Author: Nikos Mavroyanopoulos <[email protected]>.

The author says in the README file:
Look at COPYING for license information and the individual files for more
information. COPYING applies only for the mcrypt program and not the
algorithms which most of them are public domain.

And the attached COPYING.LIB is the GNU Library General Public License, so
this software is released under the terms of the GNU Library General Public
License.

In the headers of the source files he says:
/*
* Copyright (C) 1998,1999,2001 Nikos Mavroyanopoulos
*
* This library is free software; you can redistribute it and/or modify it under the terms of the
* GNU Library General Public License as published by the Free Software
* Foundation; either version 2 of the License, or (at your option) any
* later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*/

On Debian systems, the complete text of the GNU Library General Public License
can be found in /usr/share/common-licenses/LGPL-2.

Debian packaging:
It was put together by Raphael Bossek <[email protected]>
from the following sources:

ftp://mcrypt.hellug.gr/pub/mcrypt/libmcrypt

Changes:
* Added Debian GNU/Linux packaging files.

The actual project page for the upstream is http://mcrypt.sourceforge.net/.
The actual maintainer of the package is RISKO Gergely <[email protected]>.