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Versions: 00 01 02 03 04 05 06 07 08 09 10 11 RFC 5480

PKIX WG                                               Sean Turner, IECA
Internet Draft                                   Daniel Brown, Certicom
Intended Status: Standard Track                   Kelvin Yiu, Microsoft
Updates: 3279 (once approved)              Russ Housley, Vigil Security
Expires: September 11, 2008                              Tim Polk, NIST
                                                         March 11, 2008


        Elliptic Curve Cryptography Subject Public Key Information
                 draft-ietf-pkix-ecc-subpubkeyinfo-04.txt


Status of this Memo

   By submitting this Internet-Draft, each author represents that any
   applicable patent or other IPR claims of which he or she is aware
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   This Internet-Draft will expire on September 11, 2008.

Copyright Notice

   Copyright (C) The IETF Trust (2008).

Abstract

   This document specifies the syntax and semantics for the Subject
   Public Key Information field in certificates that support Elliptic
   Curve Cryptography.  This document updates RFC 3279.





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Table of Contents

   1. Introduction...................................................2
      1.1. Terminology...............................................3
   2. Subject Public Key Information Fields..........................3
      2.1. Elliptic Curve Public Key Algorithm Identifier............4
         2.1.1. Unrestricted Identifiers and Parameters..............5
            2.1.1.1. Named Curve.....................................5
            2.1.1.2. Specified Curve.................................7
               2.1.1.2.1. Specified Curve Version....................8
               2.1.1.2.2. Field Identifiers..........................8
                  2.1.1.2.2.1. Prime-p...............................9
                  2.1.1.2.2.2. Characteristic-two...................10
               2.1.1.2.3. Curve.....................................12
               2.1.1.2.4. Base......................................12
               2.1.1.2.5. Hash......................................12
         2.1.2. Restricted Algorithm Identifiers and Parameters.....14
      2.2. Subject Public Key.......................................15
   3. KeyUsage Bits.................................................15
   4. Security Considerations.......................................16
   5. IANA Considerations...........................................16
   6. References....................................................16
      6.1. Normative References.....................................16
      6.2. Informative References...................................17
   Appendix A. ASN.1 Module.........................................17

1. Introduction

   This document specifies the format of the subjectPublicKeyInfo field
   in X.509 certificates [RFC3280] that use Elliptic Curve Cryptography
   (ECC).  It updates [RFC3279]. This document specifies the encoding
   formats for public keys used with the following ECC algorithms:

      Elliptic Curve Digital Signature Algorithm (ECDSA);

      Elliptic Curve Diffie-Hellman (ECDH) family schemes; and,

      Elliptic Curve Menezes-Qu-Vanstone (ECMQV) family schemes.

   Two methods for specifying the algorithms that can be used with the
   subjectPublicKey are defined.  One method does not restrict the
   algorithms the key can be used with while the other method does
   restrict the algorithms the key can be used with.  To promote
   interoperability, this document indicates which is required to
   implement.




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   Three methods for specifying the algorithm's parameters are also
   defined.  One allows for complete specification of the Elliptic Curve
   (EC), one allows for the EC to be identified by an object identifier,
   and one allows for the EC to be inherited from the issuer's
   certificate. To promote interoperability, this document indicates
   which options are required to implement.

   Specification of all EC parameters is complicated with many options.
   To promote interoperability, this document indicates which options
   are required to implement.

1.1. Terminology

   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].

2. Subject Public Key Information Fields

   In the X.509 certificate, the subjectPublicKeyInfo field has the
   SubjectPublicKeyInfo type, which has the following ASN.1 syntax:

     SubjectPublicKeyInfo  ::=  SEQUENCE  {
       algorithm         AlgorithmIdentifier {{ECPKAlgorithms}},
       subjectPublicKey  BIT STRING
     }

   The fields in SubjectPublicKeyInfo have the following meanings:

      algorithm is the algorithm identifier and algorithm parameters
      for the ECC public key.  See paragraph 2.1.

      subjectPublicKey is the ECC public key.  See paragraph 2.2.

   The class ALGORITHM parameterizes the AlgorithmIdentifier type with
   sets of legal values (this class is used in many places in this
   document):

     ALGORITHM ::= CLASS {
       &id     OBJECT IDENTIFIER UNIQUE,
       &Type   OPTIONAL
     }
      WITH SYNTAX { OID &id [PARMS &Type] }

   The type AlgorithmIdentifier is parameterized to allow legal sets of
   values to be specified by constraining the type with an information
   object set. There are two parameterized types for AlgorithmIdentifier


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   defined in this document: ECPKAlgorithms (see paragraph 2.1) and
   HashFunctions (see paragraph 2.1.1.2.5).

     AlgorithmIdentifier {ALGORITHM:IOSet} ::= SEQUENCE {
       algorithm   ALGORITHM.&id({IOSet}),
       parameters  ALGORITHM.&Type({IOSet}{@algorithm}) OPTIONAL
     }

   The fields in AlgorithmIdentifier have the following meaning:

      algorithm identifies a cryptographic algorithm.  The OBJECT
      IDENTIFIER component identifies the algorithm.  The contents of
      the optional parameters field will vary according to the
      algorithm identified.

      parameters, which is optional, varies based on the algorithm
      identified.

2.1. Elliptic Curve Cryptography Public Key Algorithm Identifiers

   The algorithm field in the SubjectPublicKeyInfo structure indicates
   the algorithms and any associated parameters for the ECC public key
   (see paragraph 2.2).   The algorithms are restricted to the
   ECPKAlgorithms parameterized type, which uses the following ASN.1
   structure:

     ECPKAlgorithms ALGORITHM ::= {
       ecPublicKeyType |
       ecDH |
       ecMQV,
       ... -- Extensible
     }

   The algorithms defined are as follows:

      ecPublicKeyType indicates that the algorithms that can be used
      with the subject public key are not restricted (i.e., they are
      unrestricted).   The key is only restricted by the values
      indicated in the key usage certificate extension.  The
      ecPublicKeyType MUST be supported.  See paragraph 2.1.1. This
      value is also used when a key is used with ECDSA.

      ecDH and ecMQV MAY be supported.  See paragraph 2.1.2.






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2.1.1. Unrestricted Identifiers and Parameters

   The "unrestricted" algorithm is defined as follows:

    ecPublicKeyType ALGORITHM ::= {
       OID id-ecPublicKey PARMS ECParameters }

   The algorithm identifier is:

     id-ecPublicKey OBJECT IDENTIFIER ::= {
       iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2) 1 }

   The parameters for id-ecPublicKey are as follows:

     ECParameters ::= CHOICE {
       namedCurve      CURVE.&id({NamedCurve}),
       specifiedCurve  SpecifiedCurve,
       implicitCurve   NULL
     }

   The fields in ECParameters have the following meanings:

      namedCurve allows all the required values for a particular set of
      elliptic curve domain parameters to be represented by an object
      identifier.  This choice MUST be supported. See paragraph
      2.1.1.1.

      specifiedCurve allows all of the required values to be explicitly
      specified.  This choice MAY be supported, and if it is,
      implicitCurve MUST also be supported.  See paragraph 2.1.1.2.

      implicitCurve allows the elliptic curve parameters to be
      inherited from the issuer's certificate.  This choice MAY be
      supported, but if subordinate certificates use the same
      namedCurve as their superior, then the subordinate certificate
      MUST use the namedCurve option. That is, implicitCurve is only
      supported if the superior doesn't use the namedCurve option.

2.1.1.1. Named Curve

   The namedCurve field in ECParameters uses the class CURVE to
   constrain the set of legal values from NamedCurve, which are object
   identifiers:

     CURVE ::= CLASS { &id OBJECT IDENTIFIER UNIQUE }
       WITH SYNTAX { ID &id }



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   The NamedCurve parameterized type is defined as follows:

     NamedCurve CURVE ::= {
      { ID secp192r1 } | { ID sect163k1 } | { ID sect163r2 } |
      { ID secp224r1 } | { ID sect233k1 } | { ID sect233r1 } |
      { ID secp256r1 } | { ID sect283k1 } | { ID sect283r1 } |
      { ID secp384r1 } | { ID sect409k1 } | { ID sect409r1 } |
      { ID secp521r1 } | { ID sect571k1 } | { ID sect571r1 },
      ... -- Extensible
     }

   The curve identifiers are the fifteen NIST recommended curves:

   secp192r1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2)
     curves(3) prime(1) 1 }

   sect163k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 1 }

   sect163r2 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 15 }

   secp224r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 33 }

   sect233k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 26 }

   sect233r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 27 }

   secp256r1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2)
     curves(3) prime(1) 7 }

   sect283k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 16 }

   sect283r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 17 }

   secp384r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 34 }

   sect409k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 36 }


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   sect409r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 37 }

   secp521r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 35 }

   sect571k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 38 }

   sect571r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 39 }

2.1.1.2. Specified Curve

   The specifiedCurve field in ECParameters is of SpecifiedCurve type.
   SpecifiedCurve uses the following ASN.1 structure:

     SpecifiedCurve ::= SEQUENCE {
       version  SpecifiedCurveVersion
                      ( ecpVer1 | ecpVer2 | ecpVer3 ),
       fieldID  FieldID {{FieldTypes}},
       curve    Curve,            -- Curve E
       base     ECPoint,          -- Base point P
       order    INTEGER,          -- Order n of the base point
       cofactor INTEGER OPTIONAL, -- The integer h = #E(Fq)/n
       hash     HashAlgorithm OPTIONAL,
       ...                        -- Extensible
     }

   The fields in SpecifiedCurve have the following meaning:

      version specifies the version number of the elliptic curve
      parameters.  See paragraph 2.1.1.2.1.

      fieldID identifies the finite field over which the elliptic
      curve, specified in the curve field, is defined.  See paragraph
      2.1.1.2.2.

      curve specifies the elliptic curve E.  See paragraph 2.1.1.2.3.

      base specifies the base point P on the elliptic curve E,
      specified in the curve field.  See paragraph 2.1.1.2.4.

      order specifies the order n of the base point P, specified in
      base.




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      cofactor is the order of the curve, specified in the curve field,
      divided by the order, specified in the order field, of the base
      point, specified in the base field (i.e., h = #E(Fq)/n).
      Inclusion of the cofactor is optional; however, it is strongly
      RECOMMENDED that that the cofactor be included in order to
      facilitate interoperability between implementations.

      hash is the hash algorithm used to generate the elliptic curve E,
      specified in the curve field, and/or base point P, specified in
      the base field, verifiably pseudorandomly.  If the hash field is
      omitted, then the hash algorithm shall be SHA1.  See paragraph
      2.1.1.2.5.

   SpecifiedCurve is extensible and other documents may specify
   additional fields for this ASN.1 structure.

2.1.1.2.1. Specified Curve Version

   The version field in SpecifiedCurve is of SpecifiedCurveVersion type.
   SpecifiedCurveVersion uses the following ASN.1 structure:

     SpecifiedCurveVersion ::= INTEGER {
       ecpVer1(1),
       ecpVer2(2),
       ecpVer3(3)
     }

   SpecfifiedCurveVersion is ecdpVer1, ecdpVer2, or ecdpVer3.  If
   version is ecdpVer1, then the elliptic curve may or may not be
   verifiably pseudorandomly according to whether curve.seed (see
   paragraph 2.1.1.2.3) is present, and the base point P (see paragraph
   2.1.1.2.4) is not generated verifiably pseudorandomly. If version is
   ecdpVer2, then the curve and the base point P shall be generated
   verifiably pseudorandomly, and curve.seed shall be present. If
   version is ecdpVer3, then the curve is not generated verifiably
   pseudorandomly but the base point P shall be generated verifiably
   pseudorandomly from curve.seed, which shall be present.

   SpecifiedCurveVersion is extensible and other documents can specify
   additional values for SpecifiedCurveVersion.

   Implementations of this document MUST support ecpVer1.

2.1.1.2.2. Field Identifiers

   The fieldID field in SpecifiedCurve is of FieldID type. Finite fields
   are represented by values of the parameterized type FieldID,


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   constrained to the values of the objects defined in the information
   object set FieldTypes.

   The type FIELD-ID is defined by the following:

     FIELD-ID ::= TYPE-IDENTIFIER

   The FieldID parameterized type is defined as follows:

     FieldID { FIELD-ID:IOSet } ::= SEQUENCE {
       fieldType FIELD-ID.&id({IOSet}),
       parameters FIELD-ID.&Type({IOSet}{@fieldType})
     }

   Field types are given in the following information object set:

     FieldTypes FIELD-ID ::= {
       { Prime-p IDENTIFIED BY prime-field } |
       { Characteristic-two IDENTIFIED BY characteristic-two-field },
       ... -- Extensible
     }

   Two FieldTypes are defined herein: prime-p (see paragraph
   2.1.1.2.2.1) and characteristic-two (see paragraph 2.1.1.2.2.2).
   Implementations claiming conformance to this specification MUST
   support the prime-p field type and MAY support the characteristic-two
   field type.  FieldTypes is extensible and other documents can specify
   additional values for FieldTypes.

2.1.1.2.2.1. Prime-p

   A prime finite field is specified in FieldID.fieldType by the
   following object identifier:

     prime-field OBJECT IDENTIFIER ::= {
       iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(1) 1 }

   The prime finite field parameters specified in FIELD-ID parameters
   has the following ASN.1 structure:

     Prime-p ::= INTEGER

   Prime-p is an integer which is the size of the field.






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2.1.1.2.2.2. Characteristic-two

   A characteristic-two finite field is specified in FieldID.fieldType
   by the following object identifier:

     characteristic-two-field OBJECT IDENTIFIER ::= {
       iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(1) 2 }

   The characteristic-two finite field parameters specified in
   FieldID.parameters have the following ASN.1 structure:

     Characteristic-two ::= SEQUENCE {
       m INTEGER, -- Field size 2^m
       basis CHARACTERISTIC-TWO.&id({BasisTypes}),
       parameters CHARACTERISTIC-TWO.&Type({BasisTypes}{@basis})
     }

   The fields in Characteristic-two have the following meanings:

      m is the size of the field.

      basis is the type of basis used to express elements of the field.

      parameters is the polynomial used to generate the field.  The
      parameters vary based on the basis.

   The type CHARACTERISTIC-TWO is defined by the following:

     CHARACTERISTIC-TWO ::= TYPE-IDENTIFIER

   The characteristic-two field basis types are given in the following
   information object set:

     BasisTypes CHARACTERISTIC-TWO ::= {
       { NULL        IDENTIFIED BY gnBasis } |
       { Trinomial   IDENTIFIED BY tpBasis } |
       { Pentanomial IDENTIFIED BY ppBasis },
       ...  -- Extensible
     }

   Three basis types are defined herein: normal bases, trinomial bases,
   and pentanomial bases.  Implementation claiming conformance to this
   document MUST support normal basis and MAY support trimonial and
   pentanomial bases.  BasisTypes is extensible and other documents can
   specify additional values for BasisTypes.




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   Normal bases are specified in the basis field by the object
   identifier:

     gnBasis OBJECT IDENTIFIER ::= {
       iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(2)
       characteristic-two-basis(2) 1 }

   A normal base has NULL parameters.

   A trinomial base specifies the degree of the middle term in the
   defining trinomial. A trinomial base is identified in the basis field
   by the object identifier:

     tpBasis OBJECT IDENTIFIER ::= {
       iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(2)
       characteristic-two-basis(2) 2 }

   A trinomial base has the following parameters:

     Trinomial ::= INTEGER

   A pentanomial base specifies the degrees of the three middle terms in
   the defining pentanomial.  A pentanomial base is identified in the
   basis field by the object identifier:

     ppBasis OBJECT IDENTIFIER ::= {
       iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(2)
       characteristic-two-basis(2) 3 }

   A pentanomial base has the following parameters:

     Pentanomial ::= SEQUENCE {
       k1 INTEGER, -- k1 > 0
       k2 INTEGER, -- k2 > k1
       k3 INTEGER  -- k3 > k2
     }













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2.1.1.2.3. Curve

   The curve field in SpecifiedCurve is of Curve type.  Curve uses the
   following ASN.1 structure:

     Curve ::= SEQUENCE {
       a     FieldElement,
       b     FieldElement,
       seed  BIT STRING OPTIONAL
       -- Shall be present if used in SpecifiedCurve
       -- with version of ecdpVer2 or ecdpVer3
     }

     FieldElement ::= OCTET STRING

   The fields in Curve have the following meanings:

      a and b are the coefficients a and b, respectively, of the
      elliptic curve E. Each coefficient, a and b, shall be represented
      as a value of type FieldElement.  Conversion routines for field
      element to octet string are found in [SEC1].

      seed is an optional parameter that is used to derive the
      coefficients of a randomly generated elliptic curve.  seed MUST
      be present if SpecifiedECDomain is either ecdpVer2 or ecdpVer3.

2.1.1.2.4. Base

   The base field in SpecifiedCurve is of ECPoint type.  ECPoint uses
   the following ASN.1 syntax:

     ECPoint ::= OCTET STRING

   The contents of ECPoint is the octet string representation of an
   elliptic curve point.  Conversion routines for point to octet string
   are found in [SEC1]. Note that these octet strings may represent an
   elliptic curve point in compressed or uncompressed form.
   Implementations that support elliptic curve according to this
   document MUST support the uncompressed form and MAY support the
   compressed form.

2.1.1.2.5. Hash

   The hash field in SpecifiedCurve is of HashAlgorithm type.
   HashAlgorithm uses the following ASN.1 syntax:

     HashAlgorithm ::= AlgorithmIdentifier {{HashFunctions}}


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   HashAlgorithm is restricted to the HashFunctions parameterized type,
   which uses the following ASN.1 structure:

     HashFunctions ALGORITHM ::= {
       sha1   |
       sha224 |
       sha256 |
       sha384 |
       sha512,
       ... -- Extensible
     }

   The SHA1 [SHS] algorithm is defined as follows:

     sha1 ALGORITHM ::= {
       OID id-sha1 PARMS NULL }

   The algorithm identifier is:

      id-sha1 OBJECT IDENTIFIER ::= {
        iso(1) identified-organization(3) oiw(14) secsig(3)
        algorithm(2) 26 }

   The SHA224 [SHS] algorithm is defined as follows:

     sha224 ALGORITHM ::= {
       OID id-sha224 PARMS NULL }

   It has the following object identifier:

     id-sha224 OBJECT IDENTIFIER ::= {
       joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
       csor(3) nistalgorithm(4) hashalgs(2) 4 }

   The SHA256 [SHS] algorithm is defined as follows:

     sha256 ALGORITHM ::= {
     OID id-sha256 PARMS NULL }

   The algorithm identifier is:

     id-sha256 OBJECT IDENTIFIER ::= {
       joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
       csor(3) nistalgorithm(4) hashalgs(2) 1 }





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   The SHA384 [SHS] algorithm is defined as follows:

     sha384 ALGORITHM ::= {
       OID id-sha384 PARMS NULL }

   The algorithm identifier is:

     id-sha384 OBJECT IDENTIFIER ::= {
       joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
       csor(3) nistalgorithm(4) hashalgs(2) 2 }

   The SHA512 [SHS] algorithm is defined as follows:

     sha512 ALGORITHM ::= {
       OID id-sha512 PARMS NULL }

   The algorithm identifier is:

     id-sha512 OBJECT IDENTIFIER ::= {
        joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
        csor(3) nistalgorithm(4) hashalgs(2) 3 }

   An implementation of this document SHOULD accept values of the
   parameterized type HashAlgorithm that have no parameters (also called
   absent) and values that have NULL parameters. These values SHALL be
   treated equally. (Of course, future extensions to the type parameter
   HashFunctions might include information objects whose parameters
   field is more meaningful.) An implementation of this document SHOULD
   omit (leave absent) the parameters unless the recipient
   implementation is unable to process absent parameters correctly.

2.1.2. Restricted Algorithm Identifiers and Parameters

   Algorithms used with elliptic curve cryptography fall in to different
   categories: signature and key agreement algorithms.  ECDSA uses the
   ecPublicKey described in 2.1.1. Two sets of key agreement algorithms
   are identified herein: the Elliptic Curve Diffie-Hellman (ECDH) key
   agreement scheme and the Elliptic Curve Menezes-Qu-Vanstone (ECMQV)
   key agreement scheme. All algorithms are identified by an OID and
   have PARMS.  The OID varies based on the algorithm but the PARMS are
   always ECParameters (see paragraph 2.1.1).

   The ECDH is defined as follows:

     ecDH ALGORITHM ::= {
       OID id-ecDH PARMS ECParameters }



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   The algorithm identifier is:

     id-ecDH OBJECT IDENTIFIER ::= {
       iso(1) identified-organization(3) certicom(132) schemes(1)
       ecdh(12) }

   The ECMQV is defined as follows:

     ecMQV ALGORITHM ::= {
       OID id-ecMQV PARMS ECParameters }

   The algorithm identifier is:

     id-ecMQV OBJECT IDENTIFIER ::= {
       iso(1) identified-organization(3) certicom(132) schemes(1)
       ecmqv(13) }

2.2. Subject Public Key

   The subjectPublicKey from SubjectPublicKeyInfo is the ECC public key.
   Implementations of elliptic curve cryptography according to this
   document MUST support the uncompressed form and MAY support the
   compressed form of the ECC public key.  As specified in [SEC1]:

      The first byte of the key indicates whether the key is compressed
      or uncompressed.

      The elliptic curve public key (a value of type ECPoint which is
      an OCTET STRING) is mapped to a subjectPublicKey (a value of type
      BIT STRING) as follows: the most significant bit of the OCTET
      STRING value becomes the most significant bit of the BIT STRING
      value, and so on; the least significant bit of the OCTET STRING
      becomes the least significant bit of the BIT STRING.

3. KeyUsage Bits

   If the keyUsage extension is present in a CA certificate that
   indicates id-ecPublicKey in subjectPublicKeyInfo, any combination of
   the following values MAY be present:

     digitalSignature;
     nonRepudiation;
     keyAgreement;
     keyCertSign; and
     cRLSign.




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   If the CA certificate keyUsage extension asserts keyAgreement then it
   MAY assert either encipherOnly or decipherOnly.  However, this
   specification RECOMMENDS that if keyCertSign or cRLSign is present,
   keyAgreement, encipherOnly, and decipherOnly SHOULD NOT be present.

   If the keyUsage extension is present in an EE certificate that
   indicates id-ecPublicKey in subjectPublicKeyInfo, any combination of
   the following values MAY be present:

     digitalSignature;
     nonRepudiation; and
     keyAgreement.

   If the EE certificate keyUsage extension asserts keyAgreement then it
   MAY assert either encipherOnly or decipherOnly.

   If the keyUsage extension is present in a certificate that indicates
   ecDH or ecMQV in subjectPublicKeyInfo, keyAgreement MUST be present
   and digitalSignature, nonRepudiation, keyTransport, keyCertSign, and
   cRLSign MUST NOT be present. If this certificate keyUsage extension
   asserts keyAgreement then it MAY assert either encipherOnly or
   decipherOnly.

4. Security Considerations

   The security considerations in [RFC3279] apply. No new security
   considerations are introduced by this document.

5. IANA Considerations

   None.  Please remove this section prior to publication as an RFC.

6. References

6.1. Normative References

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

   [RFC3280]   Housley, R., Polk, W., Ford, W., and D. Solo, "Internet
               X.509 Public Key Infrastructure Certificate and
               Certification Revocation List (CRL) Profile", RFC 3280,
               April 2002.

   [SHS]       National Institute of Standards and Technology (NIST),
               FIPS Publication 180-2: Secure Hash Standard, 2002.



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   [SEC1]      Standards for Efficient Cryptography, "SEC 1: Elliptic
               Curve Cryptography", Version 1.0, September 2000.

   [X.680]     ITU-T Recommendation X.680: Information Technology -
               Abstract Syntax Notation One, 1997.

   [X.681]     ITU-T Recommendation X.680: Information Technology -
               Abstract Syntax Notation One: Information Object
               Spcification, 1997.

6.2. Informative References

   [RFC3279]   Polk, W., Housley, R. and L. Bassham, "Algorithm
               Identifiers for the Internet X.509 Public Key
               Infrastructure", RFC 3279, April 2002.

Appendix A. ASN.1 Module

   Appendix A.1 provides the normative ASN.1 definitions for the
   structures described in this specification using ASN.1 as defined in
   [X.680,X.681].

   PKIXECCSubPubKeyInfo { iso(1) identified-organization(3) dod(6)
     internet(1) security(5) mechanisms(5) pkix(7) id-mod(0) TBD }

   DEFINITIONS EXPLICIT TAGS ::=

   BEGIN

   -- EXPORTS ALL

   -- IMPORTS NONE

   SubjectPublicKeyInfo  ::=  SEQUENCE  {
     algorithm         AlgorithmIdentifier {{ECPKAlgorithms}},
     subjectPublicKey  BIT STRING
   }












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   ALGORITHM ::= CLASS {
     &id     OBJECT IDENTIFIER UNIQUE,
     &Type   OPTIONAL
   }
   WITH SYNTAX { OID &id [PARMS &Type] }

   AlgorithmIdentifier {ALGORITHM:IOSet} ::= SEQUENCE {
     algorithm   ALGORITHM.&id({IOSet}),
     parameters  ALGORITHM.&Type({IOSet}{@algorithm}) OPTIONAL
   }

   ECPKAlgorithms ALGORITHM ::= {
     ecPublicKeyType |
     ecDH |
     ecMQV,
     ... -- Extensible
   }

   -- Sec 2.1.1 Unrestricted Algorithms and Parameters (including ECDSA)

   ecPublicKeyType ALGORITHM ::= {
     OID id-ecPublicKey PARMS ECParameters }

   id-ecPublicKey OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2) 1 }

   -- Sec 2.1.2 Restricted Algorithms and Parameters

   ecDH ALGORITHM ::= {
     OID id-ecDH PARMS ECParameters }

   id-ecDH OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) schemes(1)
     ecdh(12) }

   -- Sec 2.1.2 Restricted Algorithms and Parameters

   ecMQV ALGORITHM ::= {
     OID id-ecMQV PARMS ECParameters }

   id-ecMQV OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) schemes(1)
     ecmqv(13) }






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   -- Parameters for both Restricted and Unrestricted

   ECParameters ::= CHOICE {
     namedCurve      CURVE.&id({NamedCurve}),
     specifiedCurve  SpecifiedCurve,
     implicitCurve   NULL
   }

   -- Sec 2.1.1.1 Named Curve

   CURVE ::= CLASS { &id OBJECT IDENTIFIER UNIQUE }
     WITH SYNTAX { ID &id }

   NamedCurve CURVE ::= {
    { ID secp192r1 } | { ID sect163k1 } | { ID sect163r2 } |
    { ID secp224r1 } | { ID sect233k1 } | { ID sect233r1 } |
    { ID secp256r1 } | { ID sect283k1 } | { ID sect283r1 } |
    { ID secp384r1 } | { ID sect409k1 } | { ID sect409r1 } |
    { ID secp521r1 } | { ID sect571k1 } | { ID sect571r1 },
    ... -- Extensible
   }

   secp192r1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2)
     curves(3) prime(1) 1 }

   sect163k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 1 }

   sect163r2 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 15 }

   secp224r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 33 }

   sect233k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 26 }

   sect233r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 27 }

   secp256r1 OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) keyType(2)
     curves(3) prime(1) 7 }

   sect283k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 16 }


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   sect283r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 17 }

   secp384r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 34 }

   sect409k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 36 }

   sect409r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 37 }

   secp521r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 35 }

   sect571k1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 38 }

   sect571r1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) certicom(132) curve(0) 39 }

   -- Sec 2.1.1.2 Specified Curve

   SpecifiedCurve ::= SEQUENCE {
     version  SpecifiedCurveVersion
                    ( ecpVer1 | ecpVer2 | ecpVer3 ),
     fieldID  FieldID {{FieldTypes}},
     curve    Curve,            -- Curve E
     base     ECPoint,          -- Base point P
     order    INTEGER,          -- Order n of the base point
     cofactor INTEGER OPTIONAL, -- The integer h = #E(Fq)/n
     hash     HashAlgorithm OPTIONAL,
     ...                        -- Extensible
   }

   SpecifiedCurveVersion ::= INTEGER {
     ecpVer1(1),
     ecpVer2(2),
     ecpVer3(3)
   }

   FIELD-ID ::= TYPE-IDENTIFIER

   FieldID { FIELD-ID:IOSet } ::= SEQUENCE {
     fieldType FIELD-ID.&id({IOSet}),
     parameters FIELD-ID.&Type({IOSet}{@fieldType})
   }


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   FieldTypes FIELD-ID ::= {
     { Prime-p IDENTIFIED BY prime-field } |
     { Characteristic-two IDENTIFIED BY characteristic-two-field },
     ... -- Extensible
   }

   prime-field OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(1) 1 }

   Prime-p ::= INTEGER

   characteristic-two-field OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(1) 2 }

   Characteristic-two ::= SEQUENCE {
     m INTEGER, -- Field size 2^m
     basis CHARACTERISTIC-TWO.&id({BasisTypes}),
     parameters CHARACTERISTIC-TWO.&Type({BasisTypes}{@basis})
   }

   CHARACTERISTIC-TWO ::= TYPE-IDENTIFIER

   BasisTypes CHARACTERISTIC-TWO ::= {
     { NULL        IDENTIFIED BY gnBasis } |
     { Trinomial   IDENTIFIED BY tpBasis } |
     { Pentanomial IDENTIFIED BY ppBasis },
     ...  -- Extensible
   }

   gnBasis OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(2)
     characteristic-two-basis(2) 1 }

   tpBasis OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(2)
     characteristic-two-basis(2) 2 }

   Trinomial ::= INTEGER

   ppBasis OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) ansi-X9-62(10045) fieldType(2)
     characteristic-two-basis(2) 3 }







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   Pentanomial ::= SEQUENCE {
     k1 INTEGER, -- k1 > 0
     k2 INTEGER, -- k2 > k1
     k3 INTEGER  -- k3 > k2
   }

   Curve ::= SEQUENCE {
     a     FieldElement,
     b     FieldElement,
     seed  BIT STRING OPTIONAL
     -- Shall be present if used in SpecifiedCurve
     -- with version of ecdpVer2 or ecdpVer3
   }

   FieldElement ::= OCTET STRING

   ECPoint ::= OCTET STRING

   HashAlgorithm ::= AlgorithmIdentifier {{HashFunctions}}

   HashFunctions ALGORITHM ::= {
     sha1   |
     sha224 |
     sha256 |
     sha384 |
     sha512,
     ... -- Extensible
   }

   sha1 ALGORITHM ::= {
     OID id-sha1 PARMS NULL }

   id-sha1 OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) oiw(14) secsig(3)
     algorithm(2) 26 }

   sha224 ALGORITHM ::= {
     OID id-sha224 PARMS NULL }

   id-sha224 OBJECT IDENTIFIER ::= {
     joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
     csor(3) nistalgorithm(4) hashalgs(2) 4 }







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   sha256 ALGORITHM ::= {
     OID id-sha256 PARMS NULL }

   id-sha256 OBJECT IDENTIFIER ::= {
     joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
     csor(3) nistalgorithm(4) hashalgs(2) 1 }

   sha384 ALGORITHM ::= {
     OID id-sha384 PARMS NULL }

   id-sha384 OBJECT IDENTIFIER ::= {
     joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
     csor(3) nistalgorithm(4) hashalgs(2) 2 }

   sha512 ALGORITHM ::= {
     OID id-sha512 PARMS NULL }

   id-sha512 OBJECT IDENTIFIER ::= {
     joint-iso-itu-t(2) country(16) us(840) organization(1) gov(101)
     csor(3) nistalgorithm(4) hashalgs(2) 3 }

   END



























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Authors' Addresses

   Sean Turner

   IECA, Inc.
   3057 Nutley Street, Suite 106
   Fairfax, VA 22031
   USA

   EMail: turners@ieca.com

   Kelvin Yiu

   Microsoft
   One Microsoft Way
   Redmond, WA 98052-6399
   USA

   Email: kelviny@microsoft.com

   Daniel R. L. Brown

   Certicom Corp
   5520 Explorer Drive #400
   Mississauga, ON L4W 5L1
   CANADA

   EMail: dbrown@certicom.com

   Russ Housley

   Vigil Security, LLC
   918 Spring Knoll Drive
   Herndon, VA 20170
   USA

   EMail: housley@vigilsec.com

   Tim Polk

   NIST
   Building 820, Room 426
   Gaithersburg, MD 20899
   USA

   EMail: wpolk@nist.gov



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Full Copyright Statement

   Copyright (C) The IETF Trust (2008).

   This document is subject to the rights, licenses and restrictions
   contained in BCP 78, and except as set forth therein, the authors
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   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
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Acknowledgment

   Funding for the RFC Editor function is provided by the IETF
   Administrative Support Activity (IASA).





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