Most types in ASN.1 has specific tag for them. ``Obj.tag_default`` is
the default tag used during coding process. You can override it with
either ``IMPLICIT`` (using ``impl`` keyword argument), or
-``EXPLICIT`` one (using ``expl`` keyword argument). Both arguments takes
+``EXPLICIT`` one (using ``expl`` keyword argument). Both arguments take
raw binary string, containing that tag. You can **not** set implicit and
explicit tags simultaneously.
Implicit tag is not explicitly shown.
-Two object of the same type, but with different implicit/explicit tags
+Two objects of the same type, but with different implicit/explicit tags
are **not** equal.
-You can get objects effective tag (either default or implicited) through
+You can get object's effective tag (either default or implicited) through
``tag`` property. You can decode it using :py:func:`pyderasn.tag_decode`
function::
Common methods
______________
-All objects have ``ready`` boolean property, that tells if it is ready
-to be encoded. If that kind of action is performed on unready object,
-then :py:exc:`pyderasn.ObjNotReady` exception will be raised.
+All objects have ``ready`` boolean property, that tells if object is
+ready to be encoded. If that kind of action is performed on unready
+object, then :py:exc:`pyderasn.ObjNotReady` exception will be raised.
-All objects have ``copy()`` method, returning its copy, that can be safely
-mutated.
+All objects have ``copy()`` method, that returns their copy, that can be
+safely mutated.
.. _decoding:
``Any``/``OctetString``-s
When any of those fields is automatically decoded, then ``.defined``
-attribute contains ``(OID, value)`` tuple. OID tell by which OID it was
-defined, ``value`` contains corresponding decoded value. For example
+attribute contains ``(OID, value)`` tuple. ``OID`` tells by which OID it
+was defined, ``value`` contains corresponding decoded value. For example
above, ``content_info["content"].defined == (id_signedData,
signed_data)``.
+.. _defines_by_path_kwarg:
+
defines_by_path kwarg
_____________________
Pay attention for :py:func:`pyderasn.decode_path_defby` and ``any``.
First function is useful for path construction when some automatic
-decoding is already done. ``any`` is used for human readability and
-means literally any value it meet -- useful for sequence and set of-s.
+decoding is already done. ``any`` means literally any value it meet --
+useful for SEQUENCE/SET OF-s.
Primitive types
---------------
def main(): # pragma: no cover
import argparse
parser = argparse.ArgumentParser(description="PyDERASN ASN.1 DER decoder")
+ parser.add_argument(
+ "--skip",
+ type=int,
+ default=0,
+ help="Skip that number of bytes from the beginning",
+ )
parser.add_argument(
"--oids",
help="Python path to dictionary with OIDs",
"--schema",
help="Python path to schema definition to use",
)
+ parser.add_argument(
+ "--defines-by-path",
+ help="Python path to decoder's defines_by_path",
+ )
parser.add_argument(
"DERFile",
type=argparse.FileType("rb"),
help="Path to DER file you want to decode",
)
args = parser.parse_args()
+ args.DERFile.seek(args.skip)
der = memoryview(args.DERFile.read())
args.DERFile.close()
oids = obj_by_path(args.oids) if args.oids else {}
pprinter = partial(pprint, big_blobs=True)
else:
schema, pprinter = generic_decoder()
- obj, tail = schema().decode(der)
+ obj, tail = schema().decode(
+ der,
+ defines_by_path=(
+ None if args.defines_by_path is None
+ else obj_by_path(args.defines_by_path)
+ ),
+ )
print(pprinter(obj, oids=oids))
if tail != b"":
print("\nTrailing data: %s" % hexenc(tail))