Enable user-friendly seed backup and recovery.

[nuttycom]

Is your feature request related to a problem? Please describe.

Having to write down 24 (or 25, as #26 suggests) words in a secure fashion in order to make it possible to recover one's wallet introduces a huge amount of friction to user onboarding. There has to be a better way.

Describe the solution you'd like

There is a fundamental tradeoff between the security of the backed-up data and the ease of backup, and there's no universal solution that allows both "I convinced a stranger in the coffee shop to install a Zcash wallet and they had an easy time of it that didn't require writing down seed words or having a hardware token" and "a new user installing a Zcash wallet has reasonable defenses against nation-state actors who can subvert security controls on iCloud/Google storage" to be true.

Therefore, solutions like the following should be considered:

• A user doesn't have to back up a seed phrase until their wallet has received funds.
• A user doesn't have to back up a seed phrase unless their wallet balance has exceeded some threshold - i.e., consider the ZEC in the wallet to be like cash - it would be an unusual person who would store more than a few hundred dollars in their physical wallet, due to the risk of loss.
  • Perhaps for this approach, seed backup isn't the right thing? Maybe instead cloud backup of a spending key for a single "pocket money" account could help balance requirements between ease of use and security; if you have a "pocket money" account, you can later upgrade to a "vault" account by writing down the seed more securely? The UX gets really annoying if you have too much money in a "pocket money account"?
• If a user has a hardware token available.
• ??? We need more ideas here.

[jswihart]

Edge uses a hashed user name / password supported by its hosted infrastructure, which provides a much more familiar user experience. The whitepaper is here: https://edge.app/wp-content/uploads/2018/09/2017-10-Edge-White-Paper.pdf

[nuttycom]

Edge uses a hashed user name / password supported by its hosted infrastructure, which provides a much more familiar user experience. The whitepaper is here: https://edge.app/wp-content/uploads/2018/09/2017-10-Edge-White-Paper.pdf

This looks like essentially a "1Password" model - private data encrypted by client-side keys, stored by the upstream provider (and potentially exportable to your own data store). The interesting bit is here:

Edge Core utilizes a semi-decentralized, peer-to-peer network of data-sync backup servers running the
Git protocol and software. Referred to as ‘sync-servers’, this pool of Git servers only hosts data that is
pre-encrypted by the client devices running Edge Core. These are true peer-to-peer servers in that there
are no primary or secondary servers, however all sync-servers and the auth-server are operated by Edge.
A client can connect to any of the sync servers to upload or download data. Any new or modified data
sent to a sync-server is automatically replicated to other sync-servers, utilizing the Git protocol to
resolve conflicts and provide modification history and rollback if needed

I'm curious how they use the Git protocol to resolve conflicts; since the stored data is encrypted, such conflict resolution would have to be done client-side. Perhaps they do something like use per-client branches, and then locally handle "merges"?

Git isn't a great choice here, although I can see why they went with it because it's an easy solution. Billing them as "peer-to-peer" is maybe true but misleading, because it's not clear that it is possible to rely on your own git server here.