Pretty Good Privacy (PGP) - "Cryptography"

Pretty Good Privacy or PGP is one such cryptography system that uses the public-private key pair to encrypt & decrypt data securely.

Encryption:-
In first step, PGP compresses the plaintext data that has to be encrypted using a predefined compression algorithm.
Next, PGP creates a random single-use encryption key known as the session key. Which is randomly generated & is used to encrypt the plaintext data into ciphertext data.
Finally, the session key generated in step 2 is encrypted using the recipient’s public key. Once this is done, PGP then sends this encrypted session key & the ciphertext data to the recipient.

Decryption:-
First of all, PGP at the receiver’s end uses the private key of the recipient to retrieve the encrypted session key.
This retrieved session key is then used to decrypt the encrypted ciphertext data sent by the source.
Finally, this retrieved compressed plaintext data is uncompressed & the original plaintext data is obtained.

Popular PGP Tools:-

1) PGP Freeware v6.5.8
The official PGP implementation.
http://web.mit.edu/network/pgp.html

2) PGP Mail
Allows users to send & receive PGP encrypted e-mails.
http://web.mit.edu/network/pgp.html

3) PGP Disk
Allows users to encrypt a few files on the local disk or even the entire hard disk.
http://www.pgpi.org/products/pgpdisk/

4) PGP Fire
A firewall that comes with the PGP software.
http://www.networkingfiles.com/Firewalls/downloads/pgpfiredownload.htm

5) PGP Fone
A tool that allows users to make secure telephone calls using a modem or over the internet.
http://www.pgpi.org/products/pgpfone