group Keying


Copyright, Disclaimer, and Additional IPR Provisions

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   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.  The definitive version of
   an IETF Document is that published by, or under the auspices of, the
   IETF. Versions of IETF Documents that are published by third parties,
   including those that are translated into other languages, should not
   be considered to be definitive versions of IETF Documents. The
   definitive version of these Legal Provisions is that published by, or
   under the auspices of, the IETF. Versions of these Legal Provisions
   that are published by third parties, including those that are
   translated into other languages, should not be considered to be
   definitive versions of these Legal Provisions.  For the avoidance of
   doubt, each Contributor to the IETF Standards Process licenses each
   Contribution that he or she makes as part of the IETF Standards
   Process to the IETF Trust pursuant to the provisions of RFC 5378. No
   language to the contrary, or terms, conditions or rights that differ
   from or are inconsistent with the rights and licenses granted under
   RFC 5378, shall have any effect and shall be null and void, whether
   published or posted by such Contributor, or included with or in such
   Contribution.





















D. Eastlake                                                    [Page 22]


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