The 2nd return value of parse_message_2, id_cred_r, currently has values like [10] or [162, 2, 96, 8, 161, 1, 165, 1, 2, 2, ...]. What it represents is the binary value of ID_CRED_R, a byte string, and it should be represented as such in Python.

(Haven't had a look at the Python implementation yet, might manage a PR.)