In Code: A Mathematical Journey Hardcover – September 1, 2001

This book is amazing. It offers a highly readable introduction to the mathematical life. The best way to teach someone to love a subject like math is to be proficient in it yourself and have fun with it. This book introduces a wealth of mathematical puzzles to solve and chronicles a young person's journey to solving real world problems. It has a lot of information on cryptography and is a generally interesting read even if you don't want to take the time to understand all the math. I haven't finished the book, but I have enjoyed what I have read. Highly recommended reading for anyone interested in mathematics and cryptography or anyone who likes a good biography.

Number theory is the branch of mathematics that deals with counting numbers, 1, 2, 3... Sarah Flannery, born in 1982, entered that world because her father was a mathematician. What happened to Sarah is that she entered the number theory and cryptology world at age 16 with a science project that was new and original, and was a challenge to the way prime numbers were being used in the most popular of encryption systems. She has written _In Code: A Mathematical Journey_ (Workman Publishing) about how this happened, and its aftermath (or After Math, as a final section of the book is called). It is a delight. It is a book of mathematics, it is true, but it is also an inspiring look at a girl who had an exemplary upbringing and a strong streak of intellectual curiosity.
Central to Sarah's story is the blackboard in the dining room of her home. She grew up in the shadow of Blarney Castle, she and her four brothers raised by an independent-thinking pair of parents. At meals, the blackboard would be the focal point for discussion of puzzles. She gives plenty of these for the reader to work on. Some are familiar, like, "Given a five-liter jar and a three-liter jar and an unlimited supply of water, how do you measure out four liters exactly?" Some got into more difficult concepts: "How might you determine the average earnings of a group of people in a room (at a class reunion, perhaps) without any individual's divulging his or her salary?" This second puzzle gives a clue into getting information and hiding information, a theme throughout the book. (All the puzzles are left for the reader to work on, and such work will repay effort in understanding the book, but answers are given.)
Sarah repeatedly and sweetly apologizes for digging deep into number theory; before explaining matrices, she writes, "I promise that from then on there will be no more explicit mathematics, only light explanations of mathematical ideas." The main mathematical parts of the book are restricted to two chapters which she invites those who just can't stand the math to skim, and then there are appendices available for those who want to learn more. Sarah's project explained how the most famous current encoding system works, but before she was done, she had invented one of her own. She explains both systems and a lot of number theory along the way. She tells about her interactions with the judges for the competition, and the pressures that eventually resulted in her winning a silver trophy, a cash prize, fame, travel, and interactions with the media. Her lively descriptions of what happened after the newspapers got hold of the story of the genius girl are among the most amusing parts of the book; she and her family turned down a contract with Pepsi, but she did help in an article about herself which appeared in the Spice Girls pop magazine.
Here is a book full of mathematical ideas that are worth knowing about, and a bright, funny, modest young woman to lead us through them; Sarah denies that she is a genius, saying that she has met geniuses and that she does not have the spark that distinguishes genius from mere intelligence. Maybe so, but she is a likable author, and it is a delight to hear her describe with affection her parents who obviously know what they are doing. But perhaps the most inspiring part of the book is how well the mathematical community came together to nurture this newcomer. Time and again, experts who worked in the cryptology field were eager to help out. When it seemed that her new code system was patentable and might even make her a millionaire, Sarah got advice even from the mathematicians who might have shared in the bounty that, as one wrote her, "Mathematics should be above such mercenary nonsense!" Mathematical ideas should be freely shared by all, she agreed. It turns out that her system eventually proved vulnerable to attack, thus not quite as secure as the first system, but it doesn't matter. Sarah's book can easily be enjoyed by those who don't like math at all, and would be especially good reading for young people. It is full of happy discoveries in math, and discoveries about people, and it is wonderfully optimistic.

I teach Cryptology at the University level. I had read this book many moons ago, but had lost my copy. Last spring I had a stellar student in a class, a young woman who is gifted in the field of Mathematics. While searching for a new text on Cryptology, I stumbled upon this book and the young woman's name immediately popped into my head. I bought the book for her.

Sarah Flannery's story is one of encouragement. My hope is that my former student, now a graduate, will draw strength from Sarah's book.

I highly recommend this book.

This is the second book I've read on my own, self study of cryptography. But I remember from the book, "Secrets and Lies" by Bruce Schneier that new cryptography systems occur often. It is not possible to foresee all attacks that would break the security. That said, even though Ms. Flannery's encryption method had a vulnerability it still is interesting enough to learn from. That is why I wish she would have described the thinking process behind the math of her main algorithm. Sure the appendix has all the math (Which I still need to go through.), but if she would have described the encryption algorithm as she did her journey learning cryptography, the book would be phenomenal.

Again, the book is great and I give it 5 stars. She explains complex math in a way that is both interesting and understandable. And even though I wanted more explanation about the main algorithm, at least all the math (including Mathematica code) is in the appendix. I guess this was done because the book's main focus is supposed to be the story. But don't let that deter you, this is a math book too. And while it is fundamental math topics, the math is not watered down. It is presented in a way in which you can understand and learn from it.

I highly recommend this book. It shows with some hard work and a basic math understanding, you can still contribute and discover things. I have been working with logarithmic spirals trying to find a use for them in cryptography. I had worked at it hard and realized after all the work I still don't have a proven solution. But reading this book by Ms. Flannery, you see that it is more about the journey.

irish teenager Sarah Flannery decided to do a science fair project on codes. To do so, she taught herself computer programming and number theory, building on the many mathematical puzzles and brainteasers her mathematician father had set her over the years. One science fair and one summer internship later, she designed a new twist on a famous private/public key algorithm. Despite a weakness in her code that she announced to the world as soon as she found it, Flannery went on to win the Intel International Science Fair.

This book has two main strengths: Sarah's bright, modest, honest, innocent voice; and a lovely presentation (written with her father's help) of modular arithmetic. A delight to read.