larzcbor

CBOR (RFC 8949) encode/decode. Pure Python, zero dependencies.

CBOR is the IETF's standard binary data format — compact like MessagePack, but an actual internet standard used by WebAuthn/FIDO2, COSE, and IoT (CoAP). larzcbor encodes and decodes the core data model with canonical map ordering.

from larzcbor import encode, decode

encode({"a": 1, "b": [2, 3]})     # b'\xa2aba\x01ab\x82\x02\x03'
decode(encode([1, "two", 3.0, {"x": True}]))

Why

• A standard, not a convention. CBOR is defined by RFC 8949; larzcbor is tested against the RFC's own byte vectors, so its output interoperates with every conformant CBOR tool and the systems that mandate it (WebAuthn attestation, COSE signing, CoAP payloads).
• Canonical output. Map keys are emitted in sorted byte order, so equal values encode to identical bytes — safe to hash or sign (pair with larzcrypt).
• Compact. Binary, with the same small-value efficiency as MessagePack; decodes float16/32/64 for full interop.
• Zero dependencies. No cbor2, no C extension.

Install

pip install larzcbor

Usage

from larzcbor import encode, decode

blob = encode({"user": 42, "roles": ["admin"], "active": True})
decode(blob)     # {'user': 42, 'roles': ['admin'], 'active': True}

Supports None, bool, int, float, str, bytes, list, dict.

larzcbor vs larzpack

Both are compact, canonical, zero-dep binary serializers. Choose larzpack for MessagePack compatibility; choose larzcbor when you need the IETF CBOR standard (WebAuthn/COSE/IoT).

Tests

python -m unittest discover -s tests -v   # 16 tests incl. RFC 8949 vectors

The Larz stack

One of 30+ pure-Python, zero-dependency libraries at github.com/larz-scripter.

License

MIT © larz-scripter