Tls-crypt key parsing issues

[reynir]

If the number of characters in a line is odd the last character will be ignored. Lucky for us this means carriage returns will usually be ignored. However, if a line ends with a space and a carriage return this will cause trouble.

The OpenVPN implementation seems to ignore all whitespace. However, it seems they ignore the last hex digit if there is an odd number of total hex digits(!)
https://github.com/OpenVPN/openvpn/blob/f015643fe23d7847ad45b7763f31bfc6baed2159/src/openvpn/crypto.c#L1257-L1289

Originally posted by @reynir in #189 (comment)