bx bitcoin256

Perform a SHA256 hash of a SHA256 hash of Base16 data and then reverse the byte order.

$ bx bitcoin256 --help

Usage: bx bitcoin256 [-h] [--config VALUE] [BASE16]                      

Info: Perform a SHA256 hash of a SHA256 hash of Base16 data and then     
reverse the byte order.                                                  

Options (named):

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

Arguments (positional):

BASE16               The Base16 data to hash. If not specified the data  
                     is read from STDIN.

Example 1

$ bx bitcoin256 900df00d

23429b4cc436b2ebd4aa33b904a1e08f195715c34d275e9088ea7b12af3872cd

Example 2

piped commands, bitcoin256 equivalent (with byte order reversed)

$ bx sha256 900df00d | bx sha256

f0ebe3bd55115e573ba35c2b1b65a923ff64c7a548d0deab73f9314754a9149d
cd7238af127bea88905e274dc31557198fe0a104b933aad4ebb236c44c9b4223

Notice that the resulting hash [cd7238af...] is in the reverse byte order of the bitcoin256 command output [...af3872cd]. This is an idiosyncrasy of the reference implementation.