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:
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