GnuPG

Some of basic informations, from http://www.gnupg.org/ site:

GnuPG is the GNU project‘s complete and free implementation of the OpenPGP standard as defined by
RFC4880. GnuPG allows to encrypt and sign your data and communication, features a versatile key managment system as well as access modules for all kind of public key directories. GnuPG, also known asGPG, is a command line tool with features for easy integration with other applications. A wealth of frontend applications and
libraries are available. Version 2 of GnuPG also provides support for S/MIME.

GnuPG is Free Software (meaning that it respects your freedom). It can be freely used, modified and distributed under the terms of the GNU General Public License.

GnuPG comes in two flavours:
1.4.10 is the well known and portable standalone version, whereas
2.0.15 is the enhanced and somewhat harder to build version.

Project Gpg4win provides a Windows version of GnuPG. It is nicely integrated into an installer and features several frontends as well as (German) manuals.

Project Aegypten developed the S/MIME functionality in GnuPG 2.

more information on http://www.gnupg.org/ site

GnuPG installation:

Newest version you can always download form http://www.gnupg.org site

Installation on Unix (from sources) should not be a problem, especially that those who do that way usually reads documentation before installation, I compiled that way (Solaris 2.6, gcc v.3.2.1):
./configure --prefix=/usr/local/gnupg-VER \
--mandir=/usr/local/man --infodir=/usr/local/info \
--with-ldap --with-gnu-ld
make

make check
later /bin/su and make install
This will install GnuPG in directory
/usr/local/gnupg-VER, after that I make a symbolic link:
ln -s /usr/local/gnupg-VER /usr/local/gnupg

and I add proper paths to PATH or I make a symbolic links:
ln -s /usr/local/gnupg/bin/gpg* /usr/local/bin/
Maybe this looks weird, but I can assure that this is premeditated action, which simplyfies me updates of software.
OK. This should work, you can check GnuPG version:
gpg --version
gpg (GnuPG) 1.2.2
Copyright (C) 2003 Free Software Foundation, Inc.
This program comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to redistribute it
under certain conditions. See the file COPYING for details.

Home: ~/.gnupg
Algoritms:
Pubkey: RSA, RSA-E, RSA-S, ELG-E, DSA, ELG
Cipher: 3DES, CAST5, BLOWFISH, AES, AES192, AES256,
TWOFISH
Hash: MD5, SHA1, RIPEMD160, SHA256
Compression: Uncompressed, ZIP, ZLIB

When you find this warning in first line:
Warning: using insecure memory!
You can do two things:
chmod u+s /usr/local/gnupg/bin/gpg
or put following line in config of gpg:
‘no-secmem-warning’
echo "no-secmem-warning" >>
~/.gnupg/gpg.conf
I choose this second option.

Installation under Windows – you need to simply download and unpack binaries in directory (default C:\GnuPG).
Now you need to add entries to registry, (you can use file gnupg-w32.reg).
If you change default installation directory, then you need to modify pathes in registry of course.
I will not write about key generation and ideology, because there is many pages about it, you can find it by yourself 🙂