Secret values is a Common Lisp library designed to reduce the risk of
accidentally revealing secret values such as passwords.

Source code at

Applications will often have to deal with values that should be kept
secret, e.g. a password for accessing the applications database. There
will allways be a risk that such a secret value is accidentally
revealed e.g. in a backtrace or log file. Fixing this can be difficult
because the code that generates the backtrace or log is often not part
of the application. Turning off logging or backtrace is seldom an
option. Making sure that logs and backtrace are kept secure can also
be difficult.

This library provides a simple wrapper type that can be used to
conceal secret data. This wrapper tries to keep it's value secret by
overriding print-object and some other tricks. In order to get the
full benefits, the value should be concealed as early as possible and
revealed as late as possible. For example, a database library should
accept the password as a concealed value and only reveal it just
before it's used to authenticate with the database. This will greatly
reduce the risk of the password ending up in a log file or backtrace.

All symbols are exported from the package SECRET-VALUES.

The function CONCEAL-VALUE wraps a value into an object of type
SECRET-VALUE. An optional name can be provided. The name is intended
for debugging only and is included when the object is printed.

To get the value back, call REVEAL-VALUE.

The function ENSURE-VALUE-REVEALED behaves like REAVEAL-VALUE when
called with an argument of type SECRET-VALUE, otherwise it just
returns it's argument verbatim. This makes it easy to write code that
accepts both secret and plaintext values.