philipschoemig/ber-tlv

Python library for BER-TLV en-/decoding

Python library for BER-TLV en-/decoding.

Glossary

BER

Basic Encoding Rules is a standard encoding format for ASN.1. See X.690 BER encoding on Wikipedia.

TLV

Encoding scheme which consists of the fields tag, length and value. See Type-length-value on Wikipedia.

References

• X.690 BER encoding
• Type-length-value
• ISO 7816-4 Annex D
• EMV - Data Structure

ber-tlv's Issues

Whitespace is removed from XML element text with type ASCII

When parsing a TLV tree from XML all whitespace is removed from the XML element text for a primitive tag. However, if the "Type" attribute is "ASCII" the whitespace must be included.

Example:
<Primitive Tag="0x5F20" Type="ASCII">123 Go!</Primitive>

This will currently produce the following TLV tree:

root
└── 5f20: 313233476f21

But it should be:

root
└── 5f20: 31323320476f21

Use poetry version command to bump package version

Instead of using an external tool like bump2version the poetry command version could be used to increase the package version. For this to work the duplicate version information in src/bertlv/init.py and docs/conf.py must be removed.

init.py

The version variable could be assigned to the package version retrieved from importlib.metadata.version() as suggested in poetry issue #144. Example code:

try:
    import importlib.metadata as importlib_metadata
except ModuleNotFoundError:
    import importlib_metadata

__version__ = importlib_metadata.version(__name__)

See the complete solution in this comment: python-poetry/poetry#2366 (comment)

However, for python version <3.8 this would introduce a dependency to importlib_metadata.

conf.py

The version should be retrieved by accessing the __version__ variable from the bertlv module. Example code:

import bertlv
version = bertlv.__version__

to use it as decoder

Could you please guide me or provide any documentation to use this to decode BER TLV file.
The file is in binary format. When read as binary file, the sample output for the binary data file is as follow:
b'0\x82*\xd1\xa0\x10\x80\t\x18\x11 \x1807+\x05\x00\x81\x01\x00\xa2\x00\xa1\x82*\x8e\xa0\x82\x01\x8e\x80\x01\

Thanks for support

Use pytest-datafiles for predefined test files

Use the pytest plugin datafiles for predefined test/example files, e.g. binary TLV file.

See https://www.openscdp.org/scripts/tutorial/emv/TLV.html for exemplary TLV data.