Class: Longfellow::Attribute

Inherits:
Object
  • Object
show all
Defined in:
lib/longfellow/attribute.rb

Overview

A claim that the prover must open and the verifier checks: a single mdoc attribute identified by its namespace and element identifier, together with the expected value encoded as the raw bytes of its CBOR representation.

Mirrors the C ‘RequestedAttribute` struct. The fixed-size C buffers bound the lengths: namespace_id <= 64, id <= 32, cbor_value <= 64 bytes.

Constant Summary collapse

MAX_NAMESPACE = 
64
MAX_ID = 
32
MAX_CBOR_VALUE = 
64

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(namespace_id:, id:, cbor_value:) ⇒ Attribute

Returns a new instance of Attribute.

Parameters:

  • namespace_id (String) —

    e.g. “org.iso.18013.5.1”

  • id (String) —

    element identifier, e.g. “age_over_18”

  • cbor_value (String) —

    raw CBOR-encoded value bytes



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# File 'lib/longfellow/attribute.rb', line 20

def initialize(namespace_id:, id:, cbor_value:)
  @namespace_id = String(namespace_id).b
  @id = String(id).b
  @cbor_value = String(cbor_value).b
  validate!
end

Instance Attribute Details

#cbor_value ⇒ Object (readonly)

Returns the value of attribute cbor_value.



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# File 'lib/longfellow/attribute.rb', line 15

def cbor_value
  @cbor_value
end

#id ⇒ Object (readonly)

Returns the value of attribute id.



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# File 'lib/longfellow/attribute.rb', line 15

def id
  @id
end

#namespace_id ⇒ Object (readonly)

Returns the value of attribute namespace_id.



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# File 'lib/longfellow/attribute.rb', line 15

def namespace_id
  @namespace_id
end

Class Method Details

.coerce(obj) ⇒ Object

Coerce a Hash or Attribute into an Attribute.



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# File 'lib/longfellow/attribute.rb', line 28

def self.coerce(obj)
  case obj
  when Attribute then obj
  when Hash then new(**obj.transform_keys(&:to_sym))
  else
    raise ArgumentError,
          "expected Longfellow::Attribute or Hash, got #{obj.class}"
  end
end

Instance Method Details

#write_to(struct) ⇒ Object

Populate a C::RequestedAttribute struct (backed by zeroed memory).



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# File 'lib/longfellow/attribute.rb', line 39

def write_to(struct)
  ptr = struct.to_ptr
  ptr.put_bytes(struct.offset_of(:namespace_id), @namespace_id) unless @namespace_id.empty?
  ptr.put_bytes(struct.offset_of(:id), @id) unless @id.empty?
  ptr.put_bytes(struct.offset_of(:cbor_value), @cbor_value) unless @cbor_value.empty?
  struct[:namespace_len] = @namespace_id.bytesize
  struct[:id_len] = @id.bytesize
  struct[:cbor_value_len] = @cbor_value.bytesize
  struct
end