lightwalletd is under active development, some features are more stable than others. The code has not been subjected to a thorough review by an external auditor, and recent code changes have not yet received security review from Electric Coin Company's security team.
Developers should familiarize themselves with the wallet app threat model, since it contains important information about the security and privacy limitations of light wallets that use lightwalletd.
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.
To view status of CI pipeline
To view detailed Codecov report
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.
Local/Developer docker-compose Usage
You must start a local instance of
zcashd, and its
.zcash/zcash.conf file must include the following entries
(set the user and password strings accordingly):
txindex=1 lightwalletd=1 experimentalfeatures=1 rpcuser=xxxxx rpcpassword=xxxxx
zcashd can be configured to run
regtest). If you stop
zcashd and restart it on a different network (switch from
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
First, install Go version 1.17 or later. You can see your current version by running
Clone the current repository into a local directory that is not within any component of
$HOME/go by default), then build the lightwalletd server binary by running
To run SERVER
Assuming you used
make to build the server, here's a typical developer invocation:
./lightwalletd --no-tls-very-insecure --zcash-conf-path ~/.zcash/zcash.conf --data-dir . --log-file /dev/stdout
./lightwalletd help to see the full list of options and arguments.
Run a local instance of
zcashd (see above), except do not specify
Ensure Go version 1.17 or later is installed.
x509 Certificates 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 18.104.22.168.4.1.1122.214.171.124 will be present in the certificate).
To check a given certificate's (cert.pem) hashing algorithm:
openssl x509 -text -in certificate.crt | grep "Signature Algorithm"
To check if a given certificate (cert.pem) contains a Certificate Transparency OID:
echo "126.96.36.199.4.1.11188.8.131.52 certTransparency Certificate Transparency" > oid.txt openssl asn1parse -in cert.pem -oid ./oid.txt | grep 'Certificate Transparency'
To use Let's Encrypt to generate a free certificate for your frontend, one method is to:
- Install certbot
- Open port 80 to your host
- Point some forward dns to that host (some.forward.dns.com)
certbot certonly --standalone --preferred-challenges http -d some.forward.dns.com
- Pass the resulting certificate and key to frontend using the -tls-cert and -tls-key options.
To run production SERVER
Example using server binary built from Makefile:
./lightwalletd --tls-cert cert.pem --tls-key key.pem --zcash-conf-path /home/zcash/.zcash/zcash.conf --log-file /logs/server.log
lightwalletd caches all blocks from Sapling activation up to the most recent block, which takes about an hour the first time you run lightwalletd. During this syncing, lightwalletd is fully available, but block fetches are slower until the download completes.
After syncing, lightwalletd will start almost immediately,
because the blocks are cached in local files (by default, within
/var/lib/lightwalletd/db; you can specify a different location using
--data-dir command-line option).
lightwalletd checks the consistency of these files at startup and during
operation as these files may be damaged by, for example, an unclean shutdown.
If the server detects corruption, it will automatically re-downloading blocks
zcashd from that height, requiring up to an hour again (no manual
intervention is required). But this should occur rarely.
If lightwalletd detects corruption in these cache files, it will log
a message containing the string
CORRUPTION and also indicate the
nature of the corruption.
Darksidewalletd & Testing
lightwalletd now supports a mode that enables integration testing of itself and wallets that connect to it. See the darksidewalletd docs for more information.
We welcome pull requests! We like to keep our Go code neatly formatted in a standard way,
which the standard tool gofmt can do. Please consider
adding the following to the file
.git/hooks/pre-commit in your clone:
#!/bin/sh modified_go_files=$(git diff --cached --name-only -- '*.go') if test "$modified_go_files" then need_formatting=$(gofmt -l $modified_go_files) if test "$need_formatting" then echo files need formatting (then don't forget to git add): echo gofmt -w $need_formatting exit 1 fi fi
You'll also need to make this file executable:
$ chmod +x .git/hooks/pre-commit
Doing this will prevent commits that break the standard formatting. Simply run the
gofmt command as indicated and rerun the
git add and
git commit commands.