In this technique, it is possible to divide the key into two parts, public keys and private keys. Public keys are public =). You can share it with anyone you want, but the private one must be kept secret. Incoming messages would have been encrypted with the recipient’s public key, and can only be decrypted with corresponding private key. The keys are related mathematically, but cannot be derived each other practically.

As you can see in the figure, Bob wants to send a message to Alice. Bob encrypts the data (Hello Alice) using Alice’s public key and sends it. When the encrypted data receives Alice, she has to use her private keys in order to decrypt it.

After a short brief, lets come back to our topic. First you have to install the gnupg programme according to install procedure of your operating system or distro.

In order to communicate in an encrypted way, you have to generate your keys.

To generate the keys, open a terminal and type "gpg – -gen – -key". In order to export your public key out, type "gpg – - export [UID]"  or you may need to other people’s public keys. In that situation, save the public key in a file name is for example "Bob.txt" or "Bob.asc", then type in terminal "gpg – -import Bob.txt".

Now we have our public and private keys and also Bob’s public key has already imported. Assume that we have data.pdf as a document which we want to send in encrypted way. The only thing that we should do is, "gpg -u [sender] -r [Bob] –armor –encrypt [filepath]". If we want to decrypted the file that is sent by one of our friends, assume that that files is "abc.doc", the we should type "gpg – - output [filename] – -decrypt [encryptedfilepath]".

 After these information, i want to give you some extras;

gpg –list –keys list of all keys imported your system

gpg –list –sigs list of all signs imported your system

gpg –fingerprint list fingerprints as HEX

gpg –list-secret-keys shows imported secret keys

gpg –delete-key [UID] deletes any key according to User ID