bitcoin-encrypted-backup

Command-line tool & Rust crate that lets you encrypt descriptors (or arbitrary data) with a set of public keys (or xpubs) and later decrypt when at least one of them is physically present—either via a local file containing the key or automatically fetched from a signing device. Devices are not mandatory; you can use the tool completely off-device.

CLI

Build

To build the cli without device support:

cargo build --bin beb --release --no-default-features --features="cli"

or with devices support:

cargo build --bin beb --release --no-default-features --features="cli,devices"

Note: if a signing device supported by async-hwi is connected and unlocked, the CLI will automatically try to fetch a set of xpubs from it.

Usage:

$ beb --help
Usage: beb <COMMAND>

Commands:
  encrypt  Encrypt some descriptor
  decrypt  Decrypt an encrypted descriptor with a given xpub
  help     Print this message or the help of the given subcommand(s)

Options:
  -h, --help     Print help
  -V, --version  Print version

$ beb encrypt --help
Encrypt some descriptor

Usage: beb encrypt [OPTIONS]

Options:
  -f, --file <FILE>      Input file containing the descriptor
  -o, --output <OUTPUT>  Optional output to encrypted descriptor
  -h, --help             Print help

$ beb decrypt --help
Decrypt an encrypted descriptor with a given xpub

Usage: beb decrypt [OPTIONS]

Options:
  -f, --file <FILE>      Input file to be decrypted
  -k, --key <KEY>        The key containing a xpub
  -o, --output <OUTPUT>  Optional decrypted descriptor
  -h, --help             Print help

Library usage

Encryption

let descriptor = Descriptor::<DescriptorPublicKey>::from_str("<descriptor
string>").unwrap();
let backp = EncryptedBackup::new().set_payload(&descriptor).unwrap();
let encrypted_blob = backp.encrypt().unwrap();

Decryption

let encrypted_blob: Vec<u8> = vec![/* your encrypted descriptor*/];
let key = DescriptorPublicKey::from_str("<your xpub>").unwrap();
let descriptor = EncryptedBackup::new()
    .set_encrypted_payload(&encrypted_blob)
    .unwrap()
    .set_keys(vec![key])
    .decrypt()
    .unwrap();

WASM support

This carate can be build against these wasm targets:

• wasm32-unknown-unknown
• wasm32-wasip1

Note: rand feature must be disabled for these target:

cargo build --target wasm32-unknown-unknown --no-default-features --features "miniscript_latest"

Features

Note: the devices feature uses async-hwi crate, see there for supported signing devices.