-: Pretty Good Privacy, also know as PGP,
is an encryption program that's used for signing,
encrypting, and decrypting emails.
Over the years, PGP's use has expanded beyond emails,
though, and includes an entire suite of protocols
that can encrypt emails, files, and even entire hard disks.
PGP uses an older algorithm, though, known as IDEA,
which you may remember from our symmetric algorithm lesson.
Now you may be wondering, why didn't I just cover PGP
all the way back in the symmetric algorithm lesson then?
Well, PGP is actually a hybrid cryptographic tool
because it uses a symmetric cipher
for the bulk data encryption, but it uses RSA,
an asymmetric cipher, to create the digital signatures used
in signing its emails and to send the session keys
over an un-trusted network.
This is what I meant before when I said
that we often combine both symmetric and asymmetric ciphers
to give us a hybrid approach or implementation.
Now PGP uses key sizes of 128 bits
or more for symmetric functions and key sizes
between 512 bits and 2,048 bits for its asymmetric function.
Over time, PGP became an open source encryption cipher,
and as such, it was able to be forked and used
for further development.
The result of that was GPG.
This stands for the GNU Privacy Guard,
and it's an implementation of cryptography
that's used to provide you with confidentiality in your data
by encrypting it like PGP did.
Now, GPG is actually a newer version of PGP,
or the Pretty Good Privacy encryption suite.
The newer GPG uses the more modern AES encryption algorithm
instead of that weaker IDEA symmetric algorithm.
Now GPG is a freely available
and non-patented encryption solution that's available
for Linux, Windows, and Macintosh operating systems.
So if you're looking for one to try out,
you can download GPG and get started today.