Restore arti support and create a tutorial

[oxarbitrage]

In the past the Zebra node had the capability of running behind the tor network, it was an effort made by @teor2345 . We never actually made any tests or wrote anything about how to use it and what were their capabilities. Some time after we had to disable the support because of dependency issues (#5492).

This is a list of tasks where the plan is to re enable the support and go a step beyond what we had by detailing what it is possible when zebra runs with arti support:

• Enable arti-client when it upgrades its dependency x25519-dalek #5492

[oxarbitrage]

This idea ended up being a dependency nightmare.

I started by enabling the tor support by reversing the changes that were done to zebra-network Cargo.toml in #5481

Initially started by using the current last version of the 2 crates:

• arti-client: v0.14.0
• tor-rtcompat: v0.10.0

This arti crates use the last versions of base64ct crate while in zebra we are depend on zcash_primitives, that depends on a version of bip0039 that depends on pbkdf2 that depends on password-hash to finally end up depending in an old version of base64ct. A similar issue also happens with zcash_proofs.

While upgrading zcash_primitives and zcash_proofs is maybe doable, there are other places where we are going to need to make changes, specifically into zcash_script crate.

Another option could be forking all the dependencies, however forking and maintaining such of a dependency chain will be problematic for us.

I tried different versions of arti and rtcompat however the dependency differences remain in the newest versions where in older versions other problems arise. There is no much sense in supporting a very old arti version even if that works.

Another approach i tried was to fork arti and downgrade base64ct. This almost worked, however there are some arti crates that depends on another crate which ends up depending in a higher than we can afford in zebra for the base64ct dependency. So that was another dead end.

Finally, @arya2 tried some options with the patch Cargo config option but it was another dead end.

So, considering the significant amount of work we are going to need to make this happen in the current conditions and the timeframe we have to complete the project (1 sprint) we had to abandon this idea for now.

I am pinging @str4d and @nuttycom they can maybe take a look in the future and let us know if there is some plan to make dependency upgrades that make this project a bit easier for us.

[emersonian]

It looks like bumping bip0039 to v0.12 in zcash_primitives now fixes the build. Here's a branch that builds with arti enabled, I haven't tested it yet.

Pulling this off involves upgrading bip0039 in zcash_primitives then releasing new patch versions of each crate that depends on it.