# Overview

Hush Lightwalletd is a fork of [lightwalletd](https://github.com/adityapk00/lightwalletd) original from Zcash (ZEC).

It is a backend service that provides a bandwidth-efficient interface to the Hush blockchain for the [SilentDragonLite cli](https://git.hush.is/hush/silentdragonlite-light-cli) and [SilentDragonLite](https://git.hush.is/hush/SilentDragonLite)

## Changes from upstream lightwalletd
This version of lightwalletd extends lightwalletd and:

* Adds support for HUSH
* Adds support for transparent addresses
* Adds several new RPC calls for lightclients
* Lots of perf improvements
  * Replaces SQLite with in-memory cache for Compact Blocks
  * Replace local Txstore, delegating Tx lookups to hushd
  * Remove the need for a separate ingestor

## Running your own SDL lightwalletd

#### 0. First, install Go
You will need Go >= 1.13 which you can download from the official [download page](https://golang.org/dl/) or install via your OS package manager.

This [installation](https://golang.org/doc/install) document shows how to do it on various OS's.

If you're using Ubuntu, try:

```
$ sudo apt install golang
```

#### 1. Run a Hush node.
Either compile or build the [Hush Daemon (hushd)](https://git.hush.is/hush/hush3).

Next, change your HUSH3.conf file to something like the following:

```
rpcuser=user-CHANGETHIS
rpcpassword=pass-CHANGETHIS
rpcport=18031
server=1
daemon=0
txindex=1
rpcworkqueue=256
rpcallowip=127.0.0.1
rpcbind=127.0.0.1
```

Then start `hushd` in your command window. You might need to run with `-reindex` the first time if you are enabling the `txindex` or `insightexplorer` options for the first time. The reindex might take a while.

#### 2. Get a TLS certificate and run the Lightwalletd frontend
First, get a TLS certificate:

On Ubuntu Linux, **I SUGGEST YOU DO NOT USE SNAPD** and just ```sudo apt install certbot``` and then start on [Step 7 of these instructions by the EFF](https://certbot.eff.org/instructions)

Next you decide how you want to setup lightwalletd - with or without NGINX.

##### Option A: "Let's Encrypt" certificate using NGINX as a reverse proxy
If you running a public-facing server, the easiest way to obtain a certificate is to use a NGINX reverse proxy and get a Let's Encrypt certificate.

Create a new section for the NGINX reverse proxy:
```
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    
    server_name your_host.net;

    ssl_certificate /etc/letsencrypt/live/your_host.net/fullchain.pem; # managed by Certbot
    ssl_certificate_key /etc/letsencrypt/live/your_host.net/privkey.pem; # managed by Certbot
    include /etc/letsencrypt/options-ssl-nginx.conf; # managed by Certbot
    ssl_dhparam /etc/letsencrypt/ssl-dhparams.pem; # managed by Certbot
        
    location / {
        # Replace localhost:9067 with the address and port of your gRPC server if using a custom port
    	grpc_pass grpc://your_host.net:9067;
    }
}
```

Then run the lightwalletd frontend with the following (Note: we use the "-no-tls" option as we are using NGINX as a reverse proxy and letting it handle the TLS authentication):

```
 go run cmd/server/main.go -bind-addr your_host.net:9067 -conf-file ~/.komodo/HUSH3/HUSH3.conf -no-tls
```

##### Option B: "Let's Encrypt" certificate just using lightwalletd without NGINX
The other option is to configure lightwalletd to handle its own TLS authentication. Once you have a certificate that you want to use (from a certificate authority), pass the certificate to the frontend as follows:

```
 go run cmd/server/main.go -bind-addr 127.0.0.1:9067 -conf-file ~/.komodo/HUSH3/HUSH3.conf -tls-cert /etc/letsencrypt/live/YOURWEBSITE/fullchain.pem -tls-key /etc/letsencrypt/live/YOURWEBSITE/privkey.pem
```

#### 3. Point the `silentdragonlite-cli` to this server
You should start seeing the frontend ingest and cache the Hush blocks after ~15 seconds. 

Now, connect to your server! (Substitute below)
```
 git clone https://git.hush.is/hush/silentdragonlite-cli
 cd silentdragonlite-cli
```

##### Install deps for cargo on VPS https://doc.rust-lang.org/cargo/getting-started/installation.html
```
sudo apt install -y cargo
```
then

```
 cargo build --release
 ./target/release/silentdragonlite-cli --server https://lite.example.org
```
