- [Instructor] There are many
different encryption algorithms
that you can choose from when trying to achieve
one of the four goals of cryptography.
Let's talk about some of the things you should watch for
when selecting an encryption algorithm.
It's important to remember
that encryption is very complicated.
It uses sophisticated, mathematical techniques
and even the smallest flaw
can render an algorithm insecure.
For this reason, you should never try
to build your own encryption algorithm
unless you really, really know what you're doing.
You wouldn't try to perform heart surgery on yourself,
so don't try to build your own encryption either.
Similarly, if a vendor claims that their software
is secured with a proprietary encryption algorithm
and they won't share the details,
view that claim with the skepticism it deserves.
It's a big red flag.
For the same reason, you should choose
an encryption algorithm that is proven.
The details on encryption algorithms
are normally published and open for inspection
by the security community.
This public vetting process is important
because it allows mathematicians and cryptographers
to review the details of the algorithm and ensure
that it is both well-designed and free of back doors
that might allow unattended access to information.
When you choose an encryption algorithm you may also be able
to select the length of your encryption key.
Not all algorithms allow this
as some have fixed length keys.
If you are able to choose your key length,
the longer the key the more secure your information will be.
There is a downside, however.
As keys get longer, the performance
of the algorithm goes down.
You're trading off security for speed and performance.
Choosing a long key is important
because it makes it much more difficult
for someone to guess the key that you've used.
Here's an example of what
a 40-bit encryption key looks like.
A bit is simply a one or a zero in binary
and a 40-bit key consists of forty ones and zeroes.
There are over one trillion possible combinations
for this key.
That may sound like a lot, but it's possible
for a computer to break this key.
If we bump the encryption up to a 128-bit key
here is what it looks like.
There are enough possibilities here
that it wouldn't be feasible to guess the key
with a modern computer.
And when we go to a 1024-bit key,
we get some really strong security.
When you choose your encryption approach,
you'll need to perform your own cost-benefit analysis
and select a key length that balances your security goals
with the speed of encryption and decryption.