That is great. My app is going to be open source and if you want I can test it in alpha mode. It will make a good example of accessing the memo private key.
Anyway I will start with a custom_json scope on SC and a dummy memo private key.
Do you know where to get the encryption function? I had a look at SteemJS and now looking at dSteem, which looks more suited for that but a bit stuck at the moment...
Steem.js has methods to encode / decode message see https://steemit.com/esteem/@good-karma/how-to-encrypt-message-or-memo-on-steem-df860f4d8e3ec
Thanks, appreciate the help!