zecpaperwallet¶

zecpaperwallet is a Zcash Sapling paper wallet generator that can run completely offline. You can run it on an air-gapped computer to generate your shielded z-addresses, which will allow you to keep your keys completely offline.

Generated PDF Example: Paper Wallet

Download¶

zecpaperwallet is available as pre-built binaries from our release page. Download the zip file for your platform, extract it and run the ./zecpaperwallet binary.

Generating wallets¶

To generate a Zcash paper wallet, simply run ./zecpaperwallet

You’ll be asked to type some random characters that will add entropy to the random number generator. Run with --help to see all options

Saving as PDFs¶

To generate a Zcash paper wallet and save it as a PDF, run ./zecpaperwallet -z 3 --format pdf zecpaper-output.pdf

This will generate 3 shielded z-addresses and their corresponding private keys, and save them in a PDF file called zecpaper-output.pdf

Vanity Addresses¶

You can generate a “vanity address” (that is, an address starting with a given prefix) by specifying a --vanity argument with the prefix you want.

Note that generating vanity addresses with a prefix longer than 4-5 characters is computationally expensive. You can run it on multiple CPUs on your computer by specifying the --threads option.

./zecpaperwallet --vanity "zrocks" --threads 24

Compiling from Source¶

zecpaperwallet is built with rust. To compile from source, you install Rust. Basically, you need to:

curl https://sh.rustup.rs -sSf | sh

Checkout the zecpaperwallet repository and build the CLI

git clone https://github.com/adityapk00/zecpaperwallet.git
cd zecpaperwallet/cli
cargo build --release

The binary is available in the target/release folder.

Ensuring Security¶

When generating paper wallets that will store large amounts of crypto, please take special care to ensure the keys are generated and kept completely offline. 1. zecpaperwallet supports ARMv8 (Raspberry Pi 3+). You can put one in a Faraday cage along with a printer, and print out the PDFs securely. 2. Please ensure you supply random entropy when you run zecpaperwallet. Your entropy is mixed in with system-provided entropy to generate keys 3. If you can, run with unshare, which will disable all network interfaces to a process, providing you with an additional layer of safety. (See next section) 4. After you’ve generated the keys, you can tear off the Address potion of the wallet and take it to your online computer/phone to send the address funds. Please always keep the private key offline. 5. When you’re ready to spend the cold storage keys, import the private key into a full node, then don’t re-use the key again.

Run without network¶

If you are running a newish version of Linux, you can be doubly sure that the process is not contacting the network by running zecpaperwallet without the network namespace.

sudo unshare -n ./target/release/zecpaperwallet

unshare -n runs the process without a network interface which means you can be sure that your data is not being sent across the network.

Help options¶

USAGE:
    zecpaperwallet [FLAGS] [OPTIONS] [output]

FLAGS:
    -h, --help       Prints help information
    -n, --nohd       Don't reuse HD keys. Normally, zecpaperwallet will use the same HD key to derive multiple
                     addresses. This flag will use a new seed for each address
        --testnet    Generate Testnet addresses
    -V, --version    Prints version information

OPTIONS:
    -e, --entropy <entropy>       Provide additional entropy to the random number generator. Any random string,
                                  containing 32-64 characters
    -f, --format <FORMAT>         What format to generate the output in [default: json]  [possible values: pdf, json]
    -t, --taddrs <t_addresses>    Numbe rof T addresses to generate [default: 0]
        --threads <threads>       Number of threads to use for the vanity address generator. Set this to the number of
                                  CPUs you have [default: 1]
        --vanity <vanity>         Generate a vanity address with the given prefix
    -z, --zaddrs <z_addresses>    Number of Z addresses (Sapling) to generate [default: 1]

ARGS:
    <output>    Name of output file.