Cmsex.SignerInfo (cmsex v0.1.0)

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One signer of a SignedData message, as Cmsex.decode/2 reads it (RFC 5652, 5.3). Reading checks the structure only; Cmsex.verify/2 checks the signature.

Fields:

  • :version - 1 with an issuer and serial number, 3 with a subject key identifier.
  • :sid - which certificate signed: {:issuer_and_serial, issuer, serial}, with the issuer as the DER of its Name as received, or {:subject_key_identifier, ski}.
  • :digest_algorithm - the name of the digest algorithm in Cmsex.OID, such as :sha256, or its OID.
  • :signature_algorithm - the name of the signature algorithm, such as :rsa_encryption, :sha256_with_rsa_encryption, :rsassa_pss, :ecdsa_with_sha256 or :ed25519, or its OID.
  • :signature_parameters - for :rsassa_pss, a map with :hash, :mgf_hash, :salt_length and :trailer_field, the defaults filled in; nil otherwise.
  • :signed_attributes - a list of Cmsex.Attribute, in the order of the message, or nil when the signer has none.
  • :unsigned_attributes - a list of Cmsex.Attribute, empty when there are none. These are not covered by the signature: anyone can add, remove or change them.
  • :signature - the signature value. It is also what a signature time-stamp (RFC 3161, appendix A) and a countersignature cover.
  • :deviations - what the library tolerated when reading, against RFC 5652:
    • :signer_info_version - the version does not match the signer identifier;
    • :signed_attributes_not_der - the signed attributes are not in DER; the signature is checked over the bytes as received;
    • :signing_time_encoding - a signing time from 1950 to 2049 written as GeneralizedTime.

Summary

Types

pss_parameters()

The parameters of RSASSA-PSS (RFC 4055, 3.1), with the defaults filled in.

sid()
t()

Functions

attribute(signer_info, type)

The first signed attribute of a type, a name of Cmsex.OID or an OID, or nil.

content_type(signer_info)

The content-type attribute: the type of the signed content, as a name of Cmsex.OID or an OID. :error when it is missing, repeated, or not a single OID.

countersignatures(signer_info, opts \\ [])

The countersignatures of this signer (RFC 5652, 11.4): each a SignerInfo over the signature of this one. They are read, not verified; see the :countersignatures option of Cmsex.verify/2. Takes the limits of Cmsex.decode/2.

message_digest(signer_info)

The message-digest attribute: the digest of the content. :error when it is missing, repeated, or not a single OCTET STRING.

signature(signer_info)

The signature value of the signer. It is what a signature time-stamp covers (RFC 3161, appendix A): the time-stamp request hashes these bytes, and the token goes back in an unsigned attribute with Cmsex.add_unsigned_attribute/4. A countersignature covers it too (RFC 5652, 11.4).

signing_time(signer_info)

The signing-time attribute. It is what the signer claims, not a fact anyone checked. :error when it is missing, repeated or malformed.

unsigned_attribute(signer_info, type)

The first unsigned attribute of a type, such as :time_stamp_token, or nil. Unsigned attributes are not covered by the signature.

Types

pss_parameters()

@type pss_parameters() :: %{
  hash: atom(),
  mgf_hash: atom(),
  salt_length: non_neg_integer(),
  trailer_field: pos_integer()
}

The parameters of RSASSA-PSS (RFC 4055, 3.1), with the defaults filled in.

sid()

@type sid() ::
  {:issuer_and_serial, binary(), integer()}
  | {:subject_key_identifier, binary()}

t()

@type t() :: %Cmsex.SignerInfo{
  deviations: [atom()],
  digest_algorithm: atom() | tuple(),
  raw: map() | nil,
  sid: sid(),
  signature: binary(),
  signature_algorithm: atom() | tuple(),
  signature_parameters: pss_parameters() | nil,
  signed_attributes: [Cmsex.Attribute.t()] | nil,
  unsigned_attributes: [Cmsex.Attribute.t()],
  version: integer()
}

Functions

attribute(signer_info, type)

@spec attribute(t(), atom() | tuple()) :: Cmsex.Attribute.t() | nil

The first signed attribute of a type, a name of Cmsex.OID or an OID, or nil.

content_type(signer_info)

@spec content_type(t()) :: {:ok, atom() | tuple()} | :error

The content-type attribute: the type of the signed content, as a name of Cmsex.OID or an OID. :error when it is missing, repeated, or not a single OID.

countersignatures(signer_info, opts \\ [])

@spec countersignatures(t(), keyword()) :: {:ok, [t()]} | {:error, Cmsex.Error.t()}

The countersignatures of this signer (RFC 5652, 11.4): each a SignerInfo over the signature of this one. They are read, not verified; see the :countersignatures option of Cmsex.verify/2. Takes the limits of Cmsex.decode/2.

message_digest(signer_info)

@spec message_digest(t()) :: {:ok, binary()} | :error

The message-digest attribute: the digest of the content. :error when it is missing, repeated, or not a single OCTET STRING.

signature(signer_info)

@spec signature(t()) :: binary()

The signature value of the signer. It is what a signature time-stamp covers (RFC 3161, appendix A): the time-stamp request hashes these bytes, and the token goes back in an unsigned attribute with Cmsex.add_unsigned_attribute/4. A countersignature covers it too (RFC 5652, 11.4).

signing_time(signer_info)

@spec signing_time(t()) :: {:ok, DateTime.t()} | :error

The signing-time attribute. It is what the signer claims, not a fact anyone checked. :error when it is missing, repeated or malformed.

unsigned_attribute(signer_info, type)

@spec unsigned_attribute(t(), atom() | tuple()) :: Cmsex.Attribute.t() | nil

The first unsigned attribute of a type, such as :time_stamp_token, or nil. Unsigned attributes are not covered by the signature.