This is GNU Libtasn1, a small ASN.1 library.

The C library (libtasn1.*) is licensed under the GNU Lesser General
Public License version 2.1 or later.  See the file COPYING.LIB.

The command line tool, self tests, examples, and other auxilliary
files, are licensed under the GNU General Public License version 3.0
or later.  See the file COPYING.

The manual is in doc/.  You can also browse the manual and see updates
about the project on the homepage:

http://www.gnu.org/software/libtasn1/