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GDOI Protocol Support for IEC 62351 Security Services
draft-weis-gdoi-iec62351-9-03

The information below is for an old version of the document.
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This is an older version of an Internet-Draft that was ultimately published as RFC 8052.
Authors Brian Weis , Maik Seewald , Herb Falk
Last updated 2014-02-13
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draft-weis-gdoi-iec62351-9-03
Network Working Group                                            B. Weis
Internet-Draft                                                M. Seewald
Intended status: Standards Track                           Cisco Systems
Expires: August 17, 2014                                         H. Falk
                                                                   SISCO
                                                       February 13, 2014

         GDOI Protocol Support for IEC 62351 Security Services
                     draft-weis-gdoi-iec62351-9-03

Abstract

   The IEC 61850 power utility automation family of standards describe
   methods using Ethernet and IP for distributing control and data
   frames within and between substations.  The IEC 61850-90-5 and IEC
   62351-9 standards specify the use of the Group Domain of
   Interpretation (GDOI) protocol (RFC 6407) to distribute security
   transforms for some IEC 61850 security protocols.  This memo defines
   GDOI payloads to support those security protocols.

Status of this Memo

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

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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."

   This Internet-Draft will expire on August 17, 2014.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   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

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   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.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements notation  . . . . . . . . . . . . . . . . . .  3
     1.2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  4
     1.3.  Acronyms and Abbreviations . . . . . . . . . . . . . . . .  4

   2.  IEC 61850 Protocol Information . . . . . . . . . . . . . . . .  5
     2.1.  ID Payload . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.2.  SA TEK Payload . . . . . . . . . . . . . . . . . . . . . .  6
     2.3.  Key Download Payload . . . . . . . . . . . . . . . . . . .  9

   3.  Security Considerations  . . . . . . . . . . . . . . . . . . . 11

   4.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12

   5.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 14

   6.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
     6.1.  Normative References . . . . . . . . . . . . . . . . . . . 15
     6.2.  Informative References . . . . . . . . . . . . . . . . . . 15

   Appendix A.  Example ID, SA TEK, and KD payloads for IEC 61850 . . 17

   Appendix B.  Implementation Considerations . . . . . . . . . . . . 20
     B.1.  DER Length Fields  . . . . . . . . . . . . . . . . . . . . 20
     B.2.  Groups with Multiple Senders . . . . . . . . . . . . . . . 20

   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 21

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1.  Introduction

   Power substations use Generic Object Oriented Substation Events
   (GOOSE) protocol [IEC-61850-8-1] to distribute control information to
   groups of devices using a multicast strategy.  Sources within the
   power substations also distribute IEC 61850-9-2 sampled values data
   streams [IEC-61850-9-2].  The IEC 62351-9 standard [IEC-62351-9]
   describes key management methods for the security methods protecting
   these IEC 61850 messages, including methods of device authentication
   and authorization, and methods of policy and keying material
   agreement for IEC 61850 message encryption and data integrity
   protection.  These key management methods include the use of GDOI
   [RFC6407] to distribute the security policy and session keying
   material used to protect IEC 61850 messages when the messages are
   sent to a group of devices.

   The protection of the messages is defined within IEC 62351-6
   [IEC-62351-6], IEC 61850-8-1 [IEC-61850-8-1], and IEC 61850-9-2
   [IEC-61850-9-2].  Protected IEC 61850 messages typically include the
   output of a Message Authentication Code (MAC) and may also be
   encrypted using a symmetric cipher such as the Advanced Encryption
   Standard (AES).

   Section 5.5.2 of RFC 6407 specifies that the following information
   needs to be provided in order to fully define a new Security
   Protocol:

   o  The Protocol-ID for the particular Security Protocol.

   o  The SPI Size

   o  The method of SPI generation

   o  The transforms, attributes, and keys needed by the Security
      Protocol.

   This document defines GDOI payloads to distribute policy and keying
   material to protect IEC 61850 messages, and defines the necessary
   information to ensure interoperability between IEC 61850
   implementations.

1.1.  Requirements notation

   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].

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1.2.  Terminology

   The following key terms are used throughout this document:

   Generic Object Oriented Substation Events  Power substation control
         model defined as per IEC 61850.

   IEC 61850 message  A message in the IEC 61850 family of protocols
         carrying control or data between Substation devices.

1.3.  Acronyms and Abbreviations

   The following acronyms and abbreviations are used throughout this
   document

   AES   Advanced Encryption Standard

   CK    Current Key

   GCKS  Group Controller/Key Server

   GDOI  Group Domain of Interpretation

   GM    Group Member

   GOOSE Generic Object Oriented Substation Events

   KD    Key Download Payload

   KEK   Key Encryption Key

   MAC   Message Authentication Code

   NK    Next Key

   SA    Security Association

   SPI   Security Parameter Index

   TEK   Traffic Encryption Key

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2.  IEC 61850 Protocol Information

   The following sections describe the GDOI payload extensions that are
   needed in order to distribute security policy and keying material for
   the IEC 62351 Security Services.  The Identification (ID) Payload is
   used to describe an IEC 62351 GDOI group.  The Security Association
   (SA) Traffic Encryption Key (TEK) payload is used to describe the
   policy defined by a Group Controller/Key Server (GCKS) for a
   particular IEC 62351 traffic selector.  No changes are required to
   the Key Download (KD) Payload, but a mapping of IEC 62351 keys to KD
   Payload key types is included.

2.1.  ID Payload

   The ID payload in a GDOI GROUPKEY-PULL exchange allows the Group
   Member (GM) to declare the group it would like to join.  A group is
   defined by an ID payload as defined in GDOI [RFC6407] and reproduced
   in Figure 1.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Next Payload  !   RESERVED    !         Payload Length        !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !    ID Type    !      DOI-Specific ID Data = 0                 !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ~                       Identification Data                     ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                 Figure 1: RFC 6407 Identification Payload

   An ID Type name of ID_OID (value 13) is defined in this memo to
   specify an Object Identifier (OID) [ITU-T-X.683] encoded using
   Distinguished Encoding Rules (DER) [ITU-T-X.690].  Associated with
   the OID may be an OID Specific Payload DER encoded as further
   defining the group.  Several OIDs are specified in [IEC-62351-9] for
   use with IEC 61850.  Each OID represents a GOOSE or Sampled Value
   protocol, and in some cases IEC 61850 also specifies a particular
   multicast destination address to be described in the OID Specific
   Payload field.  The format of the ID_OID Identification Data is
   specified as shown in Figure 2.

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      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !  OID Length   !                       OID                     ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !  OID Specific Payload Length  !     OID Specific Payload      ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                   Figure 2: ID_OID Identification Data

   The ID_OID Identification Data fields are defined as follows:

   o  OID Length (1 octet) -- Length of the OID field.

   o  OID (variable) -- An ASN.1 ObjectIdentifier encoded using DER
      [ITU-T-X.690].

   o  OID Specific Payload Length (2 octets) -- Length of the OID
      Specific Payload.  Set to zero if the OID does not require an OID
      Specific Payload.

   o  OID Specific Payload (variable) -- OID specific selector encoded
      in DER.  If OID Specific Payload Length is set to zero this field
      does not appear in the ID payload.

2.2.  SA TEK Payload

   The SA TEK payload contains security attributes for a single set of
   policy associated with a group TEK.  The type of policy to be used
   with the TEK is described by a Protocol-ID field included in the SA
   TEK.  As shown in Figure 3 reproduced from RFC 6407, each Protocol-ID
   describes a particular TEK Protocol-Specific Payload definition.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Next Payload  !   RESERVED    !         Payload Length        !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Protocol-ID   !       TEK Protocol-Specific Payload           ~
     +-+-+-+-+-+-+-+-+                                               ~
     ~                                                               ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                     Figure 3: RFC 6407 SA TEK Payload

   The Protocol-ID name of GDOI_PROTO_IEC_61850 (value TBD1) is defined
   in this memo for the purposes of distributing IEC 61850 policy.  An

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   GDOI_PROTO_IEC_61850 SA TEK includes an OID and (optionally) an OID
   Specific Payload that together define the selectors for the network
   traffic.  The selector fields are followed by security policy fields
   indicating how the specified traffic is to be protected.  The
   GDOI_PROTO_IEC_61850 TEK Protocol-Specific Payload is defined as
   shown in Figure 4.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !  OID Length   !                       OID                     ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !  OID Specific Payload Length  !     OID Specific Payload      ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Current KeyID !   RESERVED    ! CK Remaining Lifetime Value   !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !          CK Auth Alg          !           CK Key Alg          !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !  Next KeyID   !   RESERVED    ! NK Remaining Lifetime Value   !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !          NK Auth Alg          !           NK Key Alg          !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                    Figure 4: IEC-61850 SA TEK Payload

   The GDOI_PROTO_IEC_61850 SA TEK Payload fields are defined as
   follows:

   o  OID Length (1 octet) -- Length of the OID field.

   o  OID (variable) -- An ASN.1 ObjectIdentifier encoded using DER.
      OIDs defined in IEC 61850 declare the type of IEC 61850 message to
      be protected, as defined by [IEC-62351-9].

   o  OID Specific Payload Length (2 octets) -- Length of the OID
      Specific Payload.  This field is set to zero if the policy does
      not include an OID Specific Payload.

   o  OID Specific Payload (variable) -- The traffic selector (e.g.,
      multicast address) specific to the OID encoded using DER.  Some
      OID policy settings do not require the use of an OID Specific
      Payload, in which case this field is not included in the TEK and
      the OID Specific Payload Length is set to zero.

   o  Current KeyID (1 octet) -- Identifier for the Current Key. This
      field represents a SPI.

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   o  RESERVED (1 octet) -- MUST be zero, and MUST be ignored on
      receipt.

   o  CK Remaining Lifetime value (2 octets) -- The number of minutes
      prior to the next scheduled Current Key change.  A value of zero
      (0) shall indicate that no key change has been scheduled.

   o  CK Auth Alg (2 octets) -- Current Key Authentication Algorithm ID.
      Valid values are define in Section 2.2.2.

   o  CK Key Alg (2 octets) -- Current Key Confidentiality Algorithm ID.
      Valid values are define in Section 2.2.3.

   o  Next KeyID (1 octet) -- Identifier for the Next Key. This field
      represents a SPI.

   o  RESERVED (1 octet) -- MUST be zero, and MUST be ignored on
      receipt.

   o  NK Remaining Lifetime value (2 octets) -- The number of minutes
      prior to the next scheduled Next Key change.  A value of zero (0)
      shall indicate that no key change has been scheduled.

   o  NK Auth Alg (2 octets) -- Next Key Authentication Algorithm ID.
      Valid values are define in Section 2.2.2.

   o  NK Key Alg (2 octets) -- Next Key Confidentiality Algorithm ID.
      Valid values are define in Section 2.2.3.

2.2.1.  Selectors

   The OID and (optionally) an OID Specific Payload that together define
   the selectors for the network traffic.  While they may match the OID
   and OID Specific Payload that the GM had previously requested in the
   ID payload, there is no guarantee that this will be the case.
   Including selectors in the SA TEK is important for at least the
   following reasons:

   o  The KS policy may direct the KS to return multiple TEKs, each
      representing different traffic selectors and it is important that
      every GM receiving the set of TEKs explicitly identify the traffic
      selectors associated with the TEK.

   o  The KS policy may include the use of a GDOI GROUPKEY-PUSH message,
      which distributes new or replacement TEKs to group members.  Since
      the GROUPKEY-PUSH message does not contain an ID payload the TEK
      definition must include the traffic selectors.

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2.2.2.  Authentication Algorithms

   This memo defines the following Authentication Algorithms for use
   with this TEK.  These algorithms are defined in [IEC-TR-61850-90-5].

   o  HMAC-SHA256-80.  Specifies the use of SHA-256 [FIPS180-3.2008]
      combined with HMAC [RFC2104].  The output is truncated to 80 bits,
      as per [RFC2104].  The key size is the size of the hash value
      produced by SHA-256 (256 bits).

   o  HMAC-SHA256-128.  Specifies the use of SHA-256 [FIPS180-3.2008]
      combined with HMAC [RFC2104].  The output is truncated to 128
      bits, as per [RFC2104].  The key size is the size of the hash
      value produced by SHA-256 (256 bits).

   o  HMAC-SHA256.  Specifies the use of SHA-256 [FIPS180-3.2008]
      combined with HMAC [RFC2104].  The key size is the size of the
      hash value produced by SHA-256 (256 bits).

2.2.3.  Confidentiality Algorithms

   This memo defines the following Confidentiality Algorithms for use
   with this TEK.  These algorithms are defined in [IEC-TR-61850-90-5].

   o  NONE.  Specifies that no Confidentiality Algorithm is to used.

   o  AES-CBC-128.  Specifies the use of AES [FIPS197] in the Cipher
      Block Chaining (CBC) mode [SP.800-38A] with a 128 bit key size.

   o  AES-CBC-256.  Specifies the use of AES [FIPS197] in the Cipher
      Block Chaining (CBC) mode [SP.800-38A] with a 256 bit key size.

2.2.4.  SPI Discussion

   As noted in Section 1, RFC 6407 requires that characteristics of a
   SPI must be defined.  A SPI in a GDOI_PROTO_IEC_61850 SA TEK is
   represented as a Key Identifier (KeyID).  It's size is 1 octet.  The
   KeyID is unilaterally chosen by the GCKS using any method chosen by
   the implementation.  However, an implementation needs to take care
   not to duplicate a KeyID value that is currently in use for a
   particular group.

2.3.  Key Download Payload

   The Key Download Payload contains group keys for the policy specified
   in the SA Payload.  It is comprised of a set of Key Packets, each of
   which hold the keying material associated with a SPI (i.e., an IEC
   61850 Key Identifier).  The RFC 6407 KD payload format is reproduced

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   in Figure 5.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Next Payload  !   RESERVED    !         Payload Length        !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Number of Key Packets         !            RESERVED2          !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ~                    Key Packets                                ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                      Figure 5: Key Download Payload

   Each Key Packet holds the keying material associated with a
   particular IEC 61850 Key Identifier, although GDOI refers to it as a
   SPI.  The keying material is described in a set of attributes
   indicating an encryption key, integrity key, etc., in accordance with
   the security policy of the group as defined by the associated SA
   Payload.  Each Key Packet has the following format, reproduced in
   Figure 6.

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !   KD Type     !   RESERVED    !            KD Length          !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !    SPI Size   !                   SPI (variable)              ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ~                    Key Packet Attributes                      ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                           Figure 6: Key Packet

   No changes are needed to GDOI in order to distribute IEC 61850 keying
   material, but the keys MUST be distributed as defined in Section 5.6
   of RFC 6407.  The KD TYPE MUST be TEK (1).  A key associated with an
   IEC 61850 Authentication Algorithm (distributed in the CK Auth Alg
   and NK Auth Alg SA TEK fields) MUST be distributed as a
   TEK_INTEGRITY_KEY attribute, and a key associated with an IEC 61850
   Confidentiality Algorithm (distributed in the CK Key Alg and NK Key
   Alg SA TEK fields) MUST be distributed as a TEK_ALGORITHM_KEY
   attribute.

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3.  Security Considerations

   GDOI is a security association (SA) management protocol for groups of
   senders and receivers.  This protocol performs authentication of
   communicating protocol participants (Group Member, Group Controller/
   Key Server).  GDOI provides confidentiality of key management
   messages, and it provides source authentication of those messages.
   GDOI includes defenses against man-in-middle, connection hijacking,
   replay, reflection, and denial-of-service (DOS) attacks on unsecured
   networks.  GDOI assumes the network is not secure and may be under
   the complete control of an attacker.  The Security Considerations
   described in RFC 6407 are relevant to the distribution of GOOSE and
   sampled values policy as defined in this memo.

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4.  IANA Considerations

   The following additions are made to the GDOI payloads registry
   [GDOI-REG].

   A new SA TEK Payload Values - Protocol-ID value is defined.  Its type
   is GDOI_PROTO_IEC_61850, with a value of TBD1.

   A new registry is added defining Auth Alg values.  The Attribute
   Class is called "IEC62351-9 Authentication Values".  The terms
   Specification Required and Private Use are to be applied as defined
   in [RFC5226].

                     Name                      Value
                     ----                       -----
                     Reserved                    0
                     HMAC-SHA256-80              1
                     HMAC-SHA256-128             2
                     HMAC-SHA256                 3
                     Specification Required   4-61439
                     Private Use            61440-65535

   A new registry is added defining Key Alg values.  The Attribute Class
   is called "IEC62351-9 Confidentiality Values".  The terms
   Specification Required and Private Use are to be applied as defined
   in [RFC5226].

                     Name                      Value
                     ----                       -----
                     Reserved                    0
                     NONE                        1
                     AES-CBC-128                 2
                     AES-CBC-256                 3
                     Specification Required   4-61439
                     Private Use            61440-65535

   A new registry for ID Types is defined for the Identification Payload
   when the DOI is GDOI.  The registry is taken from the ID Types
   registry for the IPsec DOI, which were previously assumed.  Values
   1-12 are defined identically to the equivalent values in the IPsec
   DOI.  Value 13 is defined in this memo.  The terms Specification
   Required and Private Use are to be applied as defined in [RFC5226].

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                     Name                      Value
                     ----                      -----
                     Reserved                    0
                     ID_IPV4_ADDR                1
                     ID_FQDN                     2
                     ID_USER_FQDN                3
                     ID_IPV4_ADDR_SUBNET         4
                     ID_IPV6_ADDR                5
                     ID_IPV6_ADDR_SUBNET         6
                     ID_IPV4_ADDR_RANGE          7
                     ID_IPV6_ADDR_RANGE          8
                     ID_DER_ASN1_DN              9
                     ID_DER_ASN1_GN             10
                     ID_KEY_ID                  11
                     ID_LIST                    12
                     ID_OID                     13
                     Specification Required  14-61439
                     Private Use            61440-65535

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5.  Acknowledgements

   The authors thanks Sean Turner, Steffen Fries, and Yoav Nir for their
   thoughtful reviews, each of which resulted in substantial
   improvements to the memo.

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6.  References

6.1.  Normative References

   [IEC-62351-9]
              International Electrotechnical Commission, "IEC 62351 Part
              9 - Key Management", IEC 62351-9 , January 2013.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", BCP 26, RFC 5226,
              May 2008.

   [RFC6407]  Weis, B., Rowles, S., and T. Hardjono, "The Group Domain
              of Interpretation", RFC 6407, October 2011.

6.2.  Informative References

   [FIPS180-3.2008]
              National Institute of Standards and Technology, "Secure
              Hash Standard", FIPS PUB 180-3, October 2008, <http://
              csrc.nist.gov/publications/fips/fips180-3/
              fips180-3_final.pdf>.

   [FIPS197]  "Advanced Encryption Standard (AES)", United States of
              America, National Institute of Science and
              Technology, Federal Information Processing Standard (FIPS)
              197, November 2001.

   [GDOI-REG]
              Internet Assigned Numbers Authority, "Group Domain of
              Interpretation (GDOI) Payload Type Values", IANA Registry,
              December 2004, <http://www.iana.org/assignments/
              gdoi-payloads/gdoi-payloads.xml>.

   [IEC-61850-8-1]
              International Electrotechnical Commission, "Specific
              Communication networks and systems for power utility
              automation - Part 8-1: Specific communication service
              mapping (SCSM) - Mappings to MMS (ISO 9506-1 and ISO
              9506-2) and to ISO/IEC 8802-3", IEC-61850-8-1 , June 2011.

   [IEC-61850-9-2]
              International Electrotechnical Commission, "Communication
              networks and systems for power utility automation - Part
              9-2: Specific communication service mapping (SCSM) -

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              Sampled values over ISO/IEC 8802-3", IEC-61850-2 ,
              September 2011.

   [IEC-62351-6]
              International Electrotechnical Commission, "Power systems
              management and associated information exchange - Data and
              communications security - Part 6: Security for IEC 61850",
              IEC-62351-6 , June 2007.

   [IEC-TR-61850-90-5]
              International Electrotechnical Commission, "Communication
              networks and systems for power utility automation - Part
              90-5: Use of IEC 61850 to transmit synchrophasor
              information according to IEEE C37.118", IEC 62351-9 ,
              May 2012.

   [ITU-T-X.683]
              "Information technology - Abstract Syntax Notation One
              (ASN.1): Parameterization of ASN.1 specifications", SERIES
              X: DATA NETWORKS AND OPEN SYSTEM COMMUNICATIONS OSI
              networking and system aspects - Abstract Syntax Notation
              One (ASN.1) , July 2002, <http://www.itu.int/ITU-T/
              studygroups/com17/languages/X.683-0207.pdf>.

   [ITU-T-X.690]
              "Information technology-ASN.1 encoding rules:
              Specification of Basic Encoding Rules (BER), Canonical
              Encoding Rules (CER) and Distinguished Encoding Rules
              (DER)", SERIES X: DATA NETWORKS, OPEN SYSTEM
              COMMUNICATIONS AND       SECURITY OSI networking and
              system aspects - Abstract Syntax       Notation One
              (ASN.1) , 2008,
              <https://www.itu.int/rec/T-REC-X.690-200811-I>.

   [RFC2104]  Krawczyk, H., Bellare, M., and R. Canetti, "HMAC: Keyed-
              Hashing for Message Authentication", RFC 2104,
              February 1997.

   [SP.800-38A]
              Dworkin, M., "Recommendation for Block Cipher Modes of
              Operation", United States of America, National Institute
              of Science and Technology, NIST Special Publication 800-
              38A 2001 Edition, December 2001.

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Appendix A.  Example ID, SA TEK, and KD payloads for IEC 61850

   An IED begins a GROUPKEY-PULL exchange and requests keys and security
   policy for 61850_UDP_ADDR_GOOSE (OID = 1.2.840.10070.61850.8.1.2 as
   defined in [IEC-61850-9-2]) and IP multicast address 233.252.0.1
   encoded as specified in [IEC-61850-9-2].

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Next Payload  !   RESERVED    !         Payload Length        !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! ID Type=13    !     DOI-Specific ID Data = 0                  !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! OID Len=13    ! OID=<06 0B 2A 86 48 CE 56 83 E3 1A 08 01 02>  ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! OID Specific Payload Len      ! OID SP=<DER for 233.252.0.1>  ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                       Sample Identification Payload

   The Key Server responds with the following SA TEK payload including a
   single GDOI_PROTO_IEC_61850 Protocol-Specific TEK payload in the
   second GROUPKEY-PULL message.

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      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Next Payload  !   RESERVED    !         Payload Length        !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !                             DOI = 2                           !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !                         Situation = 0                         !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! SA Attr NP=16 (SA TEK)        !          RESERVED2            !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Prot-ID=TBD1  !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! OID Len=13    ! OID=<06 0B 2A 86 48 CE 56 83 E3 1A 08 01 02>  ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! OID Specific Payload Len      !OID SP=<DER for 233.252.0.1>   ~
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Cur KeyID=1   !   RESERVED    ! CK Remaining Lifetime=0x3600  !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! CK AuthAlg=1 (HMAC-SHA256-80) !  CK Key Alg=2  (AES-CBC-128)  !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !  Next KeyID=2 !   RESERVED    ! NK Remaining Lifetime=0xffff  !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! CK AuthAlg=2 (HMAC-SHA256-128)!  CK Key Alg=1  (NONE)         !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                       Sample IEC-61850 SA  Payload

   The IED acknowledges that it is capable and willing to use this
   policy in the third GROUPKEY-PULL message.  In response the KS sends
   a KD payload to the requesting IED.  This concludes the GROUPKEY-PULL
   exchange.

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      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Next Payload  !   RESERVED    !         Payload Length        !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! Number of Key Packets=2       !            RESERVED2          !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !   KD Type=1   !   RESERVED    !            KD Length=62       !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !    SPI Size=1 !      SPI=1    !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! TYPE=TEK_INTEGRITY_KEY (2)    ! LENGTH=32 (256-bit key)       !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !                                                               !
     !                                                               !
     !                                                               !
     !                        HMAC-SHA256 Key                        !
     !                                                               !
     !                                                               !
     !                                                               !
     !                                                               !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! TYPE=TEK_ALGORITHM_KEY (1)    ! LENGTH=16                     !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !                                                               !
     !                        AES-CBC-128 Key                        !
     !                                                               !
     !                                                               !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !   KD Type=1   !   RESERVED    !            KD Length=42       !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !    SPI Size=1 !      SPI=2    !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     ! TYPE=TEK_INTEGRITY_KEY (2)    ! LENGTH=32 (256-bit key)       !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!
     !                                                               !
     !                                                               !
     !                                                               !
     !                        HMAC-SHA256 Key                        !
     !                                                               !
     !                                                               !
     !                                                               !
     !                                                               !
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-!

                        Sample Key Download Payload

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Appendix B.  Implementation Considerations

   Several topics have been suggested as useful for implementors.

B.1.  DER Length Fields

   The ID and SA TEK payloads defined in this memo include explicit
   lengths for fields formatted as DER.  This includes the OID Length
   and OID Specific Payload Length fields shown in Figure 2 and
   Figure 4.  Strictly speaking, these lengths are redundant since the
   length of the DER value is also encoded within the DER fields.  It
   would be possible to determine the lengths of the fields from those
   encoded values.  However, many implementations will find the explicit
   length fields convenient when constructing and sanity checking the
   GDOI messages including these payloads.  Implementations will thus be
   spared from manipulating the DER itself when performing activities
   that do not otherwise require parsing in order to obtain values
   therein.

B.2.  Groups with Multiple Senders

   GCKS policy may specify more than one protected type of IEC 61850
   message within a GDOI group.  This is represented within a GDOI SA
   Payload by the presence of an SA TEK Payload for each multicast group
   that is protected as part of group policy.  The OID contained in each
   of the SA TEK Payloads may be identical, but the value of each OID
   Specific Payload would be unique.

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Authors' Addresses

   Brian Weis
   Cisco Systems
   170 W. Tasman Drive
   San Jose, California  95134-1706
   USA

   Phone: +1 408 526 4796
   Email: bew@cisco.com

   Maik Seewald
   Cisco Systems
   Am Soeldnermoos 17
   D-85399 Hallbergmoos,
   Germany

   Phone: +49 619 6773 9655
   Email: maseewal@cisco.com

   Herb Falk
   SISCO
   6605 19-1/2 Mile Road
   Sterling Heights, MI  48314
   USA

   Phone: +1 586 254 0020 x105
   Email: herb@sisconet.com

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