I've read, the design is awesome. And I have to suggestion. 1. Master keys should be able to store in cold storage. i.e. The keys we currently using in memo shouldn't be master keys.
2. Change prefix to other code, rather than 0x6d*. Because this protocol may become a infrastructure to identify indiviuals on chain, it is not only belonging to memo protocol.
Well, I thought 0x6d was designed as memo only protocols, though MIP-0003 seems more than a memo protocol. With further designing, 0x6d2[0-2] can be the infrastructure of PKI on BCH.
I think change 0x6d2[0-2] to a long prefix is better. 0x6d20 -> 0x6d2000 0x6d21 -> 0x6d2001 0x6d20 -> 0x6d2002 [0x6d2003, 0x6d20ff] = reserved for futher expantion about keys relation
related question (currently working on script decoding) - is the MEMO plan to span beyond the 6dxx space ? The protocol seems to stick to 6d - is there room for "extras"?