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.


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 =
str ='abc')
sequence = [ int, str ] )

Example - constructing a SET

int =
str ='abc')
set = [ int, str ] )
Included Modules
[RW] tagging

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.

Class Public methods [, tag, tagging, tag_class ]) => Primitive

value: is mandatory.

tag: optional, may be specified for tagged values. If no tag is specified, the UNIVERSAL tag corresponding to the Primitive sub-class is used by default.

tagging: may be used as an encoding hint to encode a value either explicitly or implicitly, see ASN1 for possible values.

tag_class: if tag and tagging are nil then this is set to :UNIVERSAL by default. If either tag or tagging are set then :CONTEXT_SPECIFIC is used as the default. For possible values please cf. ASN1.


int =
zero_tagged_int =, 0, :IMPLICIT)
private_explicit_zero_tagged_int =, 0, :EXPLICIT, :PRIVATE)
static VALUE
ossl_asn1_initialize(int argc, VALUE *argv, VALUE self)
    VALUE value, tag, tagging, tag_class;
    int default_tag;

    rb_scan_args(argc, argv, "13", &value, &tag, &tagging, &tag_class);
    default_tag = ossl_asn1_default_tag(self);

    if (default_tag == -1 || argc > 1) {
            ossl_raise(eASN1Error, "must specify tag number");
        if(!NIL_P(tagging) && !SYMBOL_P(tagging))
            ossl_raise(eASN1Error, "invalid tagging method");
        if(NIL_P(tag_class)) {
            if (NIL_P(tagging))
                tag_class = sym_UNIVERSAL;
                tag_class = sym_CONTEXT_SPECIFIC;
            ossl_raise(eASN1Error, "invalid tag class");
        tag = INT2NUM(default_tag);
        tagging = Qnil;
        tag_class = sym_UNIVERSAL;
    ossl_asn1_set_tag(self, tag);
    ossl_asn1_set_value(self, value);
    ossl_asn1_set_tagging(self, tagging);
    ossl_asn1_set_tag_class(self, tag_class);
    ossl_asn1_set_indefinite_length(self, Qfalse);
    if (default_tag == V_ASN1_BIT_STRING)
        rb_ivar_set(self, sivUNUSED_BITS, INT2FIX(0));

    return self;
Instance Public methods
asn1_ary.each { |asn1| block } => asn1_ary

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


asn1_ary.each do |asn1|
  puts asn1
static VALUE
ossl_asn1cons_each(VALUE self)
    rb_block_call(ossl_asn1_get_value(self), id_each, 0, 0, 0, 0);

    return self;
asn1.to_der => DER-encoded String
static VALUE
ossl_asn1cons_to_der(VALUE self)
    VALUE ary, str;
    long i;
    int indef_len;

    indef_len = RTEST(ossl_asn1_get_indefinite_length(self));
    ary = rb_convert_type(ossl_asn1_get_value(self), T_ARRAY, "Array", "to_a");
    str = rb_str_new(NULL, 0);
    for (i = 0; i < RARRAY_LEN(ary); i++) {
        VALUE item = RARRAY_AREF(ary, i);

        if (indef_len && rb_obj_is_kind_of(item, cASN1EndOfContent)) {
            if (i != RARRAY_LEN(ary) - 1)
                ossl_raise(eASN1Error, "illegal EOC octets in value");

             * EOC is not really part of the content, but we required to add one
             * at the end in the past.

        item = ossl_to_der_if_possible(item);
        rb_str_append(str, item);

    return to_der_internal(self, 1, indef_len, str);