[lightwalletd](https://github.com/zcash/lightwalletd) is a backend service that provides a bandwidth-efficient interface to the Zcash blockchain. Currently, lightwalletd supports the Sapling protocol version and beyond as its primary concern. The intended purpose of lightwalletd is to support the development and operation of mobile-friendly shielded light wallets.
lightwalletd is a backend service that provides a bandwidth-efficient interface to the Zcash blockchain for mobile and other wallets, such as [Zecwallet](https://github.com/adityapk00/zecwallet-lite-lib).
Lightwalletd has not yet undergone audits or been subject to rigorous testing. It lacks some affordances necessary for production-level reliability. We do not recommend using it to handle customer funds at this time (April 2020).
Documentation for lightwalletd clients (the gRPC interface) is in `docs/rtd/index.html`. The current version of this file corresponds to the two `.proto` files; if you change these files, please regenerate the documentation by running `make doc`, which requires docker to be installed.
The `zcashd` can be configured to run `mainnet` or `testnet` (or `regtest`). If you stop `zcashd` and restart it on a different network (switch from `testnet` to `mainnet`, for example), you must also stop and restart lightwalletd.
It's necessary to run `zcashd --reindex` one time for these options to take effect. This typically takes several hours, and requires more space in the `.zcash` data directory.
Lightwalletd uses the following `zcashd` RPCs:
-`getblockchaininfo`
-`getblock`
-`getrawtransaction`
-`getaddresstxids`
-`sendrawtransaction`
## Lightwalletd
First, install [Go](https://golang.org/dl/#stable) version 1.11 or later. You can see your current version by running `go version`.
You will need to supply an x509 certificate that connecting clients will have good reason to trust (hint: do not use a self-signed one, our SDK will reject those unless you distribute them to the client out-of-band). We suggest that you be sure to buy a reputable one from a supplier that uses a modern hashing algorithm (NOT md5 or sha1) and that uses Certificate Transparency (OID 1.3.6.1.4.1.11129.2.4.2 will be present in the certificate).
To check a given certificate's (cert.pem) hashing algorithm: