TargetsModule.asn1

TargetsModule DEFINITIONS AUTOMATIC TAGS ::= BEGIN

  EXPORTS TargetsMetadata, Target;

  IMPORTS BinaryData,
          Filename,
          Hashes,
          Identifier,
          Keyids,
          Length,
          Natural,
          Paths,
          Positive,
          PublicKeys,
          StrictFilename,
          Threshold FROM CommonModule;

  TargetsMetadata ::= SEQUENCE {
    -- Allowed to have no targets at all.
    numberOfTargets Natural,
    -- Metadata about unencrypted images on a repository.
    targets         Targets,
    -- Delegations are optional.
    delegations     TargetsDelegations OPTIONAL,
    -- https://tools.ietf.org/html/rfc6025#section-2.4.2
    ...
  }

  -- Adjust length of SEQUENCE OF to your needs.
  Targets           ::= SEQUENCE (SIZE(1..128)) OF TargetAndCustom
  TargetAndCustom   ::= SEQUENCE {
    -- The filename, length, and hashes of unencrypted images on a repository.
    target  Target,
    -- This attribute is used to specify additional information, such as which
    -- images should be installed by which ECUs, and metadata about encrypted
    -- images.
    custom  Custom OPTIONAL
  }
  Target ::= SEQUENCE {
    filename        Filename,
    length          Length,
    numberOfHashes  Length,
    hashes          Hashes
  }
  Custom ::= SEQUENCE {
    -- NOTE: The following attributes are specified by both the image and
    -- director repositories.
    -- The release counter is used to prevent rollback attacks on images when
    -- only the director repository is compromised.
    -- Every ECU should check that the release counter of its latest image is
    -- greater than or equal to the release counter of its previous image.
    releaseCounter        Natural OPTIONAL,
    -- The hardware identifier is used to prevent the director repository,
    -- when it is compromised, from choosing images for an ECU that were not
    -- meant for it.
    -- Every ECU should check that the hardware ID of its latest image matches
    -- its hardware ID.
    -- An OEM MAY define other types of information to further restrict the
    -- choices that can be made by a compromised director repository.
    hardwareIdentifier    Identifier OPTIONAL,
    -- NOTE: The following attributes are specified only by the director
    -- repository.
    -- The ECU identifier specifies information, e.g., serial numbers, that the
    -- director uses to point ECUs as to which images they should install.
    -- Every ECU should check that the ECU ID of its latest image matches its
    -- own ECU ID.
    ecuIdentifier         Identifier OPTIONAL,
    -- This attribute MAY be used by the director to encrypt images per ECU.
    encryptedTarget       Target OPTIONAL,
    -- This attribute MAY be used if ECU keys are asymmetric, and a per-image
    -- symmetric encryption key is desired for faster decryption of images.
    -- In that case, the director would use the asymmetric ECU key to encrypt
    -- this symmetric key.
    encryptedSymmetricKey EncryptedSymmetricKey OPTIONAL,
    ...
  }
  EncryptedSymmetricKey ::= SEQUENCE {
    -- This is the symmetric key type.
    encryptedSymmetricKeyType   EncryptedSymmetricKeyType,
    -- This is the symmetric key encrypted using the asymmetric ECU key.
    encryptedSymmetricKeyValue  BinaryData
  }
  EncryptedSymmetricKeyType ::= ENUMERATED {aes128, aes192, aes256, ...}

  -- https://github.com/theupdateframework/taps/blob/master/tap3.md
  TargetsDelegations  ::= SEQUENCE {
    -- The public keys of all delegatees.
    numberOfKeys        Length,
    keys                PublicKeys,
    -- The role name, filename, public keys, and threshold of a delegatee.
    numberOfDelegations Length,
    -- A list of paths to roles, listed in order of priority.
    delegations         PrioritizedPathsToRoles
  }

  -- Adjust length of SEQUENCE OF to your needs.
  PrioritizedPathsToRoles ::= SEQUENCE (SIZE(1..8)) OF PathsToRoles
  PathsToRoles ::= SEQUENCE {
    -- A list of image/target paths entrusted to these roles.
    numberOfPaths   Length,
    paths           Paths,
    -- A list of roles required to sign the same metadata about the matching
    -- targets/images.
    numberOfRoles   Length,
    roles           MultiRoles,
    -- Whether or not this delegation is terminating.
    terminating     BOOLEAN DEFAULT FALSE
  }

  -- Adjust length of SEQUENCE OF to your needs.
  MultiRoles ::= SEQUENCE (SIZE(1..8)) OF MultiRole
  MultiRole ::= SEQUENCE {
    -- The rolename (e.g., "supplierA-dev").
    -- No known path separator allowed in a rolename.
    rolename        StrictFilename,
    -- The public keys used by this role.
    numberOfKeyids  Length,
    keyids          Keyids,
    -- The threshold number of these keys.
    threshold       Threshold
  }

END