bx stealth shared

Derive the secret shared between an ephemeral key pair and a scan key pair.

$ bx stealth-shared --help

Usage: bx stealth-shared [-h] [--config value] SECRET [PUBKEY]

Info: Derive the secret shared between an ephemeral key pair and a scan
key pair. Provide scan SECRET and ephemeral PUBKEY, or ephemeral SECRET
and scan PUBKEY.

Options (named):

-c [--config]        The path to the configuration settings file.
-h [--help]          Get a description and instructions for this command.

Arguments (positional):

SECRET               A Base16 EC private key. Either the scan or
                     ephemeral secret.
PUBKEY               A Base16 EC public key. Either the scan or ephemeral
                     public key. If not specified the key is read from
                     STDIN. 

Through the public exchange of public keys two parties can obtain a shared secret. The secret is unlocked by each only through possession of the private key corresponding to the exchanged public key.

In stealth terminology the scan secret is created by the receiver and the ephemeral secret is created by the spender. The scan secret can be safely reused and the ephemeral secret should be unique for each payment. Each secret is a private key and has a derivable public key.

Example 1

scan secret, ephemeral public key

$ bx stealth-shared af4afaeb40810e5f8abdbb177c31a2d310913f91cf556f5350bca10cbfe8b9ec 0247140d2811498679fe9a0467a75ac7aa581476c102d27377bc0232635af8ad36

78dac4cad97b62efc67aff4890c3bc799815d144c5f93b171f559b43bca52590

Example 2

ephemeral secret, scan public key

$ bx stealth-shared 8ed1d17dabce1fccbbe5e9bf008b318334e5bcc78eb9e7c1ea850b7eb0ddb9c8 031bab84e687e36514eeaf5a017c30d32c1f59dd4ea6629da7970ca374513dd006

78dac4cad97b62efc67aff4890c3bc799815d144c5f93b171f559b43bca52590

Notice the resulting shared secret is the same as in the previous example.