123456789_123456789_123456789_123456789_123456789_

Class: OpenSSL::ASN1::Constructive

Relationships & Source Files
Super Chains via Extension / Inclusion / Inheritance
Class Chain:
self, ASN1Data
Instance Chain:
self, Enumerable, ASN1Data
Inherits: OpenSSL::ASN1::ASN1Data
Defined in: ext/openssl/ossl_asn1.c

Overview

The parent class for all constructed encodings. The value attribute of a Constructive is always an Array. Attributes are the same as for ASN1Data, with the addition of #tagging.

SET and SEQUENCE

Most constructed encodings come in the form of a SET or a SEQUENCE. These encodings are represented by one of the two sub-classes of Constructive:

  • OpenSSL::ASN1::Set

  • OpenSSL::ASN1::Sequence

Please note that tagged sequences and sets are still parsed as instances of ASN1Data. Find further details on tagged values there.

Example - constructing a SEQUENCE

int = OpenSSL::ASN1::Integer.new(1)
str = OpenSSL::ASN1::PrintableString.new('abc')
sequence = OpenSSL::ASN1::Sequence.new( [ int, str ] )

Example - constructing a SET

int = OpenSSL::ASN1::Integer.new(1)
str = OpenSSL::ASN1::PrintableString.new('abc')
set = OpenSSL::ASN1::Set.new( [ int, str ] )

Infinite length primitive values

The only case where Constructive is used directly is for infinite length encodings of primitive values. These encodings are always constructed, with the contents of the value Array being either UNIVERSAL non-infinite length partial encodings of the actual value or again constructive encodings with infinite length (i.e. infinite length primitive encodings may be constructed recursively with another infinite length value within an already infinite length value). Each partial encoding must be of the same UNIVERSAL type as the overall encoding. The value of the overall encoding consists of the concatenation of each partial encoding taken in sequence. The value array of the outer infinite length value must end with a OpenSSL::ASN1::EndOfContent instance.

Please note that it is not possible to encode Constructive without the infinite_length attribute being set to true, use OpenSSL::ASN1::Sequence or OpenSSL::ASN1::Set in these cases instead.

Example - Infinite length OCTET STRING

partial1 = OpenSSL::ASN1::OctetString.new("\x01")
partial2 = OpenSSL::ASN1::OctetString.new("\x02")
inf_octets = OpenSSL::ASN1::Constructive.new( [ partial1,
                                                partial2,
                                                OpenSSL::ASN1::EndOfContent.new ],
                                              OpenSSL::ASN1::OCTET_STRING,
                                              nil,
                                              :UNIVERSAL )
# The real value of inf_octets is "\x01\x02", i.e. the concatenation
# of partial1 and partial2
inf_octets.infinite_length = true
der = inf_octets.to_der
asn1 = OpenSSL::ASN1.decode(der)
puts asn1.infinite_length # => true

Class Method Summary

ASN1Data - Inherited

.new

value: Please have a look at Constructive and Primitive to see how Ruby types are mapped to ASN.1 types and vice versa.

Instance Attribute Summary

  • #tagging rw

    May be used as a hint for encoding a value either implicitly or explicitly by setting it either to :IMPLICIT or to :EXPLICIT.

ASN1Data - Inherited

#infinite_length

Never nil.
#tag

A Number representing the tag number of this ASN1Data.
#tag_class

A Symbol representing the tag class of this ASN1Data.
#value

Carries the value of a ASN.1 type.

Instance Method Summary

ASN1Data - Inherited

#to_der

Encodes this ASN1Data into a DER-encoded String value.

Constructor Details

.new(value [, tag, tagging, tag_class ]) ⇒ Primitive

Alias for Primitive.new.

Instance Attribute Details

#tagging (rw)

May be used as a hint for encoding a value either implicitly or explicitly by setting it either to :IMPLICIT or to :EXPLICIT. tagging is not set when a ASN.1 structure is parsed using OpenSSL::ASN1.decode.

Instance Method Details

#each {|asn1| ... } ⇒ 1

Calls block once for each element in self, passing that element as parameter asn1. If no block is given, an enumerator is returned instead.

Example

asn1_ary.each do |asn1|
  puts asn1
end

#to_der ⇒ DER-encoded String

See ASN1Data#to_der for details.