The Mcrypt option.

This plugin creates an (mcrypt) package.  It is built in the GNU
standard way (below).  It expects the mcrypt library header file to be
available, but often headers are not installed with the library.  On
Ubuntu the libmcrypt-dev package must be installed before running the
configure script.

The GNU standard way:

    ./configure ...
    make all
    make check
    make install

The last command will attempt to create a subdirectory in the first
directory on Scheme's library path.  If that directory is not writable
by you, super-user privileges may be required.

You can put a writable directory at the front of your Scheme's library
path by setting the MITSCHEME_LIBRARY_PATH environment variable and
creating a short optiondb file.

    mkdir ~/.mit-scheme-x86-64
    echo "(further-load-options #t)" > ~/.mit-scheme-x86-64/optiondb.scm
    export MITSCHEME_LIBRARY_PATH=\
	~/.mit-scheme-x86-64:/usr/local/lib/mit-scheme-x86-64
    make install

To use:

    (load-option 'mcrypt)
    (import-mcrypt)

Import-mcrypt will modify the REPL's current environment by adding
bindings linked to the plugin's exports.  They are not exported to the
global environment because they would conflict with the deprecated
exports from (runtime crypto).

To import into a CREF package set, add this to your .pkg file:

    (global-definitions mcrypt/)

    (define-package (your package name)
      (parent (your package parent))
      (import (mcrypt)
              mcrypt-encrypt-port
              ...))
