GNUPg

1) To create a key
gpg ----gen-key

2) To generate export key used for distribution eg on the home page, use the command

gpg --export -ao ullas

-a will produce ascii output and -o will create an output file: here its named ullas

3) To import a key to the keyring

gpg --import redhat2.asc

This will import the redhat key into keyring. Next we have to sign this key. This will add trust. So do as follows.

gpg --sign-key RedHat

4) To check signature of an encrypted data

gpg --verify data

5) Now suppose you want to send a file message.txt to user RedHat

gpg -sear RedHat message.txt

-s Sign, -e Encrypt, -a Ascii, -r to encrypt user id

6) Now RedHat can decrypt as follows

gpg -o message -d message.asc

7) Windows has email client that support gnupg. Its thunderbird with Enigmail plugin support (http://web.archive.org/web/20050415033810/http://ullas.modblog.com/?gourl=http://enigmail.mozdev.org/download.html).