Error converting string to bytes

[luisdemarchi]

Hi,

I am using Python 3.7 and with the command: mediaKeyExpanded = HKDFv3().deriveSecrets(mediaK, "Image Keys", 112)

Displays the following error:

TypeError: string argument without an encoding

The solution is to basically change line 49 of the axolotl/kdf/hkdf.py file: mac.update(bytes(info)) for: mac.update(bytes(info, encoding="utf8"))