To say it straight in only one sentence: gpg4usb is a very easy to use portable-application, which combines a simple text-editor with a GnuPG-frontend to write, encrypt and decrypt your text-messages and files. gpg4usb should work on almost any computer you’re working on, should it be a Linux-machine or even one with a Microsoft-OS running.
Almost the only thing required is an available usb-port you are allowed to access. With this application you can write safe and encrypted messages anywhere you are: should it be an internet-cafe, at work or somewhere else on holiday… and you always have the encryption-keys available for usage!
The usage of gpg4usb should be highly self-describing, since the user-interface and all the options it offers are clear cut: Simply execute the binary on your usb-pendrive and start typing e.g. the Mailtext you want to be encrypted. If you’re done, choose the right gpg/pgp-key for the person you are writing to and hit the encrypt-icon at the top of the application-window. The resulting encrypted text you can save as a text-file to send it as mail-attachment, or copy it directly into your mail-user-agent or webmail-website. To make sure, you can read this message by yourself afterwards, encrypt it for the recipient and to yourself at the same time – if you want, you can mark as much keys as you want to encrypt for.
You want to add a gpg/pgp-key to your mobile keyring? Nothing’s easier than that: just hit the crypto-menue-entry and choose Import Key from File or Import Key from Editor. This means that it’s possible to import an ascii-armored pubkey via file-dialog, or via copy&paste into your editor-window. If you find a key e.g. on a website, just copy it, paste it into the gpg4usb-editor and hit Import Key from Editor – that’s it, and the key shows up on your keyring!
Pasted from <http://gpg4usb.cpunk.de/about.html>
Download
You can get our latest Release v0.3.2 by clicking the download link below. Since v0.2.4 the included executables are upx-compressed by default.
| Filename | Size* | sha1 |
| gpg4usb-0.3.2-1.zip | 14.8MB / 18.6MB | efeeaeff2883ded6abfe6378113c219e5e897bb0 |
* Size zipped / unzipped
Just download the zip-File and unzip it onto your usb-pendrive. Then simply change into the folder gpg4usb at your usb-drive, and execute the binary in there:
start_linux or start_windows.exe – should be easy to determine, which one’s yours 
Since gpg4usb is free software, licensed under the GNU General Public License (GPL), you can use it on as many machines as you want. Copy it, modify and redistribute it, give gpg4usb to as many people as possible!
Pasted from <http://gpg4usb.cpunk.de/download.html>