Yes, the bash script could be made more portable. Also there are some GNU-specific sed features used, but I'm sure that could be changed to be more portable as

Yes, the bash script could be made more portable. Also there are some GNU-specific sed features used, but I'm sure that could be changed to be more portable as well. Python or openssl is used for some base64 encoding. I like using shell scripts for projects like this because of the power of piping commands/functions and doing line-based processing with e.g. sed.