ExIcaoVds.Header (ex_icao_vds v0.3.2)

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VDS header struct and binary encoder/decoder.

Binary format

<<
  0xDC,                      # magic constant (1 byte)
  version,                   # 0x04 (1 byte)
  country_c40::2,            # C40 of 3-char ISO country code (2 bytes)
  signer_id_len,             # byte length of following C40 (1 byte)
  signer_id_c40::n,          # C40-encoded signer identifier (n bytes)
  ref_type,                  # 0x01 = key_reference, 0x02 = cert_reference (1 byte)
  ref_len,                   # byte length of reference (1 byte)
  ref::m,                    # raw reference bytes (m bytes)
  issue_bcd_day,             # document issue date, BCD (1 byte)
  issue_bcd_month,           # BCD (1 byte)
  issue_bcd_year,            # year (00–99, century inferred by pivot), BCD (1 byte)
  sig_bcd_day,               # signature creation date, BCD (1 byte)
  sig_bcd_month,             # BCD (1 byte)
  sig_bcd_year,              # year (00–99, century inferred by pivot), BCD (1 byte)
  feature_definition_reference, # (1 byte)
  document_type_category     # ASCII char code (1 byte)
>>

BCD encoding: each byte stores a two-decimal-digit value as high_nibble * 10 + low_nibble, e.g. day 28 → 0x28.

The ref_type byte distinguishes key-reference mode (public_key / pinned_key) from certificate-reference mode (x509). The trust_mode field in the struct mirrors this distinction.

Summary

Types

t()
trust_mode()

Functions

decode(bytes)

Decodes header bytes from the start of bytes. Returns {:ok, header, remaining_bytes} or {:error, ExIcaoVds.Error.t()}.

encode(h)

Encodes a Header struct into binary bytes. Returns {:ok, binary} or {:error, ExIcaoVds.Error.t()}.

Types

t()

@type t() :: %ExIcaoVds.Header{
  certificate_reference: binary() | nil,
  document_issue_date: Date.t() | nil,
  document_type_category: String.t(),
  feature_definition_reference: non_neg_integer(),
  issuing_country: String.t(),
  key_reference: String.t() | nil,
  magic_constant: non_neg_integer(),
  raw: binary() | nil,
  signature_creation_date: Date.t() | nil,
  signer_identifier: String.t(),
  trust_mode: trust_mode(),
  version: non_neg_integer()
}

trust_mode()

@type trust_mode() :: :x509 | :public_key | :pinned_key | :custom

Functions

decode(bytes)

@spec decode(binary()) :: {:ok, t(), binary()} | {:error, ExIcaoVds.Error.t()}

Decodes header bytes from the start of bytes. Returns {:ok, header, remaining_bytes} or {:error, ExIcaoVds.Error.t()}.

encode(h)

@spec encode(t()) :: {:ok, binary()} | {:error, ExIcaoVds.Error.t()}

Encodes a Header struct into binary bytes. Returns {:ok, binary} or {:error, ExIcaoVds.Error.t()}.