I couldn't find examples of CBOR encoded COSE key objects in COSE working group Examples.
Included in this repository are example test vectors for CBOR encoded COSE key objects. These test vectors were created with pycose.
Some odd modifications had to be done in the generation script gen.py as pycose lacks the ability to
encode public keys. Also, it restricts symmetric keys to AES key lengths and did not support
HMAC-SHA{384,512} key lengths. These missing features were compensated for by editing the CBOR structure
and then re-encoding.
This work is released as public domain / Creative Commons Zero