Encrypting/decrypting files and folders ...

... in a desktop enviroment

To encrypt data:

1. Open Konqueror
2. Select the file or folder you wish to encrypt
3. From the context menu choose "Actions>Encrypt File" or "Actions>Archive and Encrypt Folder"
   
4. In the dialog window make all options visible and choose "Symmetrical Encryption"
   
5. Enter a password twice
6. A new file with the suffix "asc" (when encrypting a file) or "zip.gpg" (when encrypting a folder) will be created. This contains your encrypted data
   

NB! The original file/folder will still be available, so delete it if necessary.

To decrypt data:

In Konqueror simply choose "Open with Kgpg" from the context menu and enter the password.

... on a command line

To encrypt data with a passphrase:

gpg-zip -c -o filename.gpg data

where filename.gpg is the name of the encrypted file and data is the file or directory you wish to encrypt.

To decrypt data:

gpg-zip -d filename.gpg

You will be prompted for the passphrase you provided during encryption.

Encrypting with keys

Consult Kgpg or gpg manual to learn how to use private/public keys to encrypt your data.