The top-level class representing any ASN.1 object. When parsed by OpenSSL::ASN1.decode, tagged values are always represented by an instance of ASN1Data.
When encoding an ASN.1 type it is inherently clear what original type (e.g. INTEGER, OCTET STRING etc.) this value has, regardless of its tagging. But opposed to the time an ASN.1 type is to be encoded, when parsing them it is not possible to deduce the "real type" of tagged values. This is why tagged values are generally parsed into ASN1Data instances, but with a different outcome for implicit and explicit tagging.
An implicitly 1-tagged INTEGER value will be parsed as an ASN1Data with
tag equal to 1
tag_class equal to :CONTEXT_SPECIFIC
value equal to a String that carries the raw encoding of the INTEGER.
This implies that a subsequent decoding step is required to completely decode implicitly tagged values.
An explicitly 1-tagged INTEGER value will be parsed as an ASN1Data with
tag equal to 1
tag_class equal to :CONTEXT_SPECIFIC
value equal to an Array with one single element, an instance of OpenSSL::ASN1::Integer, i.e. the inner element is the non-tagged primitive value, and the tagging is represented in the outer ASN1Data
int = OpenSSL::ASN1::Integer.new(1, 0, :IMPLICIT) # implicit 0-tagged seq = OpenSSL::ASN1::Sequence.new( [int] ) der = seq.to_der asn1 = OpenSSL::ASN1.decode(der) # pp asn1 => #<OpenSSL::ASN1::Sequence:0x87326e0 # @indefinite_length=false, # @tag=16, # @tag_class=:UNIVERSAL, # @tagging=nil, # @value= # [#<OpenSSL::ASN1::ASN1Data:0x87326f4 # @indefinite_length=false, # @tag=0, # @tag_class=:CONTEXT_SPECIFIC, # @value="\x01">]> raw_int = asn1.value[0] # manually rewrite tag and tag class to make it an UNIVERSAL value raw_int.tag = OpenSSL::ASN1::INTEGER raw_int.tag_class = :UNIVERSAL int2 = OpenSSL::ASN1.decode(raw_int) puts int2.value # => 1
int = OpenSSL::ASN1::Integer.new(1, 0, :EXPLICIT) # explicit 0-tagged seq = OpenSSL::ASN1::Sequence.new( [int] ) der = seq.to_der asn1 = OpenSSL::ASN1.decode(der) # pp asn1 => #<OpenSSL::ASN1::Sequence:0x87326e0 # @indefinite_length=false, # @tag=16, # @tag_class=:UNIVERSAL, # @tagging=nil, # @value= # [#<OpenSSL::ASN1::ASN1Data:0x87326f4 # @indefinite_length=false, # @tag=0, # @tag_class=:CONTEXT_SPECIFIC, # @value= # [#<OpenSSL::ASN1::Integer:0x85bf308 # @indefinite_length=false, # @tag=2, # @tag_class=:UNIVERSAL # @tagging=nil, # @value=1>]>]> int2 = asn1.value[0].value[0] puts int2.value # => 1
Never nil
. A boolean value indicating whether the encoding
uses indefinite length (in the case of parsing) or whether an indefinite
length form shall be used (in the encoding case). In DER, every value uses
definite length form. But in scenarios where large amounts of data need to
be transferred it might be desirable to have some kind of streaming support
available. For example, huge OCTET STRINGs are preferably sent in
smaller-sized chunks, each at a time. This is possible in BER by setting
the length bytes of an encoding to zero and by this indicating that the
following value will be sent in chunks. Indefinite length encodings are
always constructed. The end of such a stream of chunks is indicated by
sending a EOC (End of Content) tag. SETs and SEQUENCEs may use an
indefinite length encoding, but also primitive types such as e.g. OCTET
STRINGS or BIT STRINGS may leverage this functionality (cf. ITU-T X.690).
Never nil
. A boolean value indicating whether the encoding
uses indefinite length (in the case of parsing) or whether an indefinite
length form shall be used (in the encoding case). In DER, every value uses
definite length form. But in scenarios where large amounts of data need to
be transferred it might be desirable to have some kind of streaming support
available. For example, huge OCTET STRINGs are preferably sent in
smaller-sized chunks, each at a time. This is possible in BER by setting
the length bytes of an encoding to zero and by this indicating that the
following value will be sent in chunks. Indefinite length encodings are
always constructed. The end of such a stream of chunks is indicated by
sending a EOC (End of Content) tag. SETs and SEQUENCEs may use an
indefinite length encoding, but also primitive types such as e.g. OCTET
STRINGS or BIT STRINGS may leverage this functionality (cf. ITU-T X.690).
Carries the value of a ASN.1 type. Please confer Constructive and Primitive for the mappings between ASN.1 data types and Ruby classes.
value: Please have a look at Constructive and Primitive to see how Ruby types are mapped to ASN.1 types and vice versa.
tag: An Integer indicating the tag number.
tag_class: A Symbol indicating the tag class. Please cf. ASN1 for possible values.
asn1_int = OpenSSL::ASN1Data.new(42, 2, :UNIVERSAL) # => Same as OpenSSL::ASN1::Integer.new(42) tagged_int = OpenSSL::ASN1Data.new(42, 0, :CONTEXT_SPECIFIC) # implicitly 0-tagged INTEGER
static VALUE ossl_asn1data_initialize(VALUE self, VALUE value, VALUE tag, VALUE tag_class) { if(!SYMBOL_P(tag_class)) ossl_raise(eASN1Error, "invalid tag class"); ossl_asn1_set_tag(self, tag); ossl_asn1_set_value(self, value); ossl_asn1_set_tag_class(self, tag_class); ossl_asn1_set_indefinite_length(self, Qfalse); return self; }
Encodes this ASN1Data into a DER-encoded String value. The result is DER-encoded except for the possibility of indefinite length forms. Indefinite length forms are not allowed in strict DER, so strictly speaking the result of such an encoding would be a BER-encoding.
static VALUE ossl_asn1data_to_der(VALUE self) { VALUE value = ossl_asn1_get_value(self); if (rb_obj_is_kind_of(value, rb_cArray)) return ossl_asn1cons_to_der(self); else { if (RTEST(ossl_asn1_get_indefinite_length(self))) ossl_raise(eASN1Error, "indefinite length form cannot be used " \ "with primitive encoding"); return ossl_asn1prim_to_der(self); } }