I think the RSA algorithm is fascinating, just because of the impact it has had on the industry. Imagine a world without public-key encryption. Crazy right? <i>(Obviously there would be other ways to achieve public-key encryption if RSA had never come along... but you get my point)</i>.<p>While we&#x27;re on the subject: This book is a great read: <a href="http:&#x2F;&#x2F;www.amazon.com&#x2F;Nine-Algorithms-That-Changed-Future&#x2F;dp&#x2F;0691158193" rel="nofollow">http:&#x2F;&#x2F;www.amazon.com&#x2F;Nine-Algorithms-That-Changed-Future&#x2F;dp...</a>