Let's take a look at two more encryption technologies that
are covered on the exam, but they're a little
less commonly used.
Elliptic curve cryptography and quantum cryptography.
All public key cryptography is based upon the difficulty of
solving complex mathematical problems.
In the case of the RSA algorithm, the security of the algorithm
depends upon the difficulty of factoring the product of two
large prime numbers.
You might recall from a math class that prime numbers are those that
are divisible only by themselves, and the number, one.
Common examples of prime numbers include 2,
3, 5, 7, and 11.
Now, if I told you that I was going to multiply two prime
numbers together and provide you with the answer,
you might think that you'd be able to perform that calculation.
For example, if I tell you that 15 is the product of two
prime numbers,
you can easily determine that those numbers are three and five.
Or if I asked you to perform the prime factorization of 21,
you'd quickly figure out that the two prime numbers are
three and seven.
RSA and other cryptographic algorithms that depend upon the
difficulty of factoring prime numbers use much larger
prime numbers,
however. What if I showed you this product and asked you to identify
the two prime numbers that went into it?
Now that's a little more difficult, isn't it?
Currently, there is no effective way to solve the prime
factorization problem efficiently for large numbers.
If someone discovered an efficient way to do this,
all of the cryptographic algorithms that depend upon prime
factorization would immediately become insecure.
Elliptic curve cryptography or ECC
does not depend upon the prime factorization problem.
It uses a completely different problem known as the
elliptic curve
discrete logarithm problem.
Now, explaining that problem is a lot more difficult than the prime
factorization problem, but fortunately, you won't need to
understand how ECC works on the exam.
Just remember that it uses a different approach than the prime
factorization problem.
Quantum computing is an emerging field that attempts to use quantum
mechanics to perform computing tasks.
It's still mostly a theoretical field,
but if it advances to the point where that theory becomes
practical to implement, quantum cryptography may be able
to defeat cryptographic algorithms that depend upon factoring
large prime numbers.
Unfortunately, the use of elliptic curve cryptography would not
provide protection against quantum attacks.
Elliptic curve approaches are even more susceptible to quantum attack
than prime factorization algorithms.
At the same time, quantum computing may be used to
develop even stronger cryptographic algorithms that
would be far more secure than modern approaches.
We'll have to wait and see how those develop to provide us with
strong quantum communications in a post-quantum era.