passphrase
==========

Securely computes a key from a passphrase and salt.

-b --output-bytes=N  Number of bytes to output. The default is 32,
                     the number of bytes in a Bitcoin private key.
-s --salt-file=FILE  The file to save salt info in. The default is
                     ./salt. An empty string or '/dev/null' will
                     disable writing a salt file.
-e --echo            Echo the passphrase.
--help               Show this help.

Requires passlib.