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Network Working Group                                        R. Housley
Internet Draft                                           Vigil Security
expires in six months                                        April 2003


                 Using CMS to Protect Firmware Packages

                   <draft-housley-cms-fw-wrap-01.txt>



Status of this Memo

   This document is an Internet-Draft and is in full conformance with
   all provisions of Section 10 of RFC2026.  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
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   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
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   Rim), ftp.ietf.org (US East Coast), or ftp.isi.edu (US West Coast).


Abstract

   This document describes the use of the Cryptographic Message Syntax
   (CMS) to protect firmware packages.  A digital signature is used to
   protect the firmware package from undetected modification and provide
   data origin authentication.  Encryption is optionally used to protect
   the firmware from disclosure, and compression is optionally used to
   reduce the size of the protected firmware package.  A firmware
   package loading signed receipt can optionally be generated to
   acknowledge the successful loading of a firmware package.










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Table of Contents

   Status of this Memo ................................................  1
   Abstract ...........................................................  1
   Table of Contents ..................................................  2
   1   Introduction ...................................................  4
       1.1   Terminology ..............................................  5
       1.2   Architectural Elements ...................................  5
             1.2.1   Hardware Module Requirements .....................  7
             1.2.2   Firmware Package Requirements ....................  7
             1.2.3   Bootstrap Loader Requirements ....................  9
             1.2.4   Cryptographic Algorithm Requirements ............. 11
   2   Firmware Package Protection .................................... 11
       2.1   Firmware Package Protection CMS Content Type Profile ..... 13
             2.1.1   ContentInfo ...................................... 13
             2.1.2   SignedData ....................................... 14
                     2.1.2.1   SignerInfo ............................. 15
                     2.1.2.2   EncapsulatedContentInfo ................ 16
             2.1.3   EncryptedData .................................... 16
                     2.1.3.1   EncryptedContentInfo ................... 16
             2.1.4   CompressedData ................................... 17
                     2.1.4.1   EncapsulatedContentInfo ................ 17
             2.1.5   FirmwarePkgData .................................. 17
       2.2   Signed Attributes ........................................ 18
             2.2.1   Content Type ..................................... 19
             2.2.2   Message Digest ................................... 19
             2.2.3   Firmware Package Identifier ...................... 19
             2.2.4   Target Hardware Module Identifiers ............... 20
             2.2.5   Decrypt Key Identifier ........................... 20
             2.2.6   Implemented Crypto Algorithms .................... 21
             2.2.7   Community Identifiers ............................ 21
             2.2.8   Signing Time ..................................... 22
             2.2.9   Content Hints .................................... 22
             2.2.10  Signing Certificate .............................. 23
       2.3   Unsigned Attributes ...................................... 24
             2.3.1   Wrapped Firmware-Decryption Key .................. 24
   3   Firmware Package Load Receipt .................................. 25
       3.1   Firmware Package Load Receipt CMS Content Type Profile ... 27
             3.1.1   ContentInfo ...................................... 27
             3.1.2   SignedData ....................................... 27
                     3.1.2.1   SignerInfo ............................. 28
                     3.1.2.2   EncapsulatedContentInfo ................ 29
             3.1.3   FirmwarePackageLoadReceipt ....................... 29
       3.2   Signed Attributes ........................................ 30
             3.2.1   Content Type ..................................... 30
             3.2.2   Message Digest ................................... 30
             3.2.3   Signing Time ..................................... 30




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   4   Hardware Module Name ........................................... 31
   5   References ..................................................... 32
       5.1   Normative References ..................................... 32
       5.2   Informative References ................................... 32
   6   Security Considerations ........................................ 33
   7   Author Address ................................................. 34
   Appendix A:  ASN.1 Module .......................................... 35
   Appendix B:  Change History ........................................ 38
   Full Copyright Statement ........................................... 39










































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1  Introduction

   This document describes the use of the Cryptographic Message Syntax
   (CMS) [CMS] to protect firmware packages.  This document also
   describes the use of CMS for firmware package load receipts.  The CMS
   is a data protection encapsulation syntax that makes use of ASN.1
   [X.208-88].  The protected firmware can be associated with any
   particular hardware module; however, this specification was written
   with the requirements of cryptographic hardware modules in mind,
   since such modules have strong security requirements.

   The firmware package contains object code for one or more processors
   that make up the hardware module.  The firmware package, which is
   treated as an opaque binary object, is digitally signed.  Optional
   encryption and compression are also supported.  When all three are
   used, the firmware package is compressed, and then encrypted, and
   then signed.  Compression simply reduces the size of the firmware
   package, allowing more efficient processing and transmission.
   Encryption protects the firmware from disclosure.  The encryption
   algorithm and mode employed may also provide integrity, protecting
   the firmware from undetected modification.  The encryption protects
   proprietary algorithms, classified algorithms, trade secrets, and
   efficient implementation techniques.  The digital signature protects
   the firmware package from undetected modification and provides data
   origin authentication.  The digital signature allows the hardware
   module to confirm that the firmware package comes from an acceptable
   source.

   If encryption is used, the firmware-decryption key must be made
   available to the hardware module via a secure path.  This out-of-band
   key delivery is beyond the scope of this specification.  However, the
   key might be delivered via physical media, delivered via an
   independent electronic path, or embedded in the hardware module at
   the factory by the hardware module vendor.  (This latter approach
   might be appropriate if a security analysis determines that the
   module provides adequate security for an embedded firmware-decryption
   key and a permanent key is acceptable for this application.
   Alternatively, an embedded key-encryption key might be employed to
   facilitate electronic firmware-decryption delivery.)

   Similarly, the signature verification public key must be made
   available to the module in a secure fashion.  CMS provides for
   carriage of certificates, and this facility is used to transfer a
   certificate that contains the signature verification public key (a
   firmware-signing certificate).  However, use of this facility
   introduces one or more level of indirection.  Ultimately, a trust
   anchor public key must be made available to the hardware module.
   Section 1.2 establishes a requirement that the hardware module



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   contain one or more embedded trust anchors.

   Hardware modules may not be capable of accessing certificate
   repositories or delegated path discovery (DPD) servers to acquire
   certificates needed to complete a certification path.  Thus, it is
   the responsibility of the firmware package signer to include
   sufficient certificates to enable each module to validate the
   firmware-signer certificate (see Section 2.1.2).  Similarly, hardware
   modules may not be capable of accessing a CRL repository, an OCSP
   responder, or delegated path validation (DPV) server to acquire
   revocation status information.  Thus, it is the responsibility of the
   entity loading a package into a hardware module to validate the
   firmware-signer certification path prior to loading the package into
   a hardware module.  The means by which this external certificate
   revocation status checking is performed is beyond the scope of this
   specification.

   Hardware modules will only accept firmware packages with a valid
   digital signature and a valid firmware-signer certification path.
   Thus, the trust anchors define the set of entities that can create
   firmware packages for the hardware module.

   After the hardware module successfully validates a firmware package
   for loading, the disposition of the previous firmware package is
   beyond the scope of this specification.  The amount of memory
   available to the hardware module will determine the range of
   alternatives.

   In some cases, hardware modules can generate digitally signed
   receipts to acknowledge the loading of a particular firmware package.
   Such receipts can be used to determine which hardware modules need to
   receive an updated firmware package whenever a flaw in an earlier
   firmware package is discovered.  To generate digitally signed
   receipts, a hardware module is required to have a unique serial
   number, its own private signature key to sign the receipt, and a
   certificate that contains the corresponding signature validation
   public key.

1.1  Terminology

   In this document, the key words MUST, MUST NOT, REQUIRED, SHOULD,
   SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL are to be interpreted as
   described in [STDWORDS].

1.2  Architectural Elements

   The architecture includes the hardware module, the firmware package,
   and a firmware bootstrap loader.  The bootstrap loader MUST have



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   access to one or more trusted public keys, called trust anchors, to
   validate the firmware signer's certificate.  If a firmware loading
   receipt is generated, the bootstrap loader uses the private signature
   key to sign the receipt and includes the signature validation
   certificate to aid receipt validation.  To implement this optional
   capability, the private signature key to sign the receipt and the
   certificate containing the corresponding signature validation public
   key MUST be installed in the hardware module before it is deployed.
   The private key and certificate are usually generated and installed
   as part of the hardware module manufacture process.  Figure 1
   illustrates these architectural elements.


         +------------------------------------------------------+
         |  Hardware Module                                     |
         |                                                      |
         |   +---------------+   +--------------------------+   |
         |   |  Bootstrap    |   |  Firmware Package        |   |
         |   |  Loader       |   |                          |   |
         |   +---------------+   |   +------------------+   |   |
         |                       |   : Firmware Package :   |   |
         |   +---------------+   |   : Identifier and   :   |   |
         |   |  Trust        |   |   : Version Number   :   |   |
         |   |  Anchor(s)    |   |   +------------------+   |   |
         |   +---------------+   |                          |   |
         |                       |   +-------------+        |   |
         |   +---------------+   |   : Algorithm 1 :        |   |
         |   |  Serial Num.  |   |   +-+-----------+-+      |   |
         |   +---------------+   |     : Algorithm 2 :      |   |
         |                       |     +-+-----------+-+    |   |
         |   +---------------+   +       : Algorithm n :    |   |
         |   |  Hardware     |   |       +-------------+    |   |
         |   |  Module Type  |   |                          |   |
         |   +---------------+   +--------------------------+   |
         |                                                      |
         |        +------------------------------------+        |
         |        |  Private Signature Key and         |        |
         |        |  Signature Validation Certificate  |        |
         |        +------------------------------------+        |
         |                                                      |
         +------------------------------------------------------+

                     Figure 1.  Architectural Elements


   Details of managing the trust anchors are outside the scope of this
   specification.  However, the module vendor is REQUIRED to embed one
   or more trust anchors in a module during manufacture.  These trust



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   anchors provide a means of controlling the acceptable sources of
   firmware packages.  The hardware module vendor can include provisions
   for secure, remote management of trust anchors.  One approach is to
   include trust anchors in the firmware packages themselves.  This
   approach is analogous to the optional capability described later for
   updating the bootstrap loader.

   In a cryptographic hardware module, the firmware package might
   implement many different cryptographic algorithms.

   When the firmware package is encrypted, the firmware-decryption key
   and the firmware package MUST both be provided to the hardware
   module.  The firmware-decryption key is authorization to use the
   associated firmware package.  Generally, separate distribution
   mechanisms will be employed for the firmware-decryption key and the
   firmware package.

   ASN.1 object identifiers are used to name the architectural elements.

1.2.1  Hardware Module Requirements

   Many different vendors develop hardware modules, and each vendor
   typically identifies its modules by product type (family) and
   revision level.  A unique object identifier MUST name each hardware
   module type and revision.

   Each hardware module within a family of hardware modules SHOULD have
   a unique serial number.  If present, the bootstrap loader MUST have
   read access to the serial number.  The bootstrap loader uses the
   serial number for authorization decisions (see section 2.2.7) and
   receipt generation (see section 3).

   If the optional receipt generation capability is implemented, then
   the hardware module MUST have a unique serial number, a private
   signature key, and a certificate containing the corresponding public
   signature validation key.

   The hardware module includes one or more processors.  When there are
   multiple processors, one of the processors MUST be responsible for
   bootstrap loader processing.  Once the firmware package is validated,
   the bootstrap loader processor distributes components of the package
   to the appropriate processors within the hardware module.  The
   bootstrap loader is discussed further in section 1.2.3.

1.2.2  Firmware Package Requirements

   Firmware packages are named by a combination of the firmware package
   object identifier and a version number.  A unique object identifier



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   MUST identify the collection of features that characterize the
   firmware package.  For example, firmware packages for a cable modem
   and a wireless LAN network interface card warrant distinct object
   identifiers.  Similarly, firmware packages that implement distinct
   suites of cryptographic algorithms and modes of operation, or which
   emulate different (non-programmable) cryptographic devices warrant
   distinct object identifiers.  The version number MUST identify a
   particular build or release of the firmware package.  The version
   number MUST be a monotonically increasing non-negative integer.
   Generally, an earlier version is replaced with a later one.  In case
   a firmware package with a disastrous flaw is released, subsequent
   firmware package versions MAY designate a stale version number.

   Firmware packages are developed to run on one or more hardware module
   type.  The firmware package digital signature MUST bind the list of
   supported hardware module object identifiers to the firmware package.

   The firmware package MUST contain a certificate path that begins with
   a certificate issued by one of the trust anchors and ends with a
   certificate issued to the firmware signer.  In many cases, the
   firmware package signature will be validated directly with the trust
   anchor public key, avoiding the need to construct certification
   paths.

   The firmware package MAY contain a list of community identifiers.
   These identifiers name the hardware modules that are authorized to
   load the firmware package.  If the firmware package contains a list
   of community identifiers, then the bootstrap loader MUST reject the
   firmware package if the hardware module is not a member of one of the
   identified communities.

   The firmware package MUST contain a complete firmware load for
   hardware module.  That is, the firmware package cannot be a partial
   or incremental set of functions.  This requirement is motivated by a
   desire to minimize complexity and avoid potential security problems.
   From a complexity perspective, if the incremental loading of packages
   were permitted, it would be necessary for each package to identify
   any other packages that are required (its dependencies), and the
   bootstrap loader would have to verify that all of the dependencies
   were satisfied before attempting to execute the firmware.  Two
   security-relevant observations motivate this requirement.  First, if
   the hardware module were based on a general purpose processor or a
   digital signal processor, it would be dangerous to allow such
   packages to be loaded simultaneously unless there is a reference
   monitor to ensure that independent portions of the code cannot
   interfere with one another.  Second, it is difficult evaluate
   arbitrary combinations of software modules [SECREQMTS].




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   When hardware module includes multiple processors, the firmware
   package MUST contain object code for all of the processors.  Internal
   tagging within the firmware package MUST tell the bootstrap loader
   which portion of the overall firmware package is intended for each
   processor; however, this tagging is expected to be specific to each
   hardware module.  Since this specification treats the firmware
   package as an opaque binary object, the format of the firmware
   package is beyond the scope of this specification.

1.2.3  Bootstrap Loader Requirements

   The bootstrap loader can be a permanent part of the hardware module,
   or it can be replaced by a new one contained in a subsequent firmware
   package.  In Figure 1, the bootstrap loader is implemented as
   separate logic within the hardware module.  Not all hardware modules
   will include the ability to replace or update the bootstrap loader,
   and this specification does not mandate such support.  Moreover, this
   specification does not make explicit provisions for separate carriage
   of a replacement bootstrap loader within the firmware package.  The
   firmware package contents are treated as an opaque binary object.

   When the bootstrap loader is part of the firmware package, the
   factory MUST install the first firmware package and the trusted
   anchors in non-volatile memory.  This initial firmware package MUST
   contain the bootstrap loader; it MAY also contain other routines.
   When using separate logic within the hardware module to implement the
   bootstrap loader, two approaches are anticipated.  The bootstrap
   loader can be implemented directly in the hardware, or more likely,
   the bootstrap loader can be implemented by a separate firmware
   package stored in read-only memory or a reserved portion of non-
   volatile memory.  As before, the factory MUST install the bootstrap
   loader and the trust anchors.

   The bootstrap loader requires access to cryptographic routines.
   These routines can be implemented specifically for the bootstrap
   loader, or they can be shared with other hardware module features.
   The bootstrap loader MUST have access to a one-way hash function and
   digital signature verification routines to validate the digital
   signature on the firmware package and to validate the certification
   path for the firmware-signing certificate.

   If firmware packages are encrypted, the bootstrap loader MUST have
   access to a decryption routine.  Access to a corresponding encryption
   function is not required, since hardware modules need not be capable
   of generating firmware packages.  Since some symmetric encryption
   algorithm implementations (like AES), employ separate logic for
   encryption and decryption, some hardware module savings might result.




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   If firmware packages are compressed, the bootstrap loader MUST also
   have access to decompression function.  The decompression function
   can be implemented specifically for the bootstrap loader, or they can
   be shared with other hardware module features.  Access to a
   corresponding compression function is not required, since hardware
   modules need not be capable of generating firmware packages.

   The bootstrap loader requires access to one or more trusted public
   keys, called trust anchors, to validate the certification path of the
   firmware package signer.  The bootstrap loader MUST reject a firmware
   package if it cannot construct a valid certification path from the
   firmware-signing certificate to one of the trust anchors [PROFILE].
   In many cases, the firmware package signature will be validated
   directly with the trust anchor public key, avoiding the need to
   construct certification paths.

   The bootstrap loader MUST reject a firmware package if it cannot
   validate the firmware package digital signature using the public key
   from the firmware-signing certificate.

   The bootstrap loader MUST reject a firmware package if the package's
   list of supported modules does not include the object identifier of
   the hardware module.

   The bootstrap loader MUST reject a firmware package if the firmware
   package includes a list of community identifiers and the hardware
   module is not a member of one of the listed communities.  The means
   of determining community membership is beyond the scope of this
   specification; however, two mechanisms are anticipated, but others
   are possible.  One mechanism uses an attribute certificate signed by
   an appropriate trust anchor to bind the hardware module serial number
   and a community identifier.  Another mechanism explicitly names the
   community members by hardware module serial number.

   The bootstrap loader MUST reject a firmware package if it cannot
   successfully decrypt the firmware package using the firmware-
   decryption key available to the hardware module.  The firmware
   package contains an identifier of the firmware-decryption key needed
   for decryption.

   When an earlier version of a firmware package is replacing a later
   one, the bootstrap loader SHOULD generate a warning.  In case a
   firmware package with a disastrous flaw is released and subsequent
   firmware package versions designate a stale version number, the
   bootstrap loader SHOULD prevent loading of the stale version and
   versions earlier than the stale version.





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1.2.4  Cryptographic Algorithm Requirements

   Firmware for cryptographic hardware modules will include
   cryptographic algorithm implementations; however, firmware for other
   types of hardware modules MAY include cryptographic algorithm
   implementations for the validation firmware packages.

   A unique algorithm object identifier MUST be assigned for each
   algorithm and mode implemented by a firmware package.  The algorithm
   object identifiers can be used to determine whether a particular
   firmware package satisfies the needs of a particular application.  To
   facilitate the development of algorithm agile applications, the
   cryptographic module interface SHOULD allow applications to query the
   cryptographic module for the object identifiers associated with each
   cryptographic algorithm contained in the currently loaded firmware
   package.  Applications SHOULD also be able to query the cryptographic
   module to determine attributes associated with each algorithm.  Such
   attributes might include the algorithm type (symmetric encryption,
   asymmetric encryption, key agreement, one-way hash function, digital
   signature, and so on), the algorithm block size or modulus size, and
   parameters for asymmetric algorithms.  This specification does not
   establish the encoding conventions for these attributes.

2  Firmware Package Protection

   The Cryptographic Message Syntax (CMS) is used to protect firmware,
   which is treated as an opaque binary object.  A digital signature is
   used to protect the firmware package from undetected modification and
   provide data origin authentication.  Encryption is optionally used to
   protect the firmware from disclosure, and compression is optionally
   used to reduce the size of the protected firmware package.  The CMS
   ContentInfo content type MUST always be present, and it MUST
   encapsulate the CMS SignedData content type.  If the firmware package
   is encrypted, then the CMS SignedData content type MUST encapsulate
   the CMS EncryptedData content type.  If the firmware package is
   compressed, then either the CMS SignedData content type (when
   encryption is not used) or the CMS EncryptedData content type (when
   encryption is used) MUST encapsulate the CMS CompressedData content
   type.  Finally, either the CMS SignedData content type (when neither
   encryption nor compression is used) or the CMS EncryptedData content
   type (when encryption is used, but compression is not used) or CMS
   CompressedData content type (when compression is used) MUST
   encapsulate the simple firmware package using the FirmwarePkgData
   content type defined in this specification (see section 2.1.5).







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   The firmware protection is summarized by:

      ContentInfo {
        contentType          id-signedData, -- (1.2.840.113549.1.7.2)
        content              SignedData
      }

      SignedData {
        version              CMSVersion,
        digestAlgorithms     DigestAlgorithmIdentifiers,
        encapContentInfo     EncapsulatedContentInfo,
        certificates         CertificateSet, -- Signer certification path
        crls                 CertificateRevocationLists, -- Omit
        signerInfos          SET OF SignerInfo -- Only one
      }

      SignerInfo {
        version              CMSVersion,
        sid                  SignerIdentifier,
        digestAlgorithm      DigestAlgorithmIdentifier,
        signedAttrs          SignedAttributes, -- Required
        signatureAlgorithm   SignatureAlgorithmIdentifier,
        signature            SignatureValue,
        unsignedAttrs        UnsignedAttributes -- Optional
      }

      EncapsulatedContentInfo {
        eContentType         id-encryptedData, -- (1.2.840.113549.1.7.6)
                             -- OR --
                             id-ct-compressedData,
                                       -- (1.2.840.113549.1.9.16.1.9)
                             -- OR --
                             id-ct-firmwarePackage,
                                       -- (1.2.840.113549.1.9.16.1.16)
        eContent             OCTET STRING
                                       -- Contains EncryptedData OR
                                       -- CompressedData OR FirmwarePkgData
      }

      EncryptedData {
        version              CMSVersion,
        encryptedContentInfo EncryptedContentInfo,
        unprotectedAttrs     UnprotectedAttributes  -- Omit
      }







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      EncryptedContentInfo {
        contentType          id-ct-compressedData,
                                       -- (1.2.840.113549.1.9.16.1.9)
                             -- OR --
                             id-ct-firmwarePackage,
                                       -- (1.2.840.113549.1.9.16.1.16)
        contentEncryptionAlgorithm ContentEncryptionAlgorithmIdentifier,
        encryptedContent     OCTET STRING
                                       -- Contains CompressedData OR
                                       -- FirmwarePkgData
      }

      CompressedData {
        version              CMSVersion,
        compressionAlgorithm CompressionAlgorithmIdentifier,
        encapContentInfo     EncapsulatedContentInfo
      }

      EncapsulatedContentInfo {
        eContentType         id-ct-firmwarePackage,
                                          -- (1.2.840.113549.1.9.16.1.16)
        eContent             OCTET STRING -- Contains FirmwarePkgData
      }

      FirmwarePkgData        OCTET STRING -- Contains the firmware

2.1  Firmware Package Protection CMS Content Type Profile

   This section specifies the conventions for using the CMS ContentInfo,
   SignedData, EncryptedData, and CompressedData content types.  It also
   defines the FirmwarePkgData content type.

2.1.1  ContentInfo

   The CMS requires the outer most encapsulation to be ContentInfo
   [CMS].  The fields of ContentInfo are used as follows:

      contentType indicates the type of the associated content, and in
      this case, the encapsulated type is always SignedData.  The id-
      signedData (1.2.840.113549.1.7.2) object identifier MUST be
      present in this field.

      content holds the associated content, and in this case, the
      encapsulated SignedData MUST be present in this field.







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2.1.2  SignedData

   The SignedData content type [CMS] contains the signed firmware
   package (which might be encrypted or compressed prior to signature),
   the certificates needed to validate the signature, and one digital
   signature value.  The fields of SignedData are used as follows:

      version is the syntax version number, and in this case, is MUST be
      set to 3.

      digestAlgorithms is a collection of message digest algorithm
      identifiers, and in this case, it MUST contain a single message
      digest algorithm identifier.  The message digest algorithm
      employed by the firmware signer MUST be present.

      encapContentInfo is the signed content, consisting of a content
      type identifier and the content itself.  The use of the
      EncapsulatedContentInfo type is discussed further in section
      2.1.2.2.

      certificates is an optional collection of certificates.  If the
      trust anchor directly signed the firmware package, then
      certificates is omitted.  If the trust anchor signed a
      certificate, then certificates MUST include the X.509 certificate
      of the firmware signer.  The set of certificates MUST be
      sufficient for the bootstrap loader to construct a certification
      path from the trust anchor to the firmware signer's certificate.
      PKCS#6 extended certificates [PKCS#6] and attribute certificates
      (either version 1 or version 2) [X.509-97, X.509-00, ACPROFILE]
      MUST NOT be included in the set of certificates.

      crls is an optional collection of certificate revocation lists
      (CRLs), and in this case, CRLs MUST NOT be included.  It is
      anticipated that firmware packages may be generated, signed, and
      made available in repositories for downloading into hardware
      modules.  In such contexts, it would be difficult to include
      timely CRLs in the firmware package.

      signerInfos is a collection of per-signer information, and in this
      case, the collection MUST contain exactly one SignerInfo.  The use
      of the SignerInfo type is discussed further in section 2.1.2.1.










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2.1.2.1  SignerInfo

   The firmware signer is represented in the SignerInfo type.  The
   fields of SignerInfo are used as follows:

      version is the syntax version number, and it MUST be either 1 or
      3, depending on the method used to identify the firmware signer's
      public key.  The use of the subjectKeyIdentifier (resulting in a
      version of 3) is RECOMMENDED.

      sid specifies the signer's certificate (and thereby the signer's
      public key).  Two alternatives are supported, and the bootstrap
      loader MUST support both alternatives.  The issuerAndSerialNumber
      alternative identifies the signer's certificate by the issuer's
      distinguished name and the certificate serial number; the
      subjectKeyIdentifier alternative identifies the signer's
      certificate by the X.509 subjectKeyIdentifier extension value.
      The use of the subjectKeyIdentifier by firmware signers is
      RECOMMENDED.

      digestAlgorithm identifies the message digest algorithm, and any
      associated parameters, used by the firmware signer.  It MUST
      contain the message digest algorithms employed by the signer of
      the encrypted firmware package.  (Note that this message digest
      algorithm identifier MUST be the same as the one carried in the
      digestAlgorithms value in SignedData.)

      signedAttrs is a collection of attributes that are signed along
      with the firmware package.  The signedAttrs are optional in the
      CMS, but in this specification, signedAttrs are REQUIRED.  The SET
      OF attributes MUST be DER encoded [X.509-88].  Section 2.2 of this
      document lists the attributes that MUST be included in the
      collection; other attributes MAY be included as well.

      signatureAlgorithm identifies the signature algorithm, and any
      associated parameters, used by the firmware signer to generate the
      digital signature.

      signature is the digital signature value.

      unsignedAttrs is an optional collection of attributes that are not
      signed.  Section 2.3 of this document lists the attributes that
      MAY be included in the collection.








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2.1.2.2  EncapsulatedContentInfo

   The EncryptedData content type encapsulates the encrypted firmware
   package, and it is carried within the EncapsulatedContentInfo type.
   The fields of EncapsulatedContentInfo are used as follows:

      eContentType is an object identifier that uniquely specifies the
      content type, and in this case, the value MUST be either id-
      encryptedData (1.2.840.113549.1.7.6), id-ct-compressedData
      (1.2.840.113549.1.9.16.1.9), or id-ct-firmwarePackage
      (1.2.840.113549.1.9.16.1.16).  When it contains id-encryptedData,
      then the firmware packages was encrypted prior to signing.  When
      it contains id-ct-compressedData, then the firmware package was
      compressed prior to signing, but the firmware package was not
      encrypted.  When it contains id-ct-firmwarePackage, then the
      firmware package was not compressed or encrypted prior to signing.

      eContent is the encrypted firmware, encoded as an octet string.
      The eContent octet string need not be DER encoded.

2.1.3  EncryptedData

   The EncryptedData content type [CMS] contains the encrypted firmware
   package (which might be compressed prior to encryption). The fields
   of EncryptedData are used as follows:

      version is the syntax version number, and in this case, version
      MUST be 0.

      encryptedContentInfo is the encrypted content information.  The
      use of the EncryptedContentInfo type is discussed further in
      section 2.1.3.1.


      unprotectedAttrs is an optional collection of unencrypted
      attributes, and in this case, unprotectedAttrs MUST NOT be
      present.

2.1.3.1  EncryptedContentInfo

   The encrypted firmware package is encapsulated in the
   EncryptedContentInfo type.  The fields of EncryptedContentInfo are
   used as follows:

      contentType indicates the type of content, and in this case, it
      MUST contain either id-ct-compressedData
      (1.2.840.113549.1.9.16.1.9) or id-ct-firmwarePackage
      (1.2.840.113549.1.9.16.1.16).  When it contains id-ct-



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      compressedData, then the firmware package was compressed prior to
      encryption.  When it contains id-ct-firmwarePackage, then the
      firmware package was not compressed prior to encryption.

      contentEncryptionAlgorithm identifies the firmware-encryption
      algorithm, and any associated parameters, used to encrypt the
      firmware package.

      encryptedContent is the result of encrypting the firmware package.
      The field is optional; however, in this case, it MUST be present.

2.1.4  CompressedData

   The CompressedData content type [COMPRESS] contains the compressed
   firmware package.  If the firmware package was not compressed, then
   the CompressedData content type is not present.  The fields of
   CompressedData are used as follows:

      version is the syntax version number; in this case, it MUST be 0.

      compressionAlgorithm identifies the compression algorithm, and any
      associated parameters, used to compress the firmware package.

      encapContentInfo is the compressed content, consisting of a
      content type identifier and the content itself.  The use of the
      EncapsulatedContentInfo type is discussed further in section
      2.1.4.1.

2.1.4.1  EncapsulatedContentInfo

   The CompressedData content type encapsulates the compressed firmware
   package, and it carried within the EncapsulatedContentInfo type.  The
   fields of EncapsulatedContentInfo are used as follows:

      eContentType is an object identifier that uniquely specifies the
      content type, and in this case, it MUST be the value of id-ct-
      firmwarePackage (1.2.840.113549.1.9.16.1.16).

      eContent is the compressed firmware, encoded as an octet string.
      The eContent octet string need not be DER encoded.

2.1.5  FirmwarePkgData

   The FirmwarePkgData content type contains the firmware package.  It
   is a straightforward encapsulation in an octet string, and it need
   not be DER encoded.





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   The FirmwarePkgData content type is identified by the id-ct-
   firmwarePackage object identifier:

      id-ct-firmwarePackage OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) ct(1) 16 }

   The FirmwarePkgData content type is a simple octet string:

      FirmwarePkgData ::= OCTET STRING

2.2  Signed Attributes

   The firmware signer MUST digitally sign a collection of attributes
   along with the firmware package.  Each attribute in the collection
   MUST be DER encoded [X.509-88].  The syntax for attributes is defined
   in [CMS], but it is repeated here for convenience:

      Attribute ::= SEQUENCE {
        attrType OBJECT IDENTIFIER,
        attrValues SET OF AttributeValue }

      AttributeValue ::= ANY

   Each of the attributes used with this profile has a single attribute
   value, even though the syntax is defined as a SET OF AttributeValue.
   There MUST be exactly one instance of AttributeValue present.

   The SignedAttributes syntax within signerInfo is defined as a SET OF
   Attributes.  The SignedAttributes MUST include only one instance of
   any particular attribute.

   The firmware signer MUST include the following four attributes:
   content-type, message-digest, firmware-package-identifier, and
   target-hardware-module-identifiers.

   If the firmware package is encrypted, then the firmware signer MUST
   also include the decrypt-key-identifier attribute.

   If the firmware package implements cryptographic algorithms, then the
   firmware signer MUST also include the implemented-crypto-algorithms
   attribute.

   If the firmware package is intended for use only by specific
   communities, then the firmware signer MUST also include the
   community-identifiers attribute.

   The firmware signer SHOULD also include the three following



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   attributes: signing-time, content-hints, and signing-certificate.

   The firmware signer MAY include any other attribute that it deems
   appropriate.

2.2.1  Content Type

   The firmware signer MUST include a content-type attribute with the
   value of id-encryptedData (1.2.840.113549.1.7.6), id-ct-
   compressedData (1.2.840.113549.1.9.16.1.9), or id-ct-firmwarePackage
   (1.2.840.113549.1.9.16.1.16).  When it contains id-encryptedData,
   then the firmware packages was encrypted prior to signing.  When it
   contains id-ct-compressedData, then the firmware package was
   compressed prior to signing, but the firmware package was not
   encrypted.  When it contains id-ct-firmwarePackage, then the firmware
   package was not compressed or encrypted prior to signing.  Section
   11.1 of [CMS] defines the content-type attribute.

2.2.2  Message Digest

   The firmware signer MUST include a message-digest attribute, having
   as its value the message digest of the signed firmware package (which
   might be encrypted or compressed prior to signing).  Section 11.2 of
   [CMS] defines the message-digest attribute.

2.2.3  Firmware Package Identifier

   The firmware-package-identifier attribute type names the protected
   firmware package with an object identifier and a version number.  The
   object identifier names a collection of functions implemented by the
   firmware package, and the version number is a non-negative integer
   that identifies a particular build or release of the firmware
   package.

   In case a firmware package with a disastrous flaw is released, the
   firmware package MAY designate a stale version number.  The hardware
   module bootstrap loader SHOULD prevent subsequent rollback to the
   stale version or versions earlier than the stale version.

   The following object identifier identifies the firmware-package-
   identifier attribute:

      id-aa-firmwarePackageID OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) aa(2) 35 }






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   The firmware-package-identifier attribute values have ASN.1 type
   FirmwarePackageIdentifier:

      FirmwarePackageIdentifier ::= SEQUENCE {
        fwPkgID OBJECT IDENTIFIER,
        verNum INTEGER (0..MAX),
        staleVerNum INTEGER (0..MAX) OPTIONAL }

2.2.4  Target Hardware Module Identifiers

   The target-hardware-module-identifiers attribute type names the types
   of hardware modules that the firmware package supports.  A unique
   object identifier names each supported hardware model and revision.

   The following object identifier identifies the target-hardware-
   module-identifiers attribute:

      id-aa-targetHardwareIDs OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) aa(2) 36 }

   The target-hardware-module-identifiers attribute values have ASN.1
   type TargetHardwareIdentifiers:

      TargetHardwareIdentifiers ::= SEQUENCE OF OBJECT IDENTIFIER

2.2.5  Decrypt Key Identifier

   The decrypt-key-identifier attribute type names the symmetric key
   needed to decrypt the encapsulated firmware package.  No particular
   structure is imposed on the key identifier.  The means by which the
   firmware-decryption key is securely distributed to all modules that
   are authorized to use the associated firmware package is beyond the
   scope of this specification.

   The following object identifier identifies the decrypt-key-identifier
   attribute:

      id-aa-decryptKeyID OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) aa(2) 37 }

   The decrypt-key-identifier attribute values have ASN.1 type
   DecryptKeyIdentifier:

      DecryptKeyIdentifier ::= OCTET STRING





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2.2.6  Implemented Crypto Algorithms

   The implemented-crypto-algorithms attribute type names the
   cryptographic algorithms that are implemented by the firmware package
   and available to applications.  Only those algorithms that are made
   available at the interface of the cryptographic module are to be
   listed.  Any cryptographic algorithm that is used internally and not
   accessible via the cryptographic module interface MUST NOT be listed.
   For example, if the firmware package implements the decryption
   algorithm for future firmware installations and this algorithm is not
   made available outside the cryptographic module, then the firmware-
   decryption algorithm would not be listed.

   The object identifier portion of its AlgorithmIdentifier identifies
   each algorithm.

   The following object identifier identifies the implemented-crypto-
   algorithms attribute:

      id-aa-implCryptoAlgs OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) aa(2) 38 }

   The implemented-crypto-algorithms attribute values have ASN.1 type
   ImplementedCryptoAlgorithms:

      ImplementedCryptoAlgorithms ::= SEQUENCE OF OBJECT IDENTIFIER

2.2.7  Community Identifiers

   The community-identifiers attribute type names the communities that
   are permitted to load the firmware package.  The bootstrap loader
   MUST reject the firmware package if the hardware module is not a
   member of one of the identified communities.  The means of
   determining community membership is beyond the scope of this
   specification.  Two mechanisms are anticipated, but others are
   possible.  One mechanism uses an attribute certificate signed by an
   appropriate trust anchor to bind the hardware module serial number
   and a community identifier.  In this case, an object identifier names
   the community.  Another mechanism explicitly names the community
   members by hardware module serial number.

   The community-identifiers attribute type names the authorized
   communities by a list of object identifiers, by a list of hardware
   module identifiers, or by a combination of the two.  A hardware
   module identifier is an object identifier that names the hardware
   module type and a serial number.  To facilitate compact
   representation of serial numbers, a contiguous block can be specified



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   by the lowest authorized serial number and the highest authorized
   serial number.

   The following object identifier identifies the community-identifiers
   attribute:

      id-aa-communityIdentifiers OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) aa(2) 40 }

   The community-identifiers attribute values have ASN.1 type
   CommunityIdentifiers:

      CommunityIdentifiers ::= SEQUENCE OF CommunityIdentifier

      CommunityIdentifier ::= CHOICE {
        communityOID OBJECT IDENTIFIER,
        hwModuleList HardwareModules }

      HardwareModules ::= SEQUENCE {
        hwType OBJECT IDENTIFIER,
        hwSerialEntries SEQUENCE OF HardwareSerialEntry }

      HardwareSerialEntry ::= CHOICE {
        single OCTET STRING,
        block SEQUENCE {
          low OCTET STRING,
          high OCTET STRING } }

2.2.8  Signing Time

   The firmware signer SHOULD include a signing-time attribute,
   specifying the time at which the signature was applied to the
   encrypted firmware.  Section 11.3 of [CMS] defines the signing-time
   attribute.

2.2.9  Content Hints

   The firmware signer SHOULD include a content-hints attribute,
   including a brief text description of the firmware package.  The text
   is encoded in UTF-8, which supports most of the world's writing
   systems [UTF-8].  Section 2.9 of [ESS] defines the content-hints
   attribute.








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   The content-hints attribute contains two fields, and in this case,
   both fields MUST be present.  The fields of ContentHints are used as
   follows:

      contentDescription provides a brief text description of the
      firmware package.

      contentType provides the content type of the inner most content
      type, and in this case, it MUST be id-ct-firmwarePackage
      (1.2.840.113549.1.9.16.1.16).

2.2.10  Signing Certificate

   The firmware signer SHOULD include a signing-certificate attribute,
   identifying the certificate the used by the firmware signer.  Section
   5.4 of [ESS] defines the signing-certificate attribute.

   The signing-certificate attribute contains two fields: certs and
   policies.  The certs field MUST be present, and the policies field
   MAY be present.  The fields of SigningCertificate are used as
   follows:

      certs contains a sequence certificate identifiers.  In this case,
      sequence of certificate identifiers contains a single entry.  The
      certs field MUST contain only the certificate identifier of the
      certificate that contains the public key used to verify the
      firmware signature.  The certs field uses the ESSCertID syntax
      specified in section 5.4 of [ESS], and it is comprised of the
      SHA-1 hash [SHA1] of the entire ASN.1 DER encoded certificate and,
      optionally, the certificate issuer and the certificate serial
      number.  The SHA-1 hash value MUST be present.  The certificate
      issuer and the certificate serial number SHOULD be present.

      policies is optional, and when it is present, it contains a
      sequence policy information.  In this case, the sequence of policy
      information contains a single entry.  The policies field, when
      present, MUST contain only one entry, and that entry MUST match
      one of the certificate policies in the certificate policies
      extension of the certificate that contains the public key used to
      verify the firmware signature.  The policies field uses the
      PolicyInformation syntax specified in section 4.2.1.5 of
      [PROFILE], and it is comprised of the certificate policy object
      identifier and, optionally, certificate policy qualifiers.  The
      certificate policy object identifier MUST be present.  The
      certificate policy qualifiers SHOULD NOT be present.






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2.3  Unsigned Attributes

   A collection of unsigned attributes MAY be included.  Since the
   digital signature does not cover these attributes, they can be
   altered at any point in the delivery path from the firmware signer to
   the hardware module.  This property can be employed to distribute the
   firmware-decryption key along with the encrypted and signed firmware
   package, allowing the firmware-decryption key to be wrapped with a
   different key-encryption key for each link in the distribution chain.
   The syntax for attributes is defined in [CMS], and it is repeated at
   the beginning of section 2.2 of this document for convenience.

   Each of the attributes used with this profile has a single attribute
   value, even though the syntax is defined as a SET OF AttributeValue.
   There MUST NOT be zero nor more than one instances of AttributeValue
   present.

   The UnsignedAttributes syntax within signerInfo is defined as a SET
   OF Attributes.  The UnsignedAttributes MUST include only one instance
   of any particular attribute.

   The signed firmware package MAY include the wrapped-firmware-
   decryption-key attribute.  The signed firmware package MUST NOT
   include any unsigned attributes other than the wrapped-firmware-
   decryption-key attribute.

2.3.1  Wrapped Firmware Decryption Key

   The firmware signer, or any other party in the distribution chain,
   MAY include a wrapped-firmware-decryption-key attribute.

   The following object identifier identifies the wrapped-firmware-
   decryption-key attribute:

      id-aa-wrappedFirmwareKey OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) aa(2) 39 }

   The wrapped-firmware-decryption-key attribute values have ASN.1 type
   of EnvelopedData.  Section 6 of [CMS] defines the EnvelopedData
   content type, which is used to construct the value of the attribute.
   The EnvelopedData does not include an encrypted content, as the key
   normally used to decrypt the encapsulated content is the firmware-
   decryption key.  Section 6 of [CMS] refers to this key as the
   content-encryption key.

   The EnvelopedData syntax support many different key management
   algorithms.  Four general techniques are supported: key transport,



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   key agreement, symmetric key-encryption keys, and passwords.

   The EnvelopedData content type is profiled for the wrapped-firmware-
   decryption-key attribute.  The EnvelopedData fields are described
   fully in Section 6 of [CMS].  Additional rules apply when
   EnvelopedData is used as a wrapped-firmware-decryption-key attribute.

   Within the EnvelopedData structure:

      - The set of certificates included in OriginatorInfo MUST NOT
        include certificates with a type of extendedCertificate or
        v1AttrCert.

      - The optional unprotectedAttrs field MUST NOT be present.

   Within the EncryptedContentInfo structure:

      - contentType MUST contain id-data (1.2.840.113549.1.7.1).

      - contentEncryptionAlgorithm identifies the firmware-encryption
        algorithm, and any associated parameters, used to encrypt the
        firmware package.

      - encryptedContent is optional, and in this case, it MUST NOT
        be present.

3  Firmware Package Load Receipt

   The Cryptographic Message Syntax (CMS) is be used to sign a firmware
   package load receipt.  Support for firmware package load receipts is
   OPTIONAL.  However, those hardware modules that choose to generate
   such receipts MUST follow the conventions specified in this section.

   Hardware modules that support receipt generation MUST have a unique
   serial number, a private signature key to sign the receipt, and a
   corresponding signature validation certificate to include in the
   receipt to aid validation.

   The firmware package load receipt is encapsulated by SignedData,
   which is in turn encapsulated by ContentInfo.











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   The firmware package load receipt protection is summarized by:

      ContentInfo {
        contentType          id-signedData, -- (1.2.840.113549.1.7.2)
        content              SignedData
      }

      SignedData {
        version              CMSVersion,
        digestAlgorithms     DigestAlgorithmIdentifiers,
        encapContentInfo     EncapsulatedContentInfo,
        certificates         CertificateSet, -- Module certificate
        crls                 CertificateRevocationLists, -- Omit
        signerInfos          SET OF SignerInfo -- Only one
      }

      SignerInfo {
        version              CMSVersion,
        sid                  SignerIdentifier,
        digestAlgorithm      DigestAlgorithmIdentifier,
        signedAttrs          SignedAttributes, -- Required
        signatureAlgorithm   SignatureAlgorithmIdentifier,
        signature            SignatureValue,
        unsignedAttrs        UnsignedAttributes -- Omit
      }

      EncapsulatedContentInfo {
        eContentType         id-ct-firmwareLoadReceipt,
                                  -- (1.2.840.113549.1.9.16.1.17)
        eContent             OCTET STRING -- Contains receipt
      }

      FirmwarePackageLoadReceipt {
        hwType                OBJECT IDENTIFIER, -- Hardware module type
        hwSerialNum           OCTET STRING, -- H/W module serial number
        fwPkgID               OBJECT IDENTIFIER, -- Package identifier


        verNum                INTEGER, -- Release or build number
        decryptKeyID          OCTET STRING -- Optional
      }










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3.1  Firmware Package Load Receipt CMS Content Type Profile

   This section specifies the conventions for using the CMS ContentInfo
   and SignedData content types for firmware package load receipts.  It
   also defines the firmware package load receipt content type.

3.1.1  ContentInfo

   The CMS requires the outer most encapsulation to be ContentInfo
   [CMS].  The fields of ContentInfo are used as follows:

      contentType indicates the type of the associated content, and in
      this case, the encapsulated type is always SignedData.  The id-
      signedData (1.2.840.113549.1.7.2) object identifier MUST be
      present in this field.

      content holds the associated content, and in this case, the
      encapsulated SignedData MUST be present in this field.

3.1.2  SignedData

   The SignedData content type consists the firmware package load
   receipt, the hardware module certificate, and one digital signature.
   The fields of SignedData are used as follows:

      version is the syntax version number, and in this case, is MUST be
      set to 3.

      digestAlgorithms is a collection of message digest algorithm
      identifiers, and in this case, it MUST contain a single message
      digest algorithm identifier.  The message digest algorithms
      employed by the hardware module MUST be present.

      encapContentInfo is the signed content, consisting of a content
      type identifier and the content itself.  The use of the
      EncapsulatedContentInfo type is discussed further in section
      3.1.2.2.

      certificates is an optional collection of certificates, and in
      this case, it MUST include the X.509 certificate of the hardware
      module.  PKCS#6 extended certificates [PKCS#6] and attribute
      certificates (either version 1 or version 2) [X.509-97, X.509-00,
      ACPROFILE] MUST NOT be included in the set of certificates.

      crls is an optional collection of certificate revocation lists
      (CRLs), and in this case, CRLs MUST NOT be included.  (Hardware
      modules will probably not have the ability to obtain the most
      recent CRLs for inclusion.)



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      signerInfos is a collection of per-signer information, and in this
      case, the collection MUST contain exactly one SignerInfo.  The use
      of the SignerInfo type is discussed further in section 3.1.2.1.

3.1.2.1  SignerInfo

   The hardware module is represented in the SignerInfo type.  The
   fields of SignerInfo are used as follows:

      version is the syntax version number, and it MUST be either 1 or
      3, depending on the method used to identify the hardware module's
      public key.  The use of the subjectKeyIdentifier (resulting in a
      version of 3) is RECOMMENDED.

      sid specifies the hardware module's certificate (and thereby the
      hardware module's public key).  There are two alternatives, but
      the hardware module MUST support only one of the alternatives.
      The issuerAndSerialNumber alternative identifies the hardware
      module's certificate by the issuer's distinguished name and the
      certificate serial number; the subjectKeyIdentifier alternative
      identifies the hardware module's certificate by the X.509
      subjectKeyIdentifier extension value.  The use of the
      subjectKeyIdentifier by hardware modules is RECOMMENDED.

      digestAlgorithm identifies the message digest algorithm, and any
      associated parameters, used by the hardware module.  It MUST
      contain the message digest algorithms employed to sign the
      receipt.  (Note that this message digest algorithm identifier MUST
      be the same as the one carried in the digestAlgorithms value in
      SignedData.)

      signedAttrs is a collection of attributes that are signed along
      with the firmware package load receipt.  The signedAttrs are
      optional in the CMS, but in this specification, signedAttrs are
      REQUIRED.  The SET OF attributes MUST be DER encoded [X.509-88].
      Section 3.2 of this document lists the attributes that MUST be
      included in the collection.

      signatureAlgorithm identifies the signature algorithm, and any
      associated parameters, used by to sign the receipt.

      signature is the digital signature.

      unsignedAttrs is an optional collection of attributes that are not
      signed, and in this case, there MUST NOT be any unsigned
      attributes present.





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3.1.2.2  EncapsulatedContentInfo

   The FirmwarePackageLoadReceipt is encapsulated in an OCTET STRING,
   and it is carried within the EncapsulatedContentInfo type.  The
   fields of EncapsulatedContentInfo are used as follows:

      eContentType is an object identifier that uniquely specifies the
      content type, and in this case, it MUST be the value of id-ct-
      firmwareLoadReceipt (1.2.840.113549.1.9.16.1.17).

      eContent is the firmware package load receipt, encapsulated in an
      OCTET STRING.  The eContent octet string need not be DER encoded.

3.1.3  FirmwarePackageLoadReceipt

   The following object identifier identifies the firmware package load
   receipt content type:

      id-ct-firmwareLoadReceipt OBJECT IDENTIFIER ::= {
        iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
        smime(16) ct(1) 17 }

   The firmware package load receipt content type has the ASN.1 type
   FirmwarePackageLoadReceipt:

      FirmwarePackageLoadReceipt ::= SEQUENCE {
        hwType OBJECT IDENTIFIER,
        hwSerialNum OCTET STRING,
        fwPkgID OBJECT IDENTIFIER,
        verNum INTEGER (0..MAX),
        decryptKeyID OCTET STRING OPTIONAL }

   The fields of the FirmwarePackageLoadReceipt type have the following
   meanings:

      hwType is an object identifier that identifies the type of
      hardware module on which the firmware package was loaded.

      hwSerialNum is the serial number of the hardware module on which
      the firmware package was loaded.  No particular structure is
      imposed on the serial number; it need not be an integer.  However,
      the combination of the hwType and hwSerialNum uniquely identifies
      the hardware module.

      fwPkgID identifies the type of firmware package that was loaded.

      verNum identifies the version of firmware package that was loaded.
      The combination of the fwPkgID and verNum specify a particular



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      firmware package.  The version number is a non-negative integer
      that identifies a particular build or release of the firmware
      package.

      decryptKeyID is optional, and when it is present it identifies the
      firmware-decryption key that was used to decrypt the firmware
      package.

3.2  Signed Attributes

   The hardware module MUST digitally sign a collection of attributes
   along with the firmware package load receipt.  Each attribute in the
   collection in MUST be DER encoded [X.509-88].  The syntax for
   attributes is defined in [CMS], and it was repeated in section 2.2
   for convenience.

   Each of the attributes used with this profile has a single attribute
   value, even though the syntax is defined as a SET OF AttributeValue.
   There MUST be exactly one instance of AttributeValue present.

   The SignedAttributes syntax within signerInfo is defined as a SET OF
   Attributes.  The SignedAttributes MUST include only one instance of
   any particular attribute.

   The hardware module MUST include the content-type and message-digest
   attributes.  If the hardware module includes a real-time clock, then
   the hardware module SHOULD also include the signing-time attribute.
   The hardware module MAY include any other attribute that it deems
   appropriate.

3.2.1  Content Type

   The hardware module MUST include a content-type attribute with the
   value of id-ct-firmwareLoadReceipt (1.2.840.113549.1.9.16.1.17).
   Section 11.1 of [CMS] defines the content-type attribute.

3.2.2  Message Digest

   The hardware module MUST include a message-digest attribute, having
   as its value the message digest of the FirmwarePackageLoadReceipt
   content.  Section 11.2 of [CMS] defines the message-digest attribute.

3.2.3  Signing Time

   If the hardware module includes a real-time clock, then hardware
   module SHOULD include a signing-time attribute, specifying the time
   at which the receipt was generated.  Section 11.3 of [CMS] defines
   the signing-time attribute.



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4  Hardware Module Name

   Support for firmware package load receipts, as discussed in section
   3, is OPTIONAL.  Hardware modules that support receipt generation
   MUST have a unique serial number, a private signature key to sign the
   receipt, and a corresponding signature validation certificate
   [PROFILE] to include in the receipt to aid validation.  The
   conventions for hardware module naming in the signature validation
   certificates are specified in this section.

   The hardware module vendor issues the signature validation
   certificate.  It is expected that this will be done at the time of
   manufacture.  The subject name in this certificate identifies the
   hardware module.  The subject distinguished name is empty, but a
   critical subject alternative name extension contains the hardware
   module name.  The otherName choice within the GeneralName structure
   is used.

   The hardware module name form is identified by the id-on-
   hardwareModuleName object identifier:

      id-on-hardwareModuleName OBJECT IDENTIFIER ::= {
        iso(1) identified-organization(3) dod(6) internet(1) security(5)
        mechanisms(5) pkix(7) on(8) 4 }

   A HardwareModuleName is composed of an object identifier and an octet
   string:

      HardwareModuleName ::= SEQUENCE {
        hwType OBJECT IDENTIFIER,
        hwSerialNum OCTET STRING }

   The fields of the HardwareModuleName type have the following
   meanings:

      hwType is an object identifier that identifies the type of
      hardware module.

      hwSerialNum is the serial number of the hardware module.  No
      particular structure is imposed on the serial number; it need not
      be an integer.  However, the combination of the hwType and
      hwSerialNum uniquely identifies the hardware module.









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5  References

   This section provides normative and informative references.

5.1  Normative References

   COMPRESS   Gutmann, P.  Compressed Data Content Type for
              Cryptographic Message Syntax (CMS).  RFC 3274.
              June 2002.

   CMS        Housley, R.  Cryptographic Message Syntax.
              RFC 3369.  August 2002.

   ESS        Hoffman, P.  Enhanced Security Services for S/MIME.
              RFC 2634.  June 1999.

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

   SHA1       National Institute of Standards and Technology.
              FIPS Pub 180-1: Secure Hash Standard.  17 April 1995.

   STDWORDS   Bradner, S.  Key Words for Use in RFCs to Indicate
              Requirement Levels.  RFC 2119.  March 1997.

   UTF-8      Yergeau, F.  UTF-8, a transformation format of ISO 10646.
              RFC 2279.  January 1998.

   X.208-88   CCITT.  Recommendation X.208: Specification of Abstract
              Syntax Notation One (ASN.1).  1988.

   X.209-88   CCITT.  Recommendation X.209: Specification of Basic
              Encoding Rules for Abstract Syntax Notation One (ASN.1).
              1988.

   X.509-88   CCITT.  Recommendation X.509: The Directory - Authentication
              Framework.  1988.

5.2  Informative References

   ACPROFILE  Farrell, S., and R. Housley.  An Internet Attribute
              Certificate Profile for Authorization.  RFC 3281.
              April 2002.






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   AES        National Institute of Standards and Technology.
              FIPS Pub 197: Advanced Encryption Standard (AES).
              26 November 2001.

   DPD&DPV    Pinkas, D., and R. Housley.  Delegated Path Validation
              and Delegated Path Discovery Protocol Requirements.
              RFC 3379.  September 2002.

   DSS        National Institute of Standards and Technology.
              FIPS Pub 186: Digital Signature Standard.  19 May 1994.

   OCSP       Myers, M., R. Ankney, A. Malpani, S. Galperin, and
              C. Adams.  X.509 Internet Public Key Infrastructure -
              Online Certificate Status Protocol (OCSP).  RFC 2560.
              June 1999.

   PKCS#6     RSA Laboratories.  PKCS #6: Extended-Certificate Syntax
              Standard, Version 1.5.  November 1993.

   RANDOM     Eastlake, D., S. Crocker, and J. Schiller.  Randomness
              Recommendations for Security.  RFC 1750.  December 1994.

   SECREQMTS  National Institute of Standards and Technology.
              FIPS Pub 140-2: Security Requirements for Cryptographic
              Modules.  25 May 2001.

   X.509-97   ITU-T.  Recommendation X.509: The Directory - Authentication
              Framework.  1997.

   X.509-00   ITU-T.  Recommendation X.509: The Directory - Authentication
              Framework.  2000.

6  Security Considerations

   Private signature keys must be protected.  Compromise of the private
   key used to sign firmware packages permits unauthorized parties to
   generate firmware packages that are acceptable to hardware modules.
   Compromise of the hardware module private key permits unauthorized
   parties to generate firmware package load receipts.

   The firmware-decryption key must be protected.  Compromise of the key
   may result in the disclosure of the firmware to unauthorized parties.

   The use of a stale version number in a firmware package cannot
   completely prevent subsequent use of the stale firmware package.
   Despite this shortcoming, the feature is included since it is useful
   in some important situations.  By loading different types of firmware
   packages, each with their own stale firmware version number, until



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   the internal storage for the stale version number is exceeded, the
   user can circumvent the mechanism.  Consider a hardware module that
   has storage for two stale version numbers.  Suppose that FWPKG-A
   version 3 is loaded, indicating that FWPKG-A version 2 is stale.  The
   user can sequentially load the following:


      - FWPKG-B version 8, indicating that FWPKG-B version 4 is stale.
          (Note: The internal storage indicates that FWPKG-A version 2
           and FWPKG-B version 4 are stale.)

      - FWPKG-C version 5, indicating that FWPKG-C version 3 is stale.
          (Note: The internal storage indicates that FWPKG-B version 4
           and FWPKG-C version 3 are stale.)

      - FWPKG-A version 2.

   Since many hardware modules are expected to have very few firmware
   packages written for them, the stale firmware version feature
   provides important protections.  The amount of non-volatile storage
   that needs to be dedicated to saving firmware package identifiers and
   version numbers depends on the number of firmware packages with
   common trust anchors that are likely to be developed for the hardware
   module.

   When firmware packages are encrypted, the source of the firmware
   package must randomly generate firmware-encryption keys.  Also, the
   generation of public/private signature key pairs relies on a random
   numbers.  The use of inadequate pseudo-random number generators
   (PRNGs) to generate cryptographic keys can result in little or no
   security.  An attacker may find it much easier to reproduce the PRNG
   environment that produced the keys, searching the resulting small set
   of possibilities, rather than brute force searching the whole key
   space.  The generation of quality random numbers is difficult.  RFC
   1750 [RANDOM] offers important guidance in this area, and Appendix 3
   of FIPS Pub 186 [DSS] provides one quality PRNG technique.

7  Author Address

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

   housley@vigilsec.com





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Appendix A:  ASN.1 Module

   CMSFirmwareWrapper
       { iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1)
         pkcs-9(9) smime(16) modules(0) cms-firmware-wrap(22) }

   DEFINITIONS IMPLICIT TAGS ::= BEGIN

   IMPORTS
       EnvelopedData, id-data
       FROM CryptographicMessageSyntax
            { iso(1) member-body(2) us(840) rsadsi(113549)
              pkcs(1) pkcs-9(9) smime(16) modules(0) cms-2001(14) };


   -- Firmware Package Content Type and Object Identifier

   id-ct-firmwarePackage OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) ct(1) 16 }

   FirmwarePkgData ::= OCTET STRING


   -- Firmware Package Signed Attributes and Object Identifiers

   id-aa-firmwarePackageID OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) aa(2) 35 }

   FirmwarePackageIdentifier ::= SEQUENCE {
     fwPkgID OBJECT IDENTIFIER,
     verNum INTEGER (0..MAX),
     staleVerNum INTEGER (0..MAX) OPTIONAL }


   id-aa-targetHardwareIDs OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) aa(2) 36 }

   TargetHardwareIdentifiers ::= SEQUENCE OF OBJECT IDENTIFIER


   id-aa-decryptKeyID OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) aa(2) 37 }

   DecryptKeyIdentifier ::= OCTET STRING



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   id-aa-implCryptoAlgs OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) aa(2) 38 }

   ImplementedCryptoAlgorithms ::= SEQUENCE OF OBJECT IDENTIFIER


   id-aa-communityIdentifiers OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) aa(2) 40 }

   CommunityIdentifiers ::= SEQUENCE OF CommunityIdentifier

   CommunityIdentifier ::= CHOICE {
     communityOID OBJECT IDENTIFIER,
     hwModuleList HardwareModules }

   HardwareModules ::= SEQUENCE {
     hwType OBJECT IDENTIFIER,
     hwSerialEntries SEQUENCE OF HardwareSerialEntry }

   HardwareSerialEntry ::= CHOICE {
     single OCTET STRING,
     block SEQUENCE {
       low OCTET STRING,
       high OCTET STRING } }


   -- Firmware Package Unsigned Attributes and Object Identifiers

   id-aa-wrappedFirmwareKey OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) aa(2) 39 }

   WrappedFirmwareKey ::= EnvelopedData
















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   -- Firmware Package Load Receipt Content Type and Object Identifier

   id-ct-firmwareLoadReceipt OBJECT IDENTIFIER ::= {
     iso(1) member-body(2) us(840) rsadsi(113549) pkcs(1) pkcs9(9)
     smime(16) ct(1) 17 }

   FirmwarePackageLoadReceipt ::= SEQUENCE {
     hwType OBJECT IDENTIFIER,
     hwSerialNum OCTET STRING,
     fwPkgID OBJECT IDENTIFIER,
     verNum INTEGER (0..MAX),
     decryptKeyID OCTET STRING OPTIONAL }


   -- Other Name syntax for Hardware Module Name

   id-on-hardwareModuleName OBJECT IDENTIFIER ::= {
     iso(1) identified-organization(3) dod(6) internet(1) security(5)
     mechanisms(5) pkix(7) on(8) 4 }

   HardwareModuleName ::= SEQUENCE {
     hwType OBJECT IDENTIFIER,
     hwSerialNum OCTET STRING }


   END

























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Appendix B:  Change History

   Changes in version -01:

     - Added an optional decryptKeyID to the firmware package
       load receipt.
     - Assigned object identifiers.
     - State that disposition of previously loaded firmware
       package is beyond scope of this document.
     - Update Figure 1 by adding two boxes: one for "Hardware
       Module Type" and one for "Firmware Package Identifier
       and Version Number"
     - Removed redundancy between section 1.2.2 and section 1.2.3
       regarding the stale version number.
     - In section 2.1.2, make it clear that the trust anchor
       itself is not represented in the certificates.
     - In section 2.3.1, require the content type object
       identifier to be set to id-data.
     - Many editorial updates.
































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Full Copyright Statement

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  In addition, the
   ASN.1 module presented in Appendix A may be used in whole or in part
   without inclusion of the copyright notice.  However, this document
   itself may not be modified in any way, such as by removing the
   copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process shall be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.  This
   document and the information contained herein is provided on an "AS
   IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK
   FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
   LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL
   NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY
   OR FITNESS FOR A PARTICULAR PURPOSE.























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